@article{nafadi_lucier_yaman_gleich_rizkalla_2021, title={Long-term behavior of precast, prestressed concrete sandwich panels reinforced with carbon-fiber-reinforced polymer shear grid}, volume={66}, ISSN={["0887-9672"]}, DOI={10.15554/pcij66.5-01}, abstractNote={■ The applied fatigue testing did not affect the ultimate performance of the panels and had a minimal effect on the composite action between the wythes. Precast concrete sandwich panels are typically used to construct high-performance, energy-efficient building envelopes. These panels typically consist of two concrete wythes separated by rigid foam insulation, such as expanded polystyrene (EPS) or extruded polystyrene (XPS). The panels are designed to resist floor loads as well as wind or seismic lateral loads while providing efficient insulation to the structure. They are often fabricated with heights over 45 ft (13.7 m) and widths up to 15 ft (4.6 m). Wythe thickness commonly ranges from 2 to 6 in. (50.8 to 152.4 mm), and overall panel thickness may be from 6 to over 12 in. (304.8 mm). Longitudinal prestressing is normally provided in both concrete wythes to control cracks.}, number={5}, journal={PCI JOURNAL}, author={Nafadi, Mohamed K. and Lucier, Gregory and Yaman, Tugce Sevil and Gleich, Harry and Rizkalla, Sami}, year={2021}, pages={23–38} }
 @article{khalafalla_pour-ghaz_elsafty_rizkalla_2019, title={Durability of CFRP strands used for prestressing of concrete structural members}, volume={228}, ISSN={["1879-0526"]}, DOI={10.1016/j.conbuildmat.2019.116756}, abstractNote={This paper presents a comprehensive research conducted to study the synergistic effect of environmental conditions and sustained loading on the mechanical properties of Carbon Fiber Reinforced Polymer (CFRP) prestressing strands. The environmental conditions included exposure of CFRP strands to alkaline solution and sustained loading at an elevated temperature of 55 °C for 3000 and 7000 h. The sustained loading was equivalent to 65 percent of the guaranteed tensile strength of the strands. Mechanical testing performed on the strands included tensile, shear and bond strength as well as evaluation of the elastic modulus of the CFRP strands as affected by the environmental conditions and sustained loading. Durability of the constituent materials of the CFRP strands was also studied.}, journal={CONSTRUCTION AND BUILDING MATERIALS}, author={Khalafalla, Omar and Pour-Ghaz, Mohammad and ElSafty, Adel and Rizkalla, Sami}, year={2019}, month={Dec} }
 @article{kazem_zhang_rizkalla_seracino_kobayashi_2018, title={CFRP shear strengthening system for steel bridge girders}, volume={175}, ISSN={["1873-7323"]}, DOI={10.1016/j.engstruct.2018.08.038}, abstractNote={This paper presents an investigation undertaken to study the effectiveness of using small-diameter CFRP strands for shear strengthening of steel bridge girders. The study includes a comprehensive experimental program to study effects of the CFRP reinforcement ratio and orientation of the strands. An analytical model, calibrated by the experimental tests, was used to provide design recommendation. Results of the study showed that the proposed strengthening system is effective in increasing the shear capacity of steel bridge girders and there was no sign of CFRP debonding or rupture failure commonly observed by CFRP laminates up to approximately 80% of the steel yield stress.}, journal={ENGINEERING STRUCTURES}, author={Kazem, Hamid and Zhang, Ye and Rizkalla, Sami and Seracino, Rudolf and Kobayashi, Akira}, year={2018}, month={Nov}, pages={415–424} }
 @article{el-gelani_high_rizkalla_abdalla_2018, title={Effects of Basalt Fibres on Mechanical Properties of Concrete}, volume={149}, ISSN={2261-236X}, url={http://dx.doi.org/10.1051/matecconf/201814901028}, DOI={10.1051/MATECCONF/201714901028}, abstractNote={This paper presents the results of an experimental program carried out to investigate the effects of Basalt Fibre Reinforced Polymers (BFRP) on some fundamental mechanical properties of concrete. Basalt fibres are formed by heating crushed basalt rocks and funnelling the molten basalt through a spinneret to form basalt filaments. This type of fibres have not been widely used till recently. Two commercially available chopped basalt fibres products with different aspect ratios were investigated, which are dry basalt (GeoTech Fibre) and basalt pre-soaked in an epoxy resin (GeoTech Matrix) .The experimental work included compression tests on 96 cylinders made of multiple batches of concrete with varying amounts of basalt fibre additives of the two mentioned types, along with control batches containing no fibres. Furthermore, flexural tests on 24 prisms were carries out to measure the modulus of rupture, in addition to 30 prisms for average residual strength test. Results of the research indicated that use of basalt fibres has insignificant effects on compressive strength of plain concrete, where the increase in strength did not exceed about 5%. On the other hand, results suggest that the use of basalt fibres may increase the compressive strength of concrete containing fly as up top 40%. The rupture strength was increased also by 8% to 28% depending on mix and fibre types and contents. Finally, there was no clear correlation between the average residual strength and ratios of basalt fibres mixed with the different concrete batches.}, journal={MATEC Web of Conferences}, publisher={EDP Sciences}, author={El-Gelani, A. M. and High, C.M. and Rizkalla, S. H. and Abdalla, E. A.}, editor={Diouri, A. and Boukhari, A. and Ait Brahim, L. and Bahi, L. and Khachani, N. and Saadi, M. and Aride, J. and Nounah, A.Editors}, year={2018}, pages={01028} }
 @article{el-gelani_high_rizkalla_abdalla_2018, title={Effects of Basalt Fibres on Mechanical Properties of Concrete}, volume={149}, ISSN={2261-236X}, url={http://dx.doi.org/10.1051/MATECCONF/201814901028}, DOI={10.1051/MATECCONF/201814901028}, abstractNote={This paper presents the results of an experimental program carried out to investigate the effects of Basalt Fibre Reinforced Polymers (BFRP) on some fundamental mechanical properties of concrete. Basalt fibres are formed by heating crushed basalt rocks and funnelling the molten basalt through a spinneret to form basalt filaments. This type of fibres have not been widely used till recently. Two commercially available chopped basalt fibres products with different aspect ratios were investigated, which are dry basalt (GeoTech Fibre) and basalt pre-soaked in an epoxy resin (GeoTech Matrix) .The experimental work included compression tests on 96 cylinders made of multiple batches of concrete with varying amounts of basalt fibre additives of the two mentioned types, along with control batches containing no fibres. Furthermore, flexural tests on 24 prisms were carries out to measure the modulus of rupture, in addition to 30 prisms for average residual strength test. Results of the research indicated that use of basalt fibres has insignificant effects on compressive strength of plain concrete, where the increase in strength did not exceed about 5%. On the other hand, results suggest that the use of basalt fibres may increase the compressive strength of concrete containing fly as up top 40%. The rupture strength was increased also by 8% to 28% depending on mix and fibre types and contents. Finally, there was no clear correlation between the average residual strength and ratios of basalt fibres mixed with the different concrete batches.}, journal={MATEC Web of Conferences}, publisher={EDP Sciences}, author={El-Gelani, A. M. and High, C.M. and Rizkalla, S. H. and Abdalla, E. A.}, editor={Diouri, A. and Boukhari, A. and Ait Brahim, L. and Bahi, L. and Khachani, N. and Saadi, M. and Aride, J. and Nounah, A.Editors}, year={2018}, pages={01028} }
 @article{kazem_rizkalla_kobayashi_2018, title={Shear strengthening of steel plates using small-diameter CFRP strands}, volume={184}, ISSN={["1879-1085"]}, DOI={10.1016/j.compstruct.2017.09.094}, abstractNote={This paper presents the results of a comprehensive research program, including experimental and analytical studies, to examine the use of small-diameter CFRP strands for shear strengthening of steel structures and bridges. The experimental program examined the effectiveness of the proposed strengthening system to increase the shear capacity of steel plates subjected to pure shear stresses using a unique test set up. A nonlinear finite element analysis (FEA), calibrated the experimental results, was used to study parameters which were not included in the experiments. Research findings indicated that the proposed system is effective for shear strengthening of steel structures and eliminated the typical debonding failure commonly observed by CFRP laminates.}, journal={COMPOSITE STRUCTURES}, author={Kazem, Hamid and Rizkalla, Sami and Kobayashi, Akira}, year={2018}, month={Jan}, pages={78–91} }
 @article{lunn_lucier_rizkalla_cleland_gleich_2017, title={New generation of precast concrete double tees reinforced with carbon-fiber-reinforced polymer grid response}, journal={PCI Journal}, author={Lunn, D. and Lucier, G. and Rizkalla, S. and Cleland, N. and Gleich, H.}, year={2017}, pages={90–91} }
 @article{botros_lucier_rizkalla_gleich_2016, title={Behavior of Free and Connected Double-Tee Flanges Reinforced with carbon-fiber-reinforced polymer}, journal={PCI Journal}, author={Botros, A. and Lucier, G. and Rizkalla, S. and Gleich, H.}, year={2016}, month={Sep} }
 @article{pour-ghaz_miller_alla_rizkalla_2016, title={Do mechanical and environmental loading have a synergistic effect on the degradation of pultruded glass fiber reinforced polymers?}, volume={106}, ISSN={["1879-1069"]}, DOI={10.1016/j.compositesb.2016.09.007}, abstractNote={This paper investigates the effect of simultaneous mechanical and environmental loading on the degradation rate of pultruded Glass Fiber Reinforced Polymer (GFRP) composites. The experimental program included testing a large number of GFRP coupons, with vinylester or polyester matrices, conditioned for 1000 or 2000 h under a wide range of sustained stresses and exposed to freshwater or saltwater at an elevated temperature of 60 °C. Mechanical tests, including tensile strength and elastic modulus measurements were performed on the GFRP composites. In addition, glass transition measurements, moisture uptake measurements, scanning electron microscopy, and acoustic emission testing were performed to better understand the synergistic effect of mechanical loading and environmental conditions.}, journal={COMPOSITES PART B-ENGINEERING}, author={Pour-Ghaz, Mohammad and Miller, Bryant L. H. and Alla, Omar Khalaf and Rizkalla, Sami}, year={2016}, month={Dec}, pages={344–355} }
 @article{cholake_moran_joe_bai_raman_zhao_rizkalla_bandyopadhyay_2016, title={Improved Mode I fracture resistance of CFRP composites by reinforcing epoxy matrix with recycled short milled carbon fibre}, volume={111}, ISSN={["1879-0526"]}, DOI={10.1016/j.conbuildmat.2016.02.039}, abstractNote={This paper proves that incorporation of recycled short milled carbon fibre (SMCF) in epoxy resin can lead to the generation of significantly tougher carbon fibre reinforced polymer (CFRP) systems in a cost effective manner for infrastructural applications. Structural epoxy resin is modified by adding 5 and 10 wt.% of SMCF particles and the ‘fracture toughness’ of the modified matrix (GICM) is observed to be increased by 300% and 700% respectively. Subsequently, the SMCF modified epoxy resins were used to fabricate unidirectional carbon fibre reinforced laminates and tested under Mode I crack opening. The SMCF reinforcement showed 50% and 64% improvement in the laminates fracture toughness (GICC) after adding 5% and 10% SMCF by wt., respectively. Scanning electron microscope images of the fracture surface highlight improved debonding and pull-out mechanisms contributing to the additional fracture toughness, and at the same time there was no evidence of fibre clustering.}, journal={CONSTRUCTION AND BUILDING MATERIALS}, author={Cholake, Sagar T. and Moran, Grainne and Joe, Bill and Bai, Yu and Raman, R. K. Singh and Zhao, X. L. and Rizkalla, Sami and Bandyopadhyay, Sri}, year={2016}, month={May}, pages={399–407} }
 @article{shapack_van brunt_seracino_lucier_rizkalla_pour-ghaz_2016, title={Improving the Durability and Coastal Bridges with CFRP Prestressed Cored Slabs}, journal={ACI Special publications}, author={Shapack, G. and Van Brunt, Z. and Seracino, R. and Lucier, G. and Rizkalla, S. and Pour-Ghaz, M.}, year={2016}, month={Apr} }
 @article{lunn_lucier_rizkalla_cleland_gleich_2016, title={New generation of precast concrete double tees reinforced by carbon-fiber-reinforced polymer grid response}, journal={PCI Journal}, author={Lunn, D. and Lucier, G. and Rizkalla, S. and Cleland, N. and Gleich, H.}, year={2016}, pages={87–89} }
 @article{kazem_guaderrama_selim_rizkalla_kobayashi_2016, title={Strengthening of steel plates subjected to uniaxial compression using small-diameter CFRP strands}, volume={111}, ISSN={["1879-0526"]}, DOI={10.1016/j.conbuildmat.2016.02.028}, abstractNote={This paper presents the results of a study that was carried out to investigate the use of small-diameter CFRP strands for strengthening steel plates subjected to uniaxial compression. This study is part of a comprehensive research program to evaluate the use of the small-diameter CFRP strands for shear strengthening of steel girders. The research in this paper was undertaken to examine the bond characteristics of the proposed material which is expected to eliminate the debonding failure observed for CFRP laminates strengthening system and to resist the compressive stresses induced in high shear zones. The small-diameter CFRP strands are stitched together with a gap between the strands to allow each strand to be completely covered by the adhesive material. The effectiveness of the strengthening system was investigated by varying various parameters believed to affect the overall behavior including the slenderness ratio of the steel plates as well as mechanical properties and reinforcement ratios of the CFRP strands. Strengthened plates exhibited higher buckling capacity in comparison to similar plates without CFRP strands. In addition, the small-diameter CFRP strands did not show any signs of debonding at large lateral deformation associated with elastic buckling.}, journal={CONSTRUCTION AND BUILDING MATERIALS}, author={Kazem, Hamid and Guaderrama, Lucas and Selim, Hatem and Rizkalla, Sami and Kobayashi, Akira}, year={2016}, month={May}, pages={223–236} }
 @article{seliem_ding_potter_rizkalla_2016, title={Use of carbon-fiber-reinforced polymer grid for precast concrete piles}, journal={PCI Journal}, author={Seliem, H. and Ding, L. and Potter, W. and Rizkalla, S.}, year={2016}, month={Sep} }
 @article{kazem_bunn_seliem_rizkalla_gleich_2015, title={Durability and long term behavior of FRP/foam shear transfer mechanism for concrete sandwich panels}, volume={98}, ISSN={["1879-0526"]}, DOI={10.1016/j.conbuildmat.2015.08.105}, abstractNote={This paper presents an experimental program to evaluate the effect of sustained loading and outdoor exposure on the shear strength of precast concrete sandwich panels connected with FRP grid/rigid foam insulation as shear transfer mechanism. CFRP and GFRP grids were considered in this study along with EPS and XPS foam. The experimental program is comprised of three different studies with a total of 26 test panels using different combinations of FRP grid and foam insulation.}, journal={CONSTRUCTION AND BUILDING MATERIALS}, author={Kazem, Hamid and Bunn, William G. and Seliem, Hatem M. and Rizkalla, Sami H. and Gleich, Harry}, year={2015}, month={Nov}, pages={722–734} }
 @article{hodicky_sopal_rizkalla_hulin_stang_2015, title={Experimental and Numerical Investigation of the FRP Shear Mechanism for Concrete Sandwich Panels}, volume={19}, ISSN={["1943-5614"]}, DOI={10.1061/(asce)cc.1943-5614.0000554}, abstractNote={AbstractThis paper investigates the composite action of 46 segments representing precast concrete sandwich panels (PCSPs) using a fiber-reinforced polymer [FRP; specifically, a carbon fiber–reinforced polymer (CFRP)] grid/rigid foam as a shear mechanism. The experimental aspect of the research reported in this paper examined the effect of various parameters believed to affect the shear flow strength for this CFRP grid/foam system. The parameters that were considered are the spacing between vertical lines of CFRP grids and the thickness of the rigid foam. Results of the experimental aspect of the research reported in this paper indicated that increasing the spacing between vertical lines of CFRP grid increase the overall shear flow strengths due to the increase of the bonded contact area of the rigid foam to the concrete surface. However, the overall shear stresses were decreased due to the increase of this interface surface area. Test results also indicated that increasing the rigid foam thickness decreas...}, number={5}, journal={JOURNAL OF COMPOSITES FOR CONSTRUCTION}, author={Hodicky, K. and Sopal, G. and Rizkalla, S. and Hulin, T. and Stang, H.}, year={2015}, month={Oct} }
 @article{lunn_lucier_rizkalla_cleland_gleich_2015, title={New generation of precast concrete double tees reinforced with carbon-fiber reinforced polymer grid}, volume={60}, ISSN={0887-9672}, url={http://dx.doi.org/10.15554/pcij.07012015.37.48}, DOI={10.15554/pcij.07012015.37.48}, number={4}, journal={PCI Journal}, publisher={Precast/Prestressed Concrete Institute}, author={Lunn, Dillon and Lucier, Gregory and Rizkalla, Sami and Cleland, Ned and Gleich, Harry}, year={2015}, month={Jul}, pages={37–48} }
 @article{tabrizi_kazem_rizkalla_kobayashi_2015, title={New small-diameter CFRP material for flexural strengthening of steel bridge girders}, volume={95}, ISSN={["1879-0526"]}, DOI={10.1016/j.conbuildmat.2015.07.109}, abstractNote={This paper presents the research findings of an experimental program undertaken to examine the effectiveness of using small-diameter CFRP strands to increase the flexural capacity of steel beams and bridge girders. The experimental program included scaled steel-concrete composite beams, strengthened with these small-diameter strands. The CFRP strands were stitched together with a gap between the strands to allow the adhesive to penetrate and cover the entire perimeter of each strand. Results showed that the proposed system eliminated failure due to de-bonding of the strengthening materials and significantly increased the flexural capacity and stiffness of steel beams.}, journal={CONSTRUCTION AND BUILDING MATERIALS}, author={Tabrizi, Salar and Kazem, Hamid and Rizkalla, Sami and Kobayashi, Akira}, year={2015}, month={Oct}, pages={748–756} }
 @article{cholake_moran_bai_raman_zhao_rizkalla_bandyopadhyay_2015, title={Physico-Chemical Characterization of Novel Epoxy Matrix System Reinforced with Recycled Short Milled Carbon Fibre}, volume={03}, ISSN={2327-4077 2327-4085}, url={http://dx.doi.org/10.4236/jmmce.2015.35040}, DOI={10.4236/jmmce.2015.35040}, abstractNote={As received recycled short milled carbon fiber (SMCF) reinforced diglycidal ether of bisphenol-A 
(DGEBA) epoxy matrix materials have been developed by ultra-sonication mixing of SMCF in epoxy 
then curing at room temperature for nine days. The SMCF with mean diameter 7.5 μm, and length 
100 - 300 μm, was used at different loadings i.e. 1, 2, 3, 5 and 10 wt%. Elemental analysis, surface 
chemistry and crystallography of SMCF were examined using X-ray fluorescence, X-ray photoelectron 
spectroscopy and X-ray diffraction. Fourier Transform IR spectroscopy confirmed that both 
in unmodified and SMCF-modified epoxies, 99% curing was achieved. Surface microhardness 
study showed a slight increase with 5% and 10% SMCF addition. Raman study confirms no structural 
change in SMCF after incorporation in epoxy. Also, a numerical modelling is implemented to 
correlate the density of the modified epoxy and SMCF volume fraction/distribution uniformity.}, number={05}, journal={Journal of Minerals and Materials Characterization and Engineering}, publisher={Scientific Research Publishing, Inc,}, author={Cholake, Sagar T. and Moran, Grainne and Bai, Yu and Raman, R. K. Singh and Zhao, X. L. and Rizkalla, Sami and Bandyopadhyay, Sri}, year={2015}, pages={373–389} }
 @article{high_seliem_el-safty_rizkalla_2015, title={Use of basalt fibers for concrete structures}, volume={96}, ISSN={0950-0618}, url={http://dx.doi.org/10.1016/J.CONBUILDMAT.2015.07.138}, DOI={10.1016/J.CONBUILDMAT.2015.07.138}, abstractNote={This study investigated the use of basalt fiber bars as flexural reinforcement for concrete members and the use of chopped basalt fibers as an additive to enhance the mechanical properties of concrete. The material characteristics and development length of two commercially-available basalt fiber bars were evaluated. Test results indicate that flexural design of concrete members reinforced with basalt fiber bars should ensure compression failure and satisfying the serviceability requirements. ACI 440.1R-06 accurately predicts the flexural capacity of members reinforced with basalt bars, but it significantly underestimates the deflection at service load level. Use of chopped basalt fibers had little effect on the concrete compressive strength; however, significantly enhanced its flexural modulus.}, journal={Construction and Building Materials}, publisher={Elsevier BV}, author={High, Cory and Seliem, Hatem M. and El-Safty, Adel and Rizkalla, Sami H.}, year={2015}, month={Oct}, pages={37–46} }
 @article{lunn_rizkalla_2014, title={Design of FRP-Strengthened Infill Masonry Walls Subjected to Out-of-Plane Loading}, volume={18}, ISSN={["1943-5614"]}, DOI={10.1061/(asce)cc.1943-5614.0000412}, abstractNote={AbstractFiber-reinforced polymer (FRP) strengthening systems for infill-masonry walls are typically designed to resist flexural stresses caused by out-of-plane pressure. Previous research has shown that there are potential premature failure mechanisms caused by shear sliding of the infill, which could reduce the effectiveness of the strengthening system. Current design guidelines for strengthening of masonry walls with FRP do not include guidelines for infill-masonry. This paper presents a rational approach for the design and analysis of FRP-strengthened infill-masonry walls subjected to out-of-plane loading, including the effect of using FRP end anchorage. The approach is based on consideration of four potential mechanisms: arching, shear sliding, debonding of the FRP in the overlap region, and failure of the FRP end-anchorage system. The predictions based on the proposed rational approach agree well with the measured values from two experimental programs.}, number={3}, journal={Journal of Composites for Construction}, author={Lunn, D. and Rizkalla, S.}, year={2014}, month={Jun} }
 @misc{zhao_bai_al-mahaidi_rizkalla_2014, title={Effect of Dynamic Loading and Environmental Conditions on the Bond between CFRP and Steel: State-of-the-Art Review}, volume={18}, ISSN={["1943-5614"]}, DOI={10.1061/(asce)cc.1943-5614.0000419}, abstractNote={AbstractCarbon fiber reinforced polymer (CFRP) has great potential in strengthening steel structures and the bond between CFRP and steel is a critical issue in the strengthening technique. State-of-the-art reviews have been reported in the literature on the bond behavior between CFRP and steel under static loading at ambient temperature. However, steel structures are often subjected to dynamic loading and harsh environment conditions, and the bond between CFRP and steel may be affected by these conditions. This paper presents a state-of-the-art review on the effects of dynamic loading (e.g., fatigue, impact, and earthquake) and environmental conditions (e.g., subzero temperatures, elevated temperatures, sea water, and ultraviolet light) on the bond between CFRP and steel. The combined effect of applied loading and environmental conditions is also included. Directions for future research are indicated and a comprehensive reference list is provided.}, number={3}, journal={JOURNAL OF COMPOSITES FOR CONSTRUCTION}, author={Zhao, Xiao-Ling and Bai, Yu and Al-Mahaidi, Riadh and Rizkalla, Sami}, year={2014}, month={Jun} }
 @article{cholake_mada_raman_bai_zhao_rizkalla_bandyopadhyay_2014, title={Quantitative Analysis of Curing Mechanisms of Epoxy Resin by Mid- and Near-Fourier Transform Infra Red Spectroscopy}, volume={64}, ISSN={["0976-464X"]}, DOI={10.14429/dsj.64.7326}, abstractNote={This article informs the essence of major work done by a number of researchers on the analysis of two-step curing mechanism of diglycidyl ether of bisphenol A (DGEBA) epoxy resin in presence of amine curing agents using near- and mid-IR technology. Various peaks used as a marker for resin formation are discussed and their implementation is comprehensively studied. In addition to this, a wide range of information about the importance of reference peaks in both near-IR (NIR) and mid-IR (MIR) regions are congregated and their accuracy is audited. Also discrepancies observed by researchers in epoxy conversion (α) in NIR and MIR regions are reviewed to highlight the comparative advantages of both regions, one over the other. Defence Science Journal, Vol. 64, No. 3, May 2014, pp. 314-321, DOI:http://dx.doi.org/10.14429/dsj.64.7326}, number={3}, journal={DEFENCE SCIENCE JOURNAL}, author={Cholake, Sagar T. and Mada, Mykanth R. and Raman, R. K. Singh and Bai, Yu and Zhao, X. L. and Rizkalla, Sami and Bandyopadhyay, Sri}, year={2014}, month={May}, pages={314–321} }
 @article{liu_zhao_bai_singh_rizkalla_bandyopadhyay_2014, title={The Effect of Elevated Temperature on the Bond Between High Modulus Carbon Fibre-Reinforced Polymer Sheet and Steel}, volume={15}, DOI={10.7158/13287982.2014.11465170}, abstractNote={Abstract The technique of strengthening steel structures with carbon fibre-reinforced polymer (CFRP) has attracted growing attention in research field and in practice, and thus, its environmental durability is of high importance. This paper describes an investigation on the bond characteristics between high modulus CFRP sheets and steel plates under elevated temperature exposures. Tensile tests were carried out on CFRP/steel plate double strap joints at different temperatures (20,40 and 50 °C) that represent the usually encountered conditions for civil infrastructure. High modulus (640 GPa) unidirectional carbon fibre sheets were applied by wet lay-up fabrication method. The fracture surfaces of the failed specimens were studied using a scanning electron microscope and the failure mechanisms were discussed. It was found that the ultimate load decreased significantly when the test temperature was above the glass transition temperature of the adhesive. Larger effective bond lengths were found for the joints tested at the glass transition temperature. It is obvious that the short-term thermal exposure has little effect on their failure patterns. All the specimens failed by fibre breakage at the joint and decohesion accompanied some joints with very short bond length.}, number={4}, journal={Australian Journal of Structural Engineering}, author={Liu, H. and Zhao, X. and Bai, Y. and Singh, R. and Rizkalla, S. and Bandyopadhyay, S.}, year={2014}, month={Jul}, pages={355–366} }
 @article{lunn_maeda_rizkalla_ueda_2013, title={Anchorage Systems for FRP Strengthening of Infill Masionry Structures}, volume={1}, number={2}, journal={International Journal of Sustainable Materials and Structural Systems}, author={Lunn, D. and Maeda, S. and Rizkalla, S. and Ueda, T.}, year={2013}, month={Sep}, pages={142–160} }
 @article{storm_rizkalla_zia_2013, title={Effects of production practices on camber of prestressed concrete bridge girders Response}, journal={PCI Journal}, author={Storm, T. K. and Rizkalla, S. H. and Zia, P. Z.}, year={2013}, pages={143–144} }
 @article{rizkalla_lunn_lucier_sennour_gleich_carson_2013, title={Innovative Use of FRP for Sustainable Precast Structures}, number={8}, journal={Precast Concrete Façade Tectonics Journal}, author={Rizkalla, S. and Lunn, D. and Lucier, G. and Sennour, L. and Gleich, H. and Carson, J.}, year={2013}, month={Feb}, pages={55–63} }
 @article{rizkalla_lunn_lucier_sennour_gleich_2013, title={Precast Concrete Wall Panels}, journal={Journal of the Concrete Plant International Journal}, author={Rizkalla, S. and Lunn, D. and Lucier, G. and Sennour, L. and Gleich, H.}, year={2013}, month={Mar} }
 @article{lucier_sennour_rizkalla_2013, title={Structural Composites Thermally Efficient Precast Concrete}, volume={2}, number={1}, journal={Concrete Plant International, CPI}, author={Lucier, G. and Sennour, L. and Rizkalla, S.}, year={2013}, pages={1–10} }
 @article{klein_lucier_rizkalla_zia_gleich_2013, title={Torsion Simplified: A Failure Plan Model for Design of Spandrel Beams}, volume={110}, number={5}, journal={ACI Structural Journal}, author={Klein, G.L. and Lucier, G. and Rizkalla, S. and Zia, P. and Gleich, H.}, year={2013}, month={Oct} }
 @article{hassan_mantawy_soliman_sherif_rizkalla_2012, title={Bond Characteristics and Shear Behavior of Concrete Beams Reinforced with High-Strength Steel Reinforcement}, volume={15}, ISSN={["1369-4332"]}, DOI={10.1260/1369-4332.15.2.303}, abstractNote={This paper evaluates the bond behavior of high strength (HS), steel reinforcing bars and highlights the effect of various key parameters believed to affect the bond characteristics. Nine reinforced concrete spliced beams were constructed and tested. The beams had different splice lengths and levels of confinements. The applicability of different hypotheses for development of conventional steel bars was examined for the HS bars. The study is extended to examine the behavior of the reinforcing bars as shear reinforcement for concrete beams by testing twelve concrete beams reinforced with HS steel stirrups under static loading conditions. The main variables in the study included steel type, concrete compressive strength, web reinforcement ratio and shear span-to-depth ratio. The applicability of various building codes and standards for concrete beams with HS shear reinforcement was also evaluated.}, number={2}, journal={ADVANCES IN STRUCTURAL ENGINEERING}, author={Hassan, Tarek K. and Mantawy, Ahmed and Soliman, Judy and Sherif, Ali and Rizkalla, Sami H.}, year={2012}, month={Feb}, pages={303–318} }
 @article{hosny_seliem_rizkalla_zia_2012, title={Development length of unconfined conventional and high-strength steel reinforcing bars}, volume={109}, DOI={10.14359/51684043}, abstractNote={The development length equation specified by ACI 318-08 and the similar equation recommended by ACI 408R-03 are based on extensive test results using conventional reinforcement conforming to ASTM A615/A615M and A706/A706M. With the development of new ASTM A1035/A1035M high-strength steel reinforcement, several studies have been conducted to examine whether the current equations are applicable for the new high-strength reinforcing steel. These studies have shown that the current equations could, in some cases, overestimate the bond strength of high-strength steel bars. This paper proposes a new equation for the bond strength of unconfined reinforcing bars for all three types of steel. The proposed equation for high-strength steel is compared to extensive test data reported in the literature and is found to be more accurate than ACI 318-08 and ACI408R-03 equations specified for conventional reinforcement.}, number={5}, journal={ACI Structural Journal}, author={Hosny, A. and Seliem, H. M. and Rizkalla, S. H. and Zia, P.}, year={2012}, pages={655–664} }
 @article{klein_rizkalla_zia_lucier_2012, title={Development of a rational design methodology for precast concrete slender spandrel beams}, journal={PCI Journal}, author={Klein, G. and Rizkalla, S. and Zia, P. and Lucier, G.}, year={2012}, pages={182–186} }
 @article{mosavi_seracino_rizkalla_2012, title={Effect of Temperature on Daily Modal Variability of a Steel-Concrete Composite Bridge}, volume={17}, ISSN={["1084-0702"]}, DOI={10.1061/(asce)be.1943-5592.0000372}, abstractNote={Vibration-based damage detection techniques typically use changes of modal characteristics of bridges as a possible indication of damage. However, structural damages are not the only cause of these changes. This study investigates the effect of temperature variations on modal characteristics of a two span steel-concrete composite bridge in North Carolina, and addresses the extent and reason of the daily changes observed in its dynamic properties. The field testing included measuring vibration responses, deflections, and temperatures of the bridge throughout a summer day. The dynamic characteristics of the bridge, derived from measurements at different times of the day, were compared with each other. Recorded temperatures and deflections of the bridge deck were used to address the observed changes in the natural frequencies of the bridge. Results of the field testing showed that temperature variations can induce modal variability on a daily cycle. A primary reason for this observation can be attributed to the temperature gradients measured on the bridge deck from night to noon.}, number={6}, journal={JOURNAL OF BRIDGE ENGINEERING}, author={Mosavi, Amir A. and Seracino, Rudolf and Rizkalla, Sami}, year={2012}, pages={979–983} }
 @article{mosavi_dickey_seracino_rizkalla_2012, title={Identifying damage locations under ambient vibrations utilizing vector autoregressive models and Mahalanobis distances}, volume={26}, ISSN={["0888-3270"]}, DOI={10.1016/j.ymssp.2011.06.009}, abstractNote={This paper presents a study for identifying damage locations in an idealized steel bridge girder using the ambient vibration measurements. A sensitive damage feature is proposed in the context of statistical pattern recognition to address the damage detection problem. The study utilizes an experimental program that consists of a two-span continuous steel beam subjected to ambient vibrations. The vibration responses of the beam are measured along its length under simulated ambient vibrations and different healthy/damage conditions of the beam. The ambient vibration is simulated using a hydraulic actuator, and damages are induced by cutting portions of the flange at two locations. Multivariate vector autoregressive models were fitted to the vibration response time histories measured at the multiple sensor locations. A sensitive damage feature is proposed for identifying the damage location by applying Mahalanobis distances to the coefficients of the vector autoregressive models. A linear discriminant criterion was used to evaluate the amount of variations in the damage features obtained for different sensor locations with respect to the healthy condition of the beam. The analyses indicate that the highest variations in the damage features were coincident with the sensors closely located to the damages. The presented method showed a promising sensitivity to identify the damage location even when the induced damage was very small.}, journal={MECHANICAL SYSTEMS AND SIGNAL PROCESSING}, author={Mosavi, A. A. and Dickey, D. and Seracino, R. and Rizkalla, S.}, year={2012}, month={Jan}, pages={254–267} }
 @article{rizkalla_lucier_dawood_2012, title={Innovative Use of FRP for the Precast Industry}, volume={15}, ISSN={["2048-4011"]}, DOI={10.1260/1369-4332.15.4.565}, abstractNote={This paper presents several advancements in the use of fiber reinforced polymer (FRP) materials for the precast concrete industry. Precast concrete members are commonly selected for reasons such as the high level of quality control used in their production, the durability of the finished structure, reduced labor costs and shorter construction schedules, and the economics of scale achieved with mass-production of components. The environmental durability, high strength to weight ratio, and ease of installation of FRP reinforcements an attractive alternative material for the precast industry. This paper presents several advancements in the use of FRP grid as flange reinforcement for precast double-tee members, as a shear transfer mechanism for thermally efficient composite and partially-composite load bearing wall panels, as reinforcement for precast architectural cladding panels. Each of these applications highlights the advantages of using FRP materials to achieve significant enhancement of the structural, thermal and architectural performance. The innovative use of the FRP materials and the unique construction techniques described have resulted in the development of safe and functional structures, as demonstrated by the research conducted by the authors and others in collaboration with the precast industry.}, number={4}, journal={Advances in Structural Engineering Journal}, author={Rizkalla, S. and Lucier, G. and Dawood, M.}, year={2012}, month={Apr}, pages={565–574} }
 @article{ding_seliem_rizkalla_2011, title={Behavior of Concrete Piles Confined with CFRP}, number={275}, journal={ACI Special Publication}, author={Ding, L. and Seliem, H.M. and Rizkalla, S.}, year={2011}, month={Apr}, pages={275–311} }
 @article{frankl_lucier_hassan_rizkalla_2011, title={Behavior of Insulated Precast, Prestressed Concrete Sandwich Wall Panels Reinforced with CFRP Grid}, volume={56}, number={2}, journal={PCI Journal}, author={Frankl, B. and Lucier, G. and Hassan, T. and Rizkalla, S.}, year={2011}, pages={88–111} }
 @article{heiser_hosny_rizkalla_zia_2011, title={Bond and shear behavior of concrete beams containing lightweight synthetic particles}, volume={108}, DOI={10.14359/51683368}, abstractNote={Adding lightweight synthetic particles (LSP) to a concrete mixture can reduce the pumping pressure of fresh concrete, reduce the unit weight of concrete by as much as 10-20%, and improve the thermal resistance of the hardened concrete. This paper describes an experimental program that investigated the bond and shear behavior of concrete beams containing LSP. The experimental program included 27 large-scale specimens. Results indicate that the bond and shear behavior of beams with LSP additive is similar to the behavior of beams made with normalweight concrete. The results also confirm that ACI 318-08 can be used for the design of LSP concrete members for shear and the development length of steel reinforcement without the use of the reduction factor λ required for lightweight concrete. Limitations of this study and directions for future investigation are discussed.}, number={6}, journal={ACI Structural Journal}, author={Heiser, M. J. and Hosny, A. and Rizkalla, S. H. and Zia, P.}, year={2011}, pages={698–705} }
 @article{lucier_walter_rizkalla_zia_klein_2011, title={Development of a rational design methodology for precast concrete slender spandrel beams: Part 1, experimental results}, volume={56}, ISSN={0887-9672}, url={http://dx.doi.org/10.15554/pcij.03012011.88.112}, DOI={10.15554/pcij.03012011.88.112}, abstractNote={This paper summarizes test results of an extensive experimental program undertaken to develop a rational design procedure for precast concrete slender spandrel beams. Experimental research findings presented in this paper are used to propose a rational design procedure that will be presented in a forthcoming companion paper. The research introduced significantly simplified detailing requirements for the end regions of precast concrete slender spandrel beams. Such regions are often congested with heavy reinforcing cages when designed according to current procedures. In total, 16 full-scale precast concrete spandrel beams were tested to failure to study the limit state behavior. Each specimen was loaded through full-scale double-tee deck sections to mimic typical field conditions. Three of the specimens were designed and detailed with closed stirrups, according to current practice, and served as controls for the experimental program. The remaining thirteen specimens were designed with various configurations of open web reinforcement. Several specimens were specially configured with flexural, ledge/corbel, and hanger reinforcement in excess of what would be provided in a normal design. The enhanced reinforcement helped to delay typical midspan and local failure modes and allowed for observation and study of failure modes in the end region. The experimental results, combined with the analytical results and rational modeling in the companion paper, demonstrate that properly designed open web reinforcement is a safe, effective, and efficient alternative to traditional closed stirrups for precast concrete slender spandrel beams that have an aspect ratio of 4.6 or greater.}, number={2}, journal={PCI Journal}, publisher={Precast/Prestressed Concrete Institute}, author={Lucier, Gregory and Walter, Catrina and Rizkalla, Sami and Zia, Paul and Klein, Gary}, year={2011}, month={Mar}, pages={88–112} }
 @article{lucier_walter_rizkalla_zia_klein_2011, title={Development of a rational design methodology for precast concrete slender spandrel beams: Part 2, analysis and design guidelines}, DOI={10.15554/pcij.09012011.106.133}, abstractNote={This paper summarizes the results of an analytical research program undertaken to develop a rational design procedure for normalweight precast concrete slender spandrel beams. The analytical and rational models use test results and research findings of an extensive experimental program presented in the companion paper "Development of a Rational Design Methodology for Precast Concrete Slender Spandrel Beams: Part 1, Experimental Results," which appeared in the Spring 2011 issue of PCI Journal. The overall research effort demonstrated the validity of using open web reinforcement in precast concrete slender spandrel beams and proposed a simplified procedure for design. The webs of such slender spandrels, particularly in their end regions, are often heavily congested with reinforcing cages when designed with current procedures. The experimental and analytical results demonstrate that open web reinforcement designed according to the proposed procedure is safe and effective and provides an efficient alternative to traditional closed stirrups for precast concrete slender spandrel beams.}, journal={PCI Journal}, author={Lucier, Gregory and Walter, C. and Rizkalla, S. and Zia, P. and Klein, G.}, year={2011}, pages={106–133} }
 @article{el-hacha_mirmiran_cook_rizkalla_2011, title={Effectiveness of Surface-Applied Corrosion Inhibitors for Concrete Bridges}, volume={23}, ISSN={0899-1561 1943-5533}, url={http://dx.doi.org/10.1061/(ASCE)MT.1943-5533.0000163}, DOI={10.1061/(ASCE)MT.1943-5533.0000163}, abstractNote={While the effectiveness of corrosion-inhibiting admixtures in new concrete has been well documented, there is little research on their surface-applied counterparts for existing structures. This study was undertaken to assess whether surface-applied products can delay, slow, or stop the corrosion process in contaminated concrete. A total of 348 specimens were tested using six commercially available corrosion inhibitors, at six levels of initial chloride content, and under two accelerated corrosive environments of salt-water spray and wet-dry cycles. Half of the specimens were intentionally cracked before applying the inhibitors, while the others were cracked afterward. Corrosion current and half-cell potential readings were taken weekly during the environmental exposure. Corroded bars were then assessed visually for surface rust and rib loss; and their mass loss and strength reduction were measured. Progression of chloride content over time was measured using companion concrete cubes. The inhibitors generally delayed the onset of corrosion and slowed the process, up to an initial chloride content of 0.5% by weight of cement. Each product seemed effective up to an extent in exposure time and the chloride content. However, no product stopped the corrosion process, and none purged chloride ions. The products may be most effective as preventive measures for fully hardened "virgin" concrete with initial chloride content below those specified to induce corrosion.}, number={3}, journal={Journal of Materials in Civil Engineering}, publisher={American Society of Civil Engineers (ASCE)}, author={El-Hacha, Raafat and Mirmiran, Amir and Cook, Anna and Rizkalla, Sami}, year={2011}, month={Mar}, pages={271–280} }
 @article{soong_raghavan_rizkalla_2011, title={Fundamental mechanisms of bonding of glass fiber reinforced polymer reinforcement to concrete}, volume={25}, ISSN={["1879-0526"]}, DOI={10.1016/j.conbuildmat.2010.12.054}, abstractNote={Fundamental mechanisms of bonding between glass fiber reinforced polymer (GFRP) bar and concrete are presented. Contributions from chemical bonding, bearing resistance, and frictional resistance to bond were delineated by measuring the following: the load corresponding to complete debonding of the bar, the load corresponding to onset of sliding and pullout of the bar along the entire embedment length, and the frictional load corresponding to frictional resistance to sliding. Research findings indicate that while chemical bonding was the main contributor to the interfacial bond strength, the other two mechanisms contributed to the pullout strength of the bar. Correlation between the bar’s surface geometry and the contributions from the three mechanisms are discussed.}, number={6}, journal={CONSTRUCTION AND BUILDING MATERIALS}, author={Soong, Wai How and Raghavan, J. and Rizkalla, Sami H.}, year={2011}, month={Jun}, pages={2813–2821} }
 @article{obregon-salinas_rizkalla_zia_2011, title={Grancrete as Adhesive for FRP Flexural Strengthening System for Concrete Structures}, journal={ACI Special Publication}, author={Obregon-Salinas, A.J. and Rizkalla, S. and Zia, P.}, year={2011}, month={Apr} }
 @article{hassan_lucier_rizkalla_2011, title={Splice strength of large diameter, high strength steel reinforcing bars}, volume={7}, ISSN={0950-0618}, url={http://dx.doi.org/10.1016/j.conbuildmat.2011.06.013}, DOI={10.1016/j.conbuildmat.2011.06.013}, abstractNote={The results of an experimental program conducted to study the splice strength of large diameter, high strength reinforcing bars, either No. 20 (63.5 mm diameter) or No. 9 (28 mm diameter), are presented. The parameters included in the experimental program are the bar size, splice length, concrete compressive strength, and the amount of transverse reinforcement provided within the splice zone. The ability of several models including the current ACI 318 Building Code, to predict the maximum steel stresses at the onset of splitting failure was examined for these high strength, large diameter bars. The influence of the moment of inertia of the bar on the induced splitting stresses was evaluated numerically using finite element analysis. Test results showed that the presence of transverse reinforcement has a more pronounced effect for large diameter spliced-bars compared to regular size bars. It is also shown that the current ACI 318 Building Code provided more conservative bond strength predictions for regular bars compared to large diameter bars.}, journal={Construction and Building Materials}, publisher={Elsevier BV}, author={Hassan, Tarek K. and Lucier, Gregory W. and Rizkalla, Sami H.}, year={2011}, month={Jul} }
 @article{lunn_rizkalla_2011, title={Strengthening of Infill Masonry Walls with FRP Materials}, volume={15}, ISSN={["1943-5614"]}, DOI={10.1061/(asce)cc.1943-5614.0000088}, abstractNote={This paper evaluates the effectiveness of different externally bonded glass fiber–reinforced polymer (GFRP) systems for increasing the out-of-plane resistance of infill masonry walls to loading. The research included a comprehensive experimental program comprising 14 full-scale specimens, including four unstrengthened (control) specimens and 10 strengthened specimens. To simulate the boundary conditions of infill walls, all specimens consisted of a reinforced concrete (RC) frame, simulating the supporting RC elements of a building superstructure, which was infilled with solid concrete brick masonry. The specimens were loaded out-of-plane using uniformly distributed pressure to simulate the differential (suction) pressure induced by a tornado. Parameters investigated in the experimental program included aspect ratio, FRP coverage ratio, number of masonry wythes, and type of FRP anchorage. Test results indicated that the type of FRP anchorage had a significant effect on the failure mode. Research findings c...}, number={2}, journal={JOURNAL OF COMPOSITES FOR CONSTRUCTION}, author={Lunn, Dillon S. and Rizkalla, Sami H.}, year={2011}, pages={206–214} }
 @article{hassan_rizkalla_2010, title={Analysis and design guidelines of precast, prestressed concrete, composite load-bearing sandwich wall panels reinforced with CFRP grid}, volume={55}, ISSN={0887-9672}, url={http://dx.doi.org/10.15554/pcij.03012010.147.162}, DOI={10.15554/pcij.03012010.147.162}, abstractNote={This paper presents newly developed design guidelines for precast/prestressed concrete wall panels reinforced with carbon-fiber-reinforced-polymer (CFRP) shear grid to achieve the composite interaction. The analytical approach provides a general methodology to determine the behavior of fully and partially composite wall panels. The effects of an imperfect connection between the two concrete wythes are considered by varying the total shear force transmitted through the shear connectors at the interface. The predicted strains along the thickness of the panel at different load levels compared well with recent test results conducted at North Carolina State University in Raleigh. The shear-flow capacity of the insulating materials and the CFRP shear grid are determined using the proposed approach. The influence of the degree of the composite interaction on the induced curvature and slip-strain behavior is presented. A simple design chart for estimating the flexural capacity of the wall panels with different shear-reinforcement ratios is proposed. The approach is also verified by using finite-element analysis up to the service-load level. The predicted displacement and strains compared well with the measured values reported by the experimental program.}, number={2}, journal={PCI Journal}, publisher={Precast/Prestressed Concrete Institute}, author={Hassan, Tarek K. and Rizkalla, Sami H.}, year={2010}, month={Mar}, pages={147–162} }
 @article{schnerch_rizkalla_2010, title={Closure to "Flexural Strengthening of Steel Bridges with High Modulus CFRP Strips" by David Schnerch and Sami Rizkalla}, volume={15}, ISSN={["1943-5592"]}, DOI={10.1061/(asce)be.1943-5592.0000062}, number={1}, journal={JOURNAL OF BRIDGE ENGINEERING}, author={Schnerch, David and Rizkalla, Sami}, year={2010}, pages={118–118} }
 @article{mertol_rizkalla_zia_mirmiran_2010, title={Creep and shrinkage behavior of high-strength concrete and minimum reinforcement ratio for bridge columns}, volume={55}, ISSN={0887-9672}, url={http://dx.doi.org/10.15554/pcij.06012010.138.154}, DOI={10.15554/pcij.06012010.138.154}, abstractNote={This paper summarizes the findings of an extensive research program that examined the shrinkage and creep behavior of high-strength concrete (HSC) up to a strength of 18 ksi (124 MPa). Creep and shrinkage strains of 60 specimens were monitored for up to 2 years. The variables considered in this research were the concrete compressive strength, specimen size, curing type, age of concrete at loading, and loading stress level. Findings indicate that the current American Association of State Highway and Transportation Officials' (AASHTO) LRFD Bridge Design Specifications could be used to estimate the creep coefficient and shrinkage strain of HSC up to 15 ksi (103 MPa). However, the current AASHTO LRFD specifications do not provide appropriate predictions for concrete compressive strength greater than 15 ksi (103 MPa). A revised time-development correction factor is proposed to obtain better predictions for HSC up to 18 ksi (124 MPa). For HSC compression members, the current AASHTO LRFD specifications require an excessive amount of minimum longitudinal reinforcement to account for the long-term effects due to shrinkage and creep. Based on an analysis, a new relationship is proposed for the required minimum reinforcement ratio.}, number={3}, journal={PCI Journal}, publisher={Precast/Prestressed Concrete Institute}, author={Mertol, Halit Cenan and Rizkalla, Sami and Zia, Paul and Mirmiran, Amir}, year={2010}, month={Jun}, pages={138–154} }
 @article{zia_rizkalla_mirmiran_russell_mast_2010, title={Discussion on Elastic Modulus, Shrinkage and Creep of High-Strength Concrete as adopted by AASHTO}, volume={55}, number={2}, journal={PCI Journal}, author={Zia, P. and Rizkalla, S. and Mirmiran, A. and Russell, H. and Mast, R.}, year={2010}, pages={11–14} }
 @article{dawood_rizkalla_2010, title={Environmental durability of a CFRP system for strengthening steel structures}, volume={24}, ISSN={["1879-0526"]}, DOI={10.1016/j.conbuildmat.2010.02.023}, abstractNote={Recently a high modulus CFRP system was developed to enhance the load carrying capacity and serviceability of steel bridges and structures. However, the environmental durability of the system has not yet been demonstrated. This paper presents the findings of a research program that was conducted to evaluate the environmental durability of the bond of the proposed CFRP strengthening system to steel surfaces. The program consisted of testing 44 steel-CFRP double-lap shear specimens. The specimens were exposed to severe environmental conditions for different durations, up to 6 months. Different methods to enhance the bond durability were studied including pre-treating the steel surface with a silane coupling agent, inserting a glass fiber layer within the adhesive and a combination of both methods of protection. The research findings indicate that the use of a silane coupling agent significantly enhanced the bond durability. While the presence of the glass fibers helped to enhance the initial bond strength of the system, it did not improve the durability of the bond. The use of both techniques enhanced both the overall bond strength and the environmental durability of the strengthening system.}, number={9}, journal={CONSTRUCTION AND BUILDING MATERIALS}, author={Dawood, Mina and Rizkalla, Sami}, year={2010}, month={Sep}, pages={1682–1689} }
 @article{jiang_dawood_peters_rizkalla_2010, title={Global and Local Fiber Optic Sensors for Health Monitoring of Civil Engineering Infrastructure Retrofit with FRP Materials}, volume={9}, ISSN={["1741-3168"]}, DOI={10.1177/1475921709352989}, abstractNote={Fiber-reinforced polymer (FRP) materials are currently used for strengthening civil engineering structures and bridges. The effectiveness of the strengthening system is highly dependent on the bond characteristics of the FRP material to the external surface of the structure. This article presents the application of two types of fiber optic sensors, which can be embedded in FRP materials to monitor the global and local behavior of the strengthened structure, respectively. The global sensor is designed to evaluate the overall condition of a structure based on the measured elongation of the FRP layer along the entire span of the structure. The success of this low-cost global sensor has been demonstrated using a full-scale prestressed concrete bridge girder that was loaded up to failure. The test results indicate that this type of sensor can be used to identify major changes in the overall behavior of the structure such as cracking of prestressed members or yielding of the internal reinforcement. The second sensor component consists of fiber Bragg grating sensors. The sensors were used to monitor the behavior of steel double-lap shear specimens tested under tensile loading up to failure. The measurements were used to identify abnormal structural behaviors such as epoxy cracking and/or FRP debonding. The test results compared well to the numerical values obtained from a three dimensional shear-lag model that was previously developed to predict the sensor response.}, number={4}, journal={STRUCTURAL HEALTH MONITORING-AN INTERNATIONAL JOURNAL}, author={Jiang, Guoliang and Dawood, Mina and Peters, Kara and Rizkalla, Sami}, year={2010}, month={Jul}, pages={309–322} }
 @article{dawood_taylor_ballew_rizkalla_2010, title={Static and fatigue bending behavior of pultruded GFRP sandwich panels with through-thickness fiber insertions}, volume={41}, ISSN={["1879-1069"]}, DOI={10.1016/j.compositesb.2010.02.006}, abstractNote={This paper presents the findings of a research program that was undertaken to evaluate the static and fatigue characteristics of an innovative 3-D glass fiber reinforced polymer (GFRP) sandwich panel proposed for civil infrastructure and transportation applications. The research consists of analytical modeling verified by experimental results. A rational analytical model is presented and used to evaluate the effective elastic modulus, shear modulus and degree of composite interaction of the panels to resist one-way bending. The experimental program was conducted in two phases to study the static and fatigue behavior of the panels. In the first phase a total of 730 sandwich beams were tested to evaluate the effect of different parameters on the fundamental behavior of the panel. The parameters considered include the pattern and density of through-thickness fiber insertions, the overall thickness of the panels, and the number of FRP plies in the face skins. The study indicates that the shear behavior and degree of composite interaction of the panels is sensitive to the configuration of the panel core. The second phase of the experimental program included testing of 24 additional sandwich panels to evaluate the fatigue behavior. The results of the experimental program indicate that the panels with stiffer cores generally exhibited a higher degree of degradation than panels with more flexible cores. The findings of this study indicate that the proposed panels represent a versatile construction system which can be configured to achieve the specific design demands for civil engineering infrastructure applications.}, number={5}, journal={COMPOSITES PART B-ENGINEERING}, author={Dawood, M. and Taylor, E. and Ballew, W. and Rizkalla, S.}, year={2010}, month={Jul}, pages={363–374} }
 @inproceedings{mosavi_dickey_seracino_rizkalla_2010, title={Time-series models for identifying damage location in structural members subjected to ambient vibrations}, volume={7650}, booktitle={Health monitoring of structural and biological systems 2010, pts 1 and 2}, author={Mosavi, A. A. and Dickey, D. and Seracino, R. and Rizkalla, S. H.}, year={2010} }
 @article{dawood_taylor_rizkalla_2010, title={Two-way bending behavior of 3-D GFRP sandwich panels with through-thickness fiber insertions}, volume={92}, ISSN={["1879-1085"]}, DOI={10.1016/j.compstruct.2009.09.040}, abstractNote={This paper presents the details of a research program that was conducted to evaluate the two-way bending behavior of 3-D glass fiber reinforced polymer (GFRP) sandwich panels. The panels consist of GFRP skins with a foam core and through-thickness fiber insertions. While the behavior of these panels under one-way bending is relatively well understood the behavior under two-way bending has not yet been investigated. An experimental program was conducted to evaluate the effect of the fiber insertion pattern and the panel thickness on the two-way bending behavior under the effect of a concentrated load. The experimental results were used to verify a non-linear, static finite element model which was used to introduce a simplified method to predict the behavior. The measured and predicted responses indicate that at lower deflections the panel behavior is dominated by plate bending action while for higher deflections membrane action dominates. The finite element analysis was extended to study the effect of different parameters which were not tested in the experimental program. The parametric study indicates that increasing the relative flexural or shear rigidities of the panel alters the behavior towards the plate bending mechanism thereby reducing the percentage of load carried by membrane action.}, number={4}, journal={COMPOSITE STRUCTURES}, author={Dawood, M. and Taylor, E. and Rizkalla, S.}, year={2010}, month={Mar}, pages={950–963} }
 @article{munikrishna_hosny_rizkalla_zia_2010, title={behavior of concrete beams reinforced with ASTM A1035 grade 100 stirrups under shear}, volume={108}, number={1}, journal={ACI Structural Journal}, author={Munikrishna, A. and Hosny, A. and Rizkalla, S. and Zia, P.}, year={2010}, pages={34–41} }
 @article{sumpter_rizkalla_zia_2009, title={Behavior of high-performance steel as shear reinforcement for concrete beams}, volume={106}, number={2}, journal={ACI Structural Journal}, author={Sumpter, M. S. and Rizkalla, S. H. and Zia, P.}, year={2009}, pages={171–177} }
 @article{lanier_schnerch_rizkalla_2009, title={Behavior of steel monopoles strengthened with high-modulus CFRP materials}, volume={47}, ISSN={["1879-3223"]}, DOI={10.1016/j.tws.2008.10.010}, abstractNote={This paper introduces a strengthening technique for steel monopole towers using high-modulus carbon fiber reinforced polymer (CFRP) materials. The technique is based on a theoretical and analytical investigation including testing large scale steel monopole towers strengthened with different CFRP materials and connection details. Based on the research findings, design aspects and installation procedures are introduced. The recommended installation procedure describes the surface preparation, application of the adhesives and the sequence of CFRP application. The design aspects are based on flexural elastic analysis and material properties of the CFRP and steel monopole shaft. This paper recommends specific connection details to ensure the development of the forces from the CFRP to the steel tower baseplate. The research findings conclude that CFRP materials provide a viable alternative for strengthening steel monopoles that can be easily designed and installed to increase their flexural strength and stiffness.}, number={10}, journal={THIN-WALLED STRUCTURES}, author={Lanier, B. and Schnerch, D. and Rizkalla, S.}, year={2009}, month={Oct}, pages={1037–1047} }
 @article{seliem_hosny_rizkalla_zia_briggs_miller_darwin_browning_glass_hoyt_et al._2009, title={Bond characteristics of ASTM A1035 steel reinforcing bars}, volume={106}, number={4}, journal={ACI Structural Journal}, author={Seliem, H. M. and Hosny, A. and Rizkalla, S. and Zia, P. and Briggs, M. and Miller, S. and Darwin, D. and Browning, J. and Glass, G. M. and Hoyt, K. and et al.}, year={2009}, pages={530–539} }
 @article{dawood_guddati_rizkalla_2009, title={Effective Splices for a Carbon Fiber-Reinforced Polymer Strengthening System for Steel Bridges and Structures}, ISSN={["0361-1981"]}, DOI={10.3141/2131-12}, abstractNote={Carbon fiber–reinforced polymer (CFRP) materials have been used successfully to strengthen reinforced concrete bridges and structures. Recently, a new high modulus CFRP strengthening system was developed to increase the allowable load carrying capacity and to enhance the serviceability of steel bridges and structures. Because of the relatively high flexural rigidity of the CFRP materials, the length of the CFRP plates that can be transported to the job site is limited. To implement the proposed strengthening system in longer-span steel bridges, adjacent lengths of CFRP must be spliced. To develop an effective splice joint for the proposed strengthening system, an experimental and analytical research program was conducted to study the bond behavior of the CFRP materials. The parameters considered included plate end geometry, splice length, and the possibility of using mechanical anchorage. The analytical study included a finite element analysis to determine the distribution of the stresses within the adhesive layer for different splice configurations. On the basis of the findings, a simplified method was proposed to design lap splice joints with different reversed taper angles and adhesive properties. The research concluded that, with proper detailing, the proposed CFRP system could be effectively used to strengthen steel bridges and structures.}, number={2131}, journal={TRANSPORTATION RESEARCH RECORD}, author={Dawood, Mina and Guddati, Murthy and Rizkalla, Sami}, year={2009}, pages={125–133} }
 @article{rizkalla_hassan_lucier_2009, title={FRP Shear Transfer Mechanism for Precast, Prestressed Concrete Sandwich Load Bearing Panels}, volume={265}, journal={ACI Special Publication}, author={Rizkalla, S. and Hassan, T. and Lucier, G.}, year={2009}, month={Oct}, pages={603–626} }
 @article{mast_dawood_rizkalla_zia_2009, title={Flexural Design of Concrete Beams Reinforced with High Strength Steel Reinforcing Bars}, volume={106}, number={4}, journal={ACI Structural Journal}, author={Mast, R. and Dawood, M. and Rizkalla, S. and Zia, P.}, year={2009}, pages={551–552} }
 @article{rizkalla_zia_mirmiran_russell_mast_2009, title={Proposal for concrete compressive strength up to 18 ksi (124 Mpa) for bridge design}, number={2131}, journal={Transportation Research Record}, author={Rizkalla, S. and Zia, P. and Mirmiran, A. and Russell, H. G. and Mast, R.}, year={2009}, pages={59–67} }
 @article{logan_choi_mirmiran_rizkalla_zia_2009, title={Short-term mechanical properties of high-strength concrete}, volume={106}, number={5}, journal={ACI Materials Journal}, author={Logan, A. and Choi, W. and Mirmiran, A. and Rizkalla, S. and Zia, P.}, year={2009}, pages={413–418} }
 @article{rosenboom_walter_rizkalla_2009, title={Strengthening of prestressed concrete girders with composites: Installation, design and inspection}, volume={23}, ISSN={["1879-0526"]}, DOI={10.1016/j.conbuildmat.2007.11.010}, abstractNote={The application of fibre reinforced polymer (FRP) or steel reinforced polymer (SRP) materials to the tension side of a reinforced/prestressed concrete member has been accepted as a strengthening technique to increase the load carrying capacity and in some cases can enhance member serviceability. Proper installation and regular inspection of a composite (FRP or SRP) strengthening system is important since quality of the bond is essential to internally transfer forces. This paper describes an experimental programme conducted to study the behaviour of six prestressed concrete bridge girders, which were tested under static and fatigue loading conditions. The test results were combined with the results of 16 other girders tested by the authors to develop structural design guidelines and guidelines on the installation and inspection of composite strengthening systems. The behaviour was also examined using value engineering to evaluate the cost-effectiveness by investigating the overall system performance. Research findings indicate that SRP materials are more structurally efficient than carbon FRP (CFRP) materials. The results of an inspection demonstration programme, including the pull-off testing of over 150 CFRP samples, has shown that the most effective inspection techniques are visual inspection, pull-off testing, and acoustic sounding.}, number={4}, journal={CONSTRUCTION AND BUILDING MATERIALS}, author={Rosenboom, Owen and Walter, Catrina and Rizkalla, Sami}, year={2009}, month={Apr}, pages={1495–1507} }
 @article{choi_rizkalla_zia_mirmiran_2008, title={Behavior and design of high-strength prestressed concrete girders}, volume={53}, ISSN={["0887-9672"]}, DOI={10.15554/pcij.09012008.54.69}, abstractNote={This paper proposes provisions to extend the current American Association of State Highway and Transportation Officials' AASHTO LRFD Bridge Design Specifications to include prediction of the ultimate flexural strength of prestressed concrete girders with concrete compressive strengths up to 18 ksi (124 MPa). The proposed design provisions include composite action of a high-strength concrete (HSC) girder with normal-strength Concrete (NSC) deck slab. Nine 40-ft-long (12m) AASHTO Type II HSC girders were tested with and without cast-in-place NSC decks of differing widths to achieve various possible modes of failure. The concrete used for the girder was designed for three target compressive stregths of 10 ksi, 14 ksi, and 18 ksi (69 Mpa, 97 MPa, and 124 Mpa). The experimental program investigated failure modes of three different types of compression zones: one with NSC only, one with HSC only, and one with both NSC and HSC. All girders were tested to failure under static loading to study the different limit-state behaviors, including prestress losses, initiation of cracking, yielding, and final failure mode.}, number={5}, journal={PCI JOURNAL}, author={Choi, Wonchang and Rizkalla, Sami and Zia, Paul and Mirmiran, Amir}, year={2008}, pages={54–69} }
 @article{seliem_lucier_rizkalla_zia_2008, title={Behavior of concrete bridge decks reinforced with high-performance steel}, volume={105}, DOI={10.14359/19071}, abstractNote={This paper describes the behavior of concrete bridge decks reinforced with newly developed high-perfonnance (HPJ steel that is charac­ terized by its high stren gth mId en hanced corrosion-resistance in comparison with conventionaL ASTM A6JS-06 Grade 60 steel. The study presented herein included testing of three full-scale bridge decks with a span-depth ratio of 12.5. The first and second decks were constructed with the same reinforcement ratio using HP and Grade 60 steel, respectively. The third deck was reinforced with HP steel using 33% less reinforcement in an attempt to use its high strength. A nonlinear finite elemen t model was used to predict the mode offailure alldfailure loads. Test results demollstrate that the use of HP steel at a reduced reinforcement ratio is viable as flexural reinforcemellt in concrete bridge decks. The paper also presents the test results of specially-designed specimens to study the effect of bending of HP steel bars on their tensile strength.}, number={1}, journal={ACI Structural Journal}, author={Seliem, H. M. and Lucier, Gregory and Rizkalla, S. H. and Zia, P.}, year={2008}, pages={78–86} }
 @article{mertol_rizkalla_zia_mirmiran_2008, title={Characteristics of compressive stress distribution in high-strength concrete}, volume={105}, number={5}, journal={ACI Structural Journal}, author={Mertol, H. C. and Rizkalla, S. and Zia, P. and Mirmiran, A.}, year={2008}, pages={626–633} }
 @article{rizkalla_dawood_schnerch_2008, title={Development of a carbon fiber reinforced polymer system for strengthening steel structures}, volume={39}, ISSN={1359-835X}, url={http://dx.doi.org/10.1016/j.compositesa.2007.10.009}, DOI={10.1016/j.compositesa.2007.10.009}, abstractNote={This paper summarizes the development and use of high modulus carbon fiber reinforced polymer (HM CFRP) materials for the retrofit of steel structures and bridges. The development work included selection of an appropriate adhesive for bonding HM CFRP materials to steel and the performance of large-scale steel–concrete composite beams tested to examine the behavior using different strengthening schemes. The experimental program investigated the behavior of the strengthening system under fatigue and overloading conditions. A detailed study of bond behavior, including the possible presence of shear-lag effects and performance of spliced joints is also presented. Based on the findings, flexural design guidelines are proposed. The study indicates that CFRP materials can be effectively used to enhance the serviceability and ultimate strength of steel flexural members.}, number={2}, journal={Composites Part A: Applied Science and Manufacturing}, publisher={Elsevier BV}, author={Rizkalla, Sami and Dawood, Mina and Schnerch, David}, year={2008}, month={Feb}, pages={388–397} }
 @article{rosenboom_rizkalla_2008, title={Experimental Study of Intermediate Crack Debonding in Fiber-Reinforced Polymer Strengthened Beams}, volume={105}, DOI={10.14359/19067}, abstractNote={Inteiface crack propagation of fiber-reinforced polymer (FRP)­ strengthened reinforced or prestressed concrete flexural members is often initiated from the toes of the intermediate cracks and propagates toward the supports. This type of FRP delamination is commonly tenned intennediate crack (IC) debonding alld is common for flexural members with high shear span-to-depth ratios. This paper describes an experimental program where six 30ft (9.14 m) lOllg prestressed concrete bridge girders were tested monotonically to fail ure to evalllate the bond characteristics of carbon FRP (CFRP) strengthening systems. Four of the beams Jailed due to Ie debondillg, one failed due to FRP rupture, alld the ul1strengtitened control girderfailed due to concrete crushillg. The results of this study were combined with the results from other tests ill the literature to create a useful experimelllal database. The database was used to assess the analytical models currellliy available in the national code documems. The analysis indicated that the current models do not correlate well with the experimental database and the needfor a new analytical model is highlighted. This paper briefly discusses a proposed model for Ie debonding that predicts the measured values tested by olher researchers well.}, number={1}, journal={ACI Structural Journal}, author={Rosenboom, O. and Rizkalla, S.}, year={2008}, month={Jan}, pages={41–50} }
 @article{mast_dawood_rizkalla_zia_2008, title={Flexural strength design of concrete beams reinforced with high-strength steel bars}, volume={105}, number={5}, journal={ACI Structural Journal}, author={Mast, R. F. and Dawood, M. and Rizkalla, S. H. and Zia, P.}, year={2008}, pages={570–577} }
 @article{schnerch_rizkalla_2008, title={Flexural strengthening of steel bridges with high modulus CFRP strips}, volume={13}, DOI={10.1061/(ASCE)1084-0702(2008)13:2(192)}, abstractNote={Acceptance of carbon fiber-reinforced polymer (CFRP) materials for strengthening concrete structures, together with the recent availability of higher modulus CFRP strips, has resulted in the possibility to also strengthen steel structures. Steel bridge girders and building frames may require strengthening due to corrosion induced cross-section losses or changes in use. An experimental study investigating the feasibility of different strengthening approaches was conducted. Large-scale steel-concrete composite beams, typical of bridge structures, were used to consider the effect of CFRP modulus, prestressing of the CFRP strips, and splicing finite lengths of CFRP strips. All of the techniques examined were effective in utilizing the full capacity of the CFRP material, and increasing the elastic stiffness and ultimate strength of the beams. Results of the experimental program were compared to an analytical model that requires only the beam geometry and the constitutive properties of the CFRP, steel, and concrete. This model was used to investigate the importance of several key parameters. Finally, an approach for design is proposed that considers the bilinear behavior of a typical strengthened beam to the elastic-plastic behavior of the same beam before strengthening.}, number={2}, journal={Journal of Bridge Engineering (ASCE)}, author={Schnerch, D. and Rizkalla, S.}, year={2008}, pages={192–201} }
 @article{reis_rizkalla_2008, title={Material characteristics of 3-D FRP sandwich panels}, volume={22}, ISSN={["0950-0618"]}, DOI={10.1016/j.conbuildmat.2007.03.023}, abstractNote={This paper presents an innovative 3-D fiber reinforced polymer (FRP), panels designed to overcome delamination problems typically encountered in traditional sandwich panels. The sandwich panels consist of GFRP laminates and foam core. The top and bottom consist of GFRP plates connected together with through-thickness fibers to achieve the composite action. The fundamental material characteristics of the panel in tension, compression, flexure and shear are critical for the use and structural design of these panels. This paper summarizes the findings of an extensive experimental program to determine the various parameters believed to affect the material characteristics of these sandwich panels. The influence of the panel thickness, through-thickness fiber configuration and density, and other parameters on the tension, compression, flexure and shear behavior of the panels are discussed.}, number={6}, journal={CONSTRUCTION AND BUILDING MATERIALS}, author={Reis, Engin M. and Rizkalla, Sami H.}, year={2008}, month={Jun}, pages={1009–1018} }
 @article{rosenboom_rizkalla_2008, title={Modeling of IC debonding of FRP-strengthened concrete flexural members}, volume={12}, DOI={10.1061/(ASCE)1090-0268(2008)12:2(168)}, abstractNote={The presence of a fiber-reinforced polymer (FRP) strengthening material bonded to the tension face of a reinforced concrete beam will restrict but not prevent the opening of intermediate flexural cracks due to applied loading. Test results indicate that displacements at the toe of flexural cracks create stress concentrations at the interface of the FRP laminate and the beam, leading to the development of localized interface cracks that, typically, propagate, under the effect of the load, to join the original flexural cracks and cause delamination of the FRP system. This type of FRP delamination is commonly termed intermediate crack (IC) debonding. In this paper the analytical models published in the literature are reviewed and it was found that these models do not correlate well with measured experimental results. This paper proposes an analytical model that characterizes the interface shear stress based on two distinct sources: (1) the change in the applied moments along the length of the member and (2) ...}, number={2}, journal={Journal of Composites for Construction}, author={Rosenboom, O. and Rizkalla, S.}, year={2008}, pages={168–179} }
 @article{hassan_vickery_rizkalla_2008, title={Properties of adhesives and CPVC materials proposed for steel tank lining}, volume={28}, ISSN={["0143-7496"]}, DOI={10.1016/j.ijadhadh.2007.05.002}, abstractNote={This paper focuses on the behavior of structural adhesives used in tank lining applications. The experimental program addresses the fundamental material properties and bond characteristics of adhesives when subjected to normal and severe environmental conditions. A total of 132 adhesive and CPVC tension coupons were examined under severe environmental exposure to determine the influence of these conditions on the tensile strength. Double-lap shear tests were conducted to evaluate the shear strength of the adhesive using 50 CPVC-to-steel specimens. The overall composite behavior of the proposed lining for steel tanks was investigated using three small-scale test specimens to simulate the conditions of a typical tank lining. The specimens were subjected to extreme temperature changes to examine the thermal gradient distribution and the composite interaction of the CPVC liner to the steel wall. Research findings provide better understanding of the performance of adhesives when subjected to severe environmental conditions and different sustained load levels.}, number={1-2}, journal={INTERNATIONAL JOURNAL OF ADHESION AND ADHESIVES}, author={Hassan, Tarek K. and Vickery, John D. and Rizkalla, Sami H.}, year={2008}, pages={77–90} }
 @article{hassan_seliem_dwairi_rizkalla_zia_2008, title={Shear behavior of large concrete beams reinforced with high-strength steel}, volume={105}, number={2}, journal={ACI Structural Journal}, author={Hassan, T. K. and Seliem, H. M. and Dwairi, H. and Rizkalla, S. H. and Zia, P.}, year={2008}, pages={173–179} }
 @article{johnson_mohamed_rizkalla_2007, title={Behavior of Three-Dimensionally Woven Glass Fiber Reinforced Polymeric Bridge Deck}, volume={1}, number={2}, journal={Composites Research Journal}, author={Johnson, C. and Mohamed, T. and Rizkalla, S.}, year={2007}, pages={27–42} }
 @article{dawood_rizkalla_gleich_2007, title={CFRP Materials for Reinforced Concrete Structures}, volume={52}, number={5}, journal={PCI Journal}, author={Dawood, M. and Rizkalla, S. and Gleich, H.}, year={2007}, month={Sep}, pages={27–29} }
 @article{mertol_rizkalla_scott_lees_el-hacha_2007, title={Durability of Concrete Beams Prestressed with CFRP Tendons}, volume={S245}, journal={ACI Special Publication, Case Histories and Use of FRP for Prestressing Applications}, author={Mertol, H. and Rizkalla, S. and Scott, P. and Lees, J. and El-Hacha, R.}, year={2007}, month={Oct}, pages={1–20} }
 @article{dawood_rizkalla_sumner_2007, title={Fatigue and overloading Behavior of steel-concrete composite flexural members strengthened with high modulus CFRP materials}, volume={11}, DOI={10.1061/(ASCE)1090-0268(2007)11:6(659)}, abstractNote={Due to corrosion and the continuous demand to increase traffic loads, there is a need for an effective system which can be used to repair and/or strengthen steel bridges and structures. This paper describes an experimental program, recently completed, to investigate the fundamental behavior of steel–concrete composite scaled bridge beams strengthened with new high modulus carbon fiber-reinforced polymer (HM CFRP) materials. The behavior of the beams under overloading conditions and fatigue loading conditions was studied as well as the possible presence of shear lag at the interface of the steel surface and the CFRP strengthening material. The test results are compared to an analytical model based on the fundamental principles of equilibrium and compatibility, to predict the behavior of the strengthened steel–concrete composite beams. Based on the findings of this research work, combined with other work in the literature, a design guideline is proposed for the use of HM CFRP for strengthening the steel fle...}, number={6}, journal={Journal of Composites for Construction}, author={Dawood, M. and Rizkalla, S. and Sumner, E.}, year={2007}, pages={659–669} }
 @article{mertol_rizkalla_zia_mirmiran_2007, title={Flexural Design of High Strength Concrete Members}, volume={104}, number={4}, journal={ACI Structural Journal}, author={Mertol, H.C. and Rizkalla, S. and Zia, P. and Mirmiran, A.}, year={2007}, month={Apr} }
 @article{rosenboom_hassan_rizkalla_2007, title={Flexural behavior of aged prestressed concrete girders strengthened with various FRP systems}, volume={21}, ISSN={0950-0618}, url={http://dx.doi.org/10.1016/j.conbuildmat.2006.06.007}, DOI={10.1016/j.conbuildmat.2006.06.007}, abstractNote={Many prestressed concrete bridges are in need of upgrading in order to increase their posted capacities. Departments of transportation across the country have been faced with large financial burdens on the maintenance budget, negative psychological effects on highway users, long traffic delays during maintenance, potential safety hazards, and reduced service life as a result of the deficiencies. In response to considerable consultation with the North Carolina Department of Transportation (NCDOT), a research project with practical goals was initiated to evaluate the cost-effectiveness and value engineering of Carbon Fiber Reinforced Polymer (CFRP) repair and strengthening systems for prestressed concrete bridge girders. This paper presents the first phase of the research program, involving the testing under static loading conditions of eight prestressed concrete bridge girders, six strengthened with various CFRP systems. Results show that the ultimate capacity of prestressed concrete bridge girders can be increased by as much as 73% using CFRP without sacrificing the ductility of the original member. Transverse CFRP U-wrap reinforcements are recommended along the length of the girder to control debonding type failures. The second phase of the research will examine the fatigue behavior of the strengthened girders, and provide analysis under service loading conditions.}, number={4}, journal={Construction and Building Materials}, publisher={Elsevier BV}, author={Rosenboom, Owen and Hassan, Tare K. and Rizkalla, Sami}, year={2007}, month={Apr}, pages={764–776} }
 @misc{dawood_rizkalla_gleich_2007, title={Galvanic corrosion rare with proper detailing}, volume={52}, number={5}, journal={PCI Journal}, author={Dawood, M. and Rizkalla, S. and Gleich, H.}, year={2007}, pages={27–29} }
 @article{fam_rizkalla_2007, title={Laboratory simulation of impact loading on laminated glass for ice hockey arenas}, volume={31}, ISSN={["0732-8818"]}, DOI={10.1111/j.1747-1567.2007.00181.x}, abstractNote={Laminated tempered glass sheets were tested under impact loading to simulate conditions in ice hockey arenas, where pucks hit the glass shields at high velocities. Thirty-six tests have been conducted on 1220x460mm sheets of glass, 9.5, 12.7 and 15.9 mm thick, using falling weights attached to an actual puck. Twenty-four of the specimens were laminated on one side using 0.36 mm thick polyester transparent laminates. The weights and drop heights were increased gradually until failure occurred. The kinetic energy, equivalent puck field velocities, equivalent static failure loads and stresses have been estimated. The estimated field velocities of the pucks at failure were all higher than the maximum recorded in the game. The study showed that lamination has significantly changed failure mode of glass from a catastrophic failure, where fragments shatter, potentially causing serious injuries, to one which is still brittle yet substantially safer as fractured glass remains fully intact. No rupture or delamination of the laminates was observed.}, number={5}, journal={EXPERIMENTAL TECHNIQUES}, author={Fam, A. and Rizkalla, S.}, year={2007}, pages={46–52} }
 @article{hassan_lucier_rizkalla_zia_2007, title={Modeling of L-shaped, precast, prestressed concrete spandrels}, volume={52}, ISSN={["0887-9672"]}, DOI={10.15554/pcij.03012007.78.92}, abstractNote={This paper presents results of nonlinear finite element (FE) analyses conducted to model the behavior of L-shaped, precast, prestressed concrete spandrels built with open web reinforcement. The FE model was calibrated using experimental results from recent tests of slender, L-shaped, precast, prestressed concrete spandrels. Detailed correlative studies between analytical and experimental results are provided, demonstrating the capability of the FE program to describe the observed experimental behavior. The feasibility of using open web reinforcement in compact, L-shaped, precast, prestressed concrete spandrels to achieve a more construction-friendly reinforcement scheme is also examined. Five different web reinforcement configurations for the compact spandrels were studied in order to evaluate the contribution of closed stirrups to the spandrels' shear-torsion behavior. The behavior, ultimate load-carrying capacity, and mode of failure of both the slender and compact L-shaped precast, prestressed concrete spandrels are presented. For loading values near the ultimate, the out-of-plane bending behavior of compact, L-shaped, precast, prestressed concrete spandrels is strongly influenced by the web-reinforcement configuration. Results from the analysis show that for long-span, compact spandrels, open web reinforcement can be used effectively to resist torsional forces throughout the member.}, number={2}, journal={PCI JOURNAL}, author={Hassan, Tarek and Lucier, Gregory and Rizkalla, Sarni and Zia, Paul}, year={2007}, pages={78–92} }
 @article{lucier_rizkalla_zia_klein_2007, title={Precast Concrete, L-Shaped Spandrels Revisited: Full-Scale Tests}, volume={52}, ISSN={0887-9672}, url={http://dx.doi.org/10.15554/pcij.03012007.62.76}, DOI={10.15554/pcij.03012007.62.76}, abstractNote={This paper presents results from full-scale testing conducted on 4 precast, prestressed concrete L-shaped spandrels. The 4 L-shaped spandrels were each loaded through 12-ft-long, prestressed double tees that rested on the spandrel ledge at one end and on an independent support at the other. None of the beams were constructed with closed stirrups of mild-steel reinforcement. Rather, different arrangements of transverse L-shaped bars, welded-wire reinforcement, and longitudinal bars were provided to resist the shear and torsion induced in the spandrels. Shear and torsion forces were created by the double-tee reaction forces that were loaded eccentrically to the spandrels. The transverse and longitudinal reinforcement resisted the combined effects of vertical shear and out-of-plane bending of the web and satisfied minimum vertical hanger reinforcement requirements for ledge-to-web attachment. All beams sustained loads in excess of their factored design loads. Eliminating the need for closed reinforcement in slender spandrels would be of significant benefit to the precast concrete industry. This design approach would enhance constructability of slender members, which could increase plant productivity and reduce overall costs. Behavior of all 4 spandrels at various limit states is presented, including crack patterns and failure modes. Researchers used these test results to better understand the fundamental mechanism developed in the L-shaped spandrels to resist shear and torsion.}, number={2}, journal={PCI Journal}, publisher={Precast/Prestressed Concrete Institute}, author={Lucier, Gregory and Rizkalla, Sami and Zia, Paul and Klein, Gary}, year={2007}, month={Mar}, pages={62–76} }
 @article{schnerch_dawood_rizkalla_sumner_2007, title={Proposed design guidelines for strengthening of steel bridges with FRP materials}, volume={21}, ISSN={["1879-0526"]}, DOI={10.1016/j.conbuildmat.2006.03.003}, abstractNote={This paper focuses on the use of externally bonded high modulus carbon fiber reinforced polymer (HM CFRP) materials to strengthen steel bridges and structures. Proper installation of the CFRP materials is necessary to prevent premature failure due to debonding. The paper proposes guidelines and installation techniques based on the best practice reported in the literature and the extensive practical experience in bonding of composite materials. The surface preparation of the materials, the application of the adhesive and the detailing of the strengthening are provided in detail. The design guidelines include the structural design criteria for the use of high modulus CFRP materials as flexural strengthening system of typical steel–concrete composite bridge girders. The flexural design procedure is based on a moment–curvature analysis and a specified increase of the live load carried by the bridge to satisfy specific serviceability requirements. A bond model is also described which can be used to calculate the shear and peel stresses within the adhesive thickness. To prevent a premature debonding failure of the strengthening system, the criteria specify a maximum principle stress in the adhesive which cannot be exceeded for a given characteristic strength of an adhesive. A worked example is presented to illustrate the proposed flexural design approach. The research findings conclude that high modulus CFRP materials provide a promising alternative for strengthening steel bridges that can be easily designed and installed to increase their strength and stiffness.}, number={5}, journal={CONSTRUCTION AND BUILDING MATERIALS}, author={Schnerch, D. and Dawood, M. and Rizkalla, S. and Sumner, E.}, year={2007}, month={May}, pages={1001–1010} }
 @misc{lucier_hassan_rizkalla_klein_zia_2007, title={Stirrups for torsion resistance prompt questions - Authors' response}, volume={52}, number={4}, journal={PCI Journal}, author={Lucier, G. and Hassan, T. and Rizkalla, S. and Klein, G. and Zia, P.}, year={2007}, pages={14–14} }
 @article{fawzia_al-mahaidi_zhao_rizkalla_2007, title={Strengthening of circular hollow steel tubular sections using high modulus CFRP sheets}, volume={21}, ISSN={["1879-0526"]}, DOI={10.1016/j.conbuildmat.2006.06.014}, abstractNote={This paper describes the behaviour of very high strength (VHS) circular steel tubes strengthened by carbon fibre reinforced polymer (CFRP) and subjected to axial tension. A series of tests were conducted with different bond lengths and number of layers. The distribution of strain through the thickness of CFRP layers and along the CFRP bond length was studied. The strain was found to generally decrease along the CFRP bond length far from the joint. The strain through the thickness of the CFRP layers was also found to decrease from the bottom to top layer. The effective bond length for high modulus CFRP was established. Finally empirical models were developed to estimate the maximum load for a given CFRP arrangement.}, number={4}, journal={CONSTRUCTION AND BUILDING MATERIALS}, author={Fawzia, S. and Al-Mahaidi, R. and Zhao, X. L. and Rizkalla, S.}, year={2007}, month={Apr}, pages={839–845} }
 @article{rosenboom_rizkalla_2006, title={Behavior of prestressed concrete strengthened with various CFRP systems subjected to fatigue loading}, volume={10}, DOI={10.1061/(ASCE)1090-0268(2006)10:6(492)}, abstractNote={Many prestressed concrete bridges are in need of upgrades to increase their posted capacities. The use of carbon fiber-reinforced polymer (CFRP) materials is gaining credibility as a strengthening option for reinforced concrete, yet few studies have been undertaken to determine their effectiveness for strengthening prestressed concrete. The effect of the CFRP strengthening on the induced fatigue stress ratio in the prestressing strand during service loading conditions is not well defined. This paper explores the fatigue behavior of prestressed concrete bridge girders strengthened with CFRP through examining the behavior of seven decommissioned 9.14 m (30 ft) girders strengthened with various CFRP systems including near-surface-mounted bars and strips, and externally bonded strips and sheets. Various levels of strengthening, prestressing configurations, and fatigue loading range are examined. The experimental results are used to provide recommendations on the effectiveness of each strengthening configurati...}, number={6}, journal={Journal of Composites for Construction}, author={Rosenboom, O. and Rizkalla, S.}, year={2006}, pages={492–502} }
 @article{schnerch_dawood_rizkalla_sumner_stanford_2006, title={Bond behavior of CFRP strengthened steel structures}, volume={9}, ISSN={["1369-4332"]}, DOI={10.1260/136943306779369464}, abstractNote={Recent research has focused on rehabilitation and strengthening of steel structures and bridges using fiber reinforced polymer (FRP) materials. The bond behavior of FRP materials to steel structures is quite different from that of concrete structures. Preliminary test results showed the occurrence of very high bond stresses for most strengthening applications due to the amount of strengthening required for steel structures and bridges. In this paper, surface preparation methods and means of preventing galvanic corrosion are discussed. The results of an experimental program for selection of suitable adhesives through determination of the development length is discussed as well as preliminary testing showing the importance of proper detailing of the ends of the FRP strips. The shear stress distribution determined in the experimental program is compared to analytical models using a stress-based approach. The remainder of the paper focuses on the current methods for determining bond stresses and their use for the design of FRP strengthening system for steel structures.}, number={6}, journal={ADVANCES IN STRUCTURAL ENGINEERING}, author={Schnerch, D. and Dawood, M. and Rizkalla, S. and Sumner, E. and Stanford, K.}, year={2006}, month={Dec}, pages={805–817} }
 @article{el-hacha_el-agroudy_rizkalla_2006, title={Bond characteristics of high-strength steel reinforcement}, volume={103}, DOI={10.14359/18227}, abstractNote={This paper summarizes an investigation undertaken to study the bond characteristics of high-strength steel reinforcement bars commercially known as microcomposite, multistructural, formable steel (MMFX). The objective of the investigation is to examine the applicability of the ACT 318-02 equation and a current proposed equation by Zuo and Darwin on bond behavior of steel reinforcement to the concrete member. The experimental program included two phases. The first phase of the experimental program consisted of testing four beam-end specimens reinforced with MMFX steel bars, whereas the second phase included testing eight beam-splice specimens reinforced with MMFX steel bars. The selected four factors considered in this study were bar size, level of confinement, bonded length, and bar cast position. The bond behavior of the MMFX steel bars was found to be similar to that of conventional Grade 420 MPa (60 ksi) steel up to the proportional limit of 550 MPa (80 ksi). The bond strength of the MMFX significantly changes as the tensile stresses developed in the bar exceed the proportional limit. The test results indicated that both the AC! 318-02 equation and the current proposed equation by Zuo and Darwin on bond are adequate and resulted in conservative prediction at low stress levels up to 550 MPa (80 ksi). At high stress levels, however, the prediction using both equations is unconservative due to the nonlinear behavior of the MMFX stress-strain relationship. Based on the limited number of specimens considered in this study, modification to both the AC1 318-02 equation and the Zuo and Darwin equation is proposed to predict the bond forces beyond the proportional limit for MMFX steel bars.}, number={6}, journal={ACI Structural Journal}, author={El-Hacha, R. and El-Agroudy, H. and Rizkalla, S. H.}, year={2006}, pages={771–782} }
 @inbook{dawood_sumner_rizkalla_2006, place={Dordrecht}, series={Solid Mechanics and Its Applications}, title={Fundamental Characteristics of New High Modulus CFRP Materials for Strengthening Steel Bridges and Structures}, ISBN={9781402048906}, url={http://dx.doi.org/10.1007/1-4020-4891-2_18}, DOI={10.1007/1-4020-4891-2_18}, booktitle={Advances in Engineering Structures, Mechanics & Construction}, publisher={Springer Netherlands}, author={Dawood, Mina and Sumner, Emmett and Rizkalla, Sami}, editor={Pandey, M. and Xie, W.C. and Xu, L.Editors}, year={2006}, month={Feb}, pages={215–226}, collection={Solid Mechanics and Its Applications} }
 @article{fam_witt_rizkalla_2006, title={Repair of damaged aluminum truss joints of highway overhead sign structures using FRP}, volume={20}, ISSN={["0950-0618"]}, DOI={10.1016/j.conbuildmat.2005.06.014}, abstractNote={An innovative repair technique is introduced for aluminum truss-type highway overhead sign structures, using fibre-reinforced polymer (FRP) sheets. The welded k-joints are typically subjected to excessive fatigue-induced cracking under the effects of wind and moving traffic. The repair technique proposed in this paper utilizes longitudinal FRP layers bonded to the diagonals and wrapped around the main chord to form alternating v-patterns, followed by additional circumferential layers for anchorage. Eight tests were conducted on four full-scale specimens. Weld lines at the junction between diagonals and main chord were ground to simulate a 90% loss of joint strength. After repair, diagonals were loaded to failure in tension. The study showed that full strength of the welded joints was restored using carbon-FRP sheets. Only 70% of joint strength was restored when using glass-FRP. The strengthening technique is particularly sensitive to quality control during installation. A field application using the proposed technique was successfully completed by the New York State Department of Transportation for a cracked aluminum truss over Route 88 in NY State.}, number={10}, journal={CONSTRUCTION AND BUILDING MATERIALS}, author={Fam, Amir and Witt, Sarah and Rizkalla, Sami}, year={2006}, month={Dec}, pages={948–956} }
 @article{fam_rizkalla_2006, title={Structural performance of laminated and unlaminated tempered glass under monotonic transverse loading}, volume={20}, ISSN={["0950-0618"]}, DOI={10.1016/j.conbuildmat.2005.01.051}, abstractNote={A total of thirty six bending tests have been conducted on 1220 × 460 mm sheets of glass, 9.5-, 12.7- and 15.9-mm thick, using slow-rate monotonic loading. Twenty four specimens were laminated on one side using either one or two 0.36-mm thick polyester transparent laminates. The study showed that lamination has significantly changed the failure mode of glass from a catastrophic failure, where fragments of glass shatter in different directions, to one which is still brittle yet safer, as the fractured glass remains fully intact. The average gains in flexural strength, stiffness and strain energy, as a result of lamination, were 20%, 10% and 34%, respectively, while the maximum gains in flexural strength, stiffness and strain energy were 36%, 33% and 52%, respectively. Because of the scatter of data, no specific correlation between the gains and reinforcement ratio (expressed as the ratio of laminate-to-glass thickness) could be established. The load–deflection behaviour of both laminated and unlaminated glass was linear up to failure. No rupture or delamination of the laminates were observed}, number={9}, journal={CONSTRUCTION AND BUILDING MATERIALS}, author={Fam, Amir and Rizkalla, Sami}, year={2006}, month={Nov}, pages={761–768} }
 @article{fawzia_zhao_al-mahaidi_rizkalla_2005, title={Bond Characteristics between CFRP and steel plates in double strap joints}, volume={1}, number={2}, journal={Advanced Steel Construction}, author={Fawzia, S. and Zhao, X.L. and Al-Mahaidi, R. and Rizkalla, S.}, year={2005}, pages={17–27} }
 @article{el-hacha_rizkalla_kotynia_2005, title={Modelling of Reinforced Concrete Flexural Members Strengthened with Near-Surface Mounted FRP Reinforcement}, volume={230}, journal={ACI Special Publication}, author={El-Hacha, R. and Rizkalla, S. and Kotynia, R.}, year={2005}, month={Nov}, pages={1681–1700} }
 @article{fam_manda_rizkalla_2005, title={Rectangular filament-wound glass fiber reinforced polymer tubes filled with concrete under flexural and axial loading: Analytical modeling}, volume={9}, DOI={10.1061/(ASCE)1090-0268(2005)9:1(34)}, abstractNote={This paper presents an analytical model to predict the behavior of concrete-filled rectangular fiber reinforced polymer (FRP) tubes (CFRFTs), subjected to bending and axial loads. The model accounts for different laminate structures of the flange and web of the tube. Gradual reduction of stiffness, resulting from progressive failure of FRP layers oriented at various angles is considered through the ultimate laminate failure approach. The model adopts cracked section analysis, using layer-by-layer approach and accounts for totally and partially filled tubes. The model predicts the moment–curvature responses of beams, load–strain responses of columns, and complete interaction curves of beam–columns. The model is verified using experimental results and is used to study the effects of laminate structure, hybrid laminates, thickness of the tube and optimization of partially filled tubes. Comparisons of CFRFT with conventional reinforced concrete (RC) sections showed that CFRFT could provide axial load–bending ...}, number={1}, journal={Journal of Composites for Construction}, author={Fam, A. and Manda, S. and Rizkalla, S.}, year={2005}, pages={34–43} }
 @article{fam_schnerch_rizkalla_2005, title={Rectangular filament-wound glass fiber reinforced polymer tubes filled with concrete under flexural and axial loading: Experimental investigation}, volume={9}, DOI={10.1061/(ASCE)1090-0268(2005)9:1(25)}, abstractNote={This paper presents results of an experimental investigation on three beams and five short columns, consisting of glass fiber reinforced polymer concrete-filled rectangular filament-wound tubes (CFRFTs). The tubes included fibers oriented at 45 deg and 90 deg with respect to the longitudinal axis. Additional longitudinal fibers [0 deg] were provided in flanges for flexural rigidity. Beams included totally filled tubes and a tube partially filled with concrete, which had a central hole for reducing deadweight. The effect of reinforcement ratio was examined by using tubes of two different sizes. Flexural behavior of CFRFT was compared to concrete-filled rectangular steel tubes (CFRSTs) of similar reinforcement ratios. Short columns were tested under eccentricity ratios (e/h) of 0, 0.09, 0.18, and 0.24, where h is the section depth. Transverse strains were measured around the perimeter of concentrically loaded column to evaluate confinement effect. The study showed that CFRFT is a feasible system that could offer similar flexural strength to CFRST. The tube laminate structure and its progressive failure contribute to the slightly nonlinear behavior of beams. The CFRFT beam with inner hole had an overall strength-to-weight ratio, 77% higher than the totally filled beam, but failed in compression. Bulging of CFRFT columns has limited their confinement effectiveness.}, number={1}, journal={Journal of Composites for Construction}, author={Fam, A. and Schnerch, D. and Rizkalla, S.}, year={2005}, pages={25–33} }
 @article{hassan_rizkalla_2004, title={Bond mechanism of near-surface-mounted fiber-reinforced polymer bars for flexural strengthening of concrete structures}, volume={101}, DOI={10.14359/13458}, abstractNote={This paper presents both experimental and analytical investigations undertaken to evaluate bond characteristics of near-sutfacemounted (NSM) carbon fiber-reinforced polymer (CFRP) bars. A total of eight concrete beams. strengthened with NSM CFRP bars, were tested under monotonic static loading. Different embedment lengths are studied to determine the development length of the fiber-reinforced polymer (FRP) reinforcement. The performance of two different adhesives used to bond the bars to the surrounding concrete is examined. A general methodology to evaluate the development length of NSM FRP bars of different configurations and types of fibers is presented. A quantitative criterion governing debonding failure is established. The proposed bond model assumes linear elastic behavior jar the concrete, adhesive, and the NSM FRP bars, following the same philosophy oj the ACI provisions for bond analysis and design. The proposed analytical model is validated by comparing the predicted values with test results as well as to nonlinear finite element modelling. The influence of key parameters, including the thickness of the adhesive cover, groove width, groove spacing, and inte171ai steel reinforcement configuration, are discussed.}, number={6}, journal={ACI Structural Journal}, author={Hassan, T. K. and Rizkalla, S. H.}, year={2004}, pages={830–839} }
 @article{fam_qie_rizkalla_2004, title={Concrete-filled steel tubes subjected to axial compression and lateral cyclic loads}, volume={130}, DOI={10.1061/(asce)0733-9445(2004)130:4(631)}, abstractNote={This paper presents an experimental work and analytical modeling for concrete-filled steel tubes (CFSTs) subjected to concentric axial compression and combined axial compression and lateral cyclic loading. The objective of the study is to evaluate the strength and ductility of CFST short columns and beam-column members under different bond and end loading conditions. Both bonded and unbonded specimens were tested, including application of the axial load to the composite steel-concrete section and to the concrete core only. Research findings indicate that the bond and end loading conditions did not affect the flexural strength of beam-column members significantly. On the other hand, the axial strengths of the unbonded short columns were slightly increased, compared to those of the bonded ones, while the stiffness of the unbonded specimens was slightly reduced. Test results were compared with the available design specifications, which were found to be conservative. The paper also presents an analytical model capable of predicting the flexural and axial load strength of CFST members. Experimental results were found to be in good agreement with the predicted values.}, number={4}, journal={Journal of Structural Engineering (New York, N.Y.)}, author={Fam, A. and Qie, F. S. and Rizkalla, S.}, year={2004}, pages={631–640} }
 @article{el-hacha_rizkalla_2004, title={Near-surface-mounted fiber-reinforced polymer reinforcements for flexural strengthening of concrete structures}, volume={101}, DOI={10.14359/13394}, abstractNote={Use of fiber-reinforced polymer (FRP) materials to strengthen bridges has been adopted extensively in the last decade. FRP has been used in different configurations and techniques to use the material effectively and to ensure long service life of the selected system. One of these innovative strengthening techniques is near-surface mounting (NSM) that consists of placing FRP reinforcing bars or strips into grooves precut into the concrete cover in the tension region of the strengthened concrete member. This method is relatively simple and considerably enhances the bond of the mounted FRP reinforcements, thereby using the material more effectively. This paper presents test results of reinforced concrete (RC) T-beams strengthened in flexure with different strengthening systems using FRP reinforcing bars and strips as NSM reinforcement and externally bonded FRP strips. The FRP reinforcements used in this investigation include carbon FRP (CFRP) reinforcing bars and strips and glass FRP (GFRP) thermoplastic strips. Behavior and effectiveness of the materials used for the various strengthening systems are compared. The structural performance and modes of failure of the tested beams are presented and discussed. Test results indicated that using NSM FRP reinforcing bars and strips is practical, significantly improves the stiffness, and increases the flexural capacity of RC beams. The limitations of using NSM FRP reinforcing bars and strips are controlled by serviceability requirements in terms of overall deflections and crack widths rather than delamination, observed by many researchers, of externally bonded FRP reinforcement. Strengthening of RC beams using NSM FRP strips provided higher strength capacity than externally bonded FRP strips using the same material with the same axial stiffness.}, number={5}, journal={ACI Structural Journal}, author={El-Hacha, R. and Rizkalla, S. H.}, year={2004}, pages={717–726} }
 @article{schnerch_stanford_sumner_rizkalla_2004, title={Strengthening steel structures and bridges with high-modulus carbon fiber-reinforced polymers - Resin selection and scaled monopole behavior}, ISBN={["0-309-09487-9"]}, ISSN={["0361-1981"]}, DOI={10.3141/1892-25}, abstractNote={Cost-effective solutions for the rehabilitation and strengthening of steel structures, including bridges and monopole towers, are greatly needed. Rehabilitation is often required because of cross-section losses occurring as a result of corrosion; strengthening may also be required because of changes in the use of a structure. Current techniques for strengthening steel structures have several drawbacks, including their fatigue performance and the need for ongoing maintenance owing to continued corrosion attack. The current research program makes use of a high-modulus carbon fiber for the strengthening of steel structures. This program, currently in progress, includes phases for the resin and adhesive selection for wet layup of carbon fiber sheets and bonding of precured laminate plates. Test results of the first scaled monopole tower showed a 25% increase in stiffness in the elastic range compared with the same monopole before strengthening.}, number={1892}, journal={DESIGN OF STRUCTURES 2004}, author={Schnerch, D and Stanford, K and Sumner, EA and Rizkalla, S}, year={2004}, pages={237–245} }
 @article{becque_patnaik_rizkalla_2003, title={Analytical models for concrete confined with FRP tubes}, volume={7}, DOI={10.1061/(ASCE)1090-0268(2003)7:1(31)}, abstractNote={Concrete columns encased in fiber-reinforced polymer (FRP) tubes offer an attractive solution to enhance behavior of concrete in terms of strength as well as ductility. Analytical models for development of stress-strain curves for concrete confined with FRP are proposed in this paper. The predicted stress-strain curves for confined concrete using the proposed models are compared with those of tests for concrete specimens confined with FRP. It is demonstrated that the proposed models predict the stress-strain behavior of confined concrete very well. Based on the confidence gained in the proposed models, the effects of using different fibers, the presence of voids, and the number of layers are established.}, number={1}, journal={Journal of Composites for Construction}, author={Becque, J. and Patnaik, A. K. and Rizkalla, S. H.}, year={2003}, pages={31–38} }
 @article{svecova_rizkalla_tadros_2003, title={Design of FRP Reinforced Concrete for Serviceability}, volume={210}, number={SP-210}, journal={ACI Special Publications}, author={Svecova, D. and Rizkalla, S. and Tadros, G.}, year={2003}, pages={149–173} }
 @article{rizkalla_hassan_hassan_2003, title={Design recommendations for the use of FRP for reinforcement and strengthening of concrete structures}, volume={5}, ISSN={1365-0556 1528-2716}, url={http://dx.doi.org/10.1002/pse.139}, DOI={10.1002/pse.139}, abstractNote={The use of fibre reinforced polymer, FRP, as reinforcement for concrete structures has been growing rapidly in recent years. This paper summarizes the current state of knowledge of these materials and highlights the various FRP strengthening techniques that have been used for concrete and masonry structures. Material characteristics of FRP and fundamental design considerations are discussed. Selection of the appropriate materials and their corresponding advantages and disadvantages are highlighted. Design philosophies for concrete members reinforced and/or strengthened with FRP are enumerated. Fundamental flexure, shear and bond behaviour of concrete members reinforced and/or strengthened with FRP according to the current ACI design guidelines are examined. The paper also reviews the durability aspects of FRP and describes selected field applications of these materials. Copyright © 2003 John Wiley & Sons, Ltd.}, number={1}, journal={Progress in Structural Engineering and Materials}, publisher={Wiley}, author={Rizkalla, Sami and Hassan, Tarek and Hassan, Nahla}, year={2003}, month={Jan}, pages={16–28} }
 @article{fam_flisak_rizkalla_2003, title={Experimental and analytical modeling of concrete-filled fiber- reinforced polymer tubes subjected to combined bending and axial loads}, volume={100}, DOI={10.14359/12659}, abstractNote={This paper presents test results of an experimental program, and proposes an analytical model to describe the behavior of concrete-filled, fiber-reinforced polymer (FRP) tubes subjected to combined axial compression loads and bending moments. The experimental program included 10 specimens subjected to eccentric axial loads, 2 specimens tested under concentric axial loads, and 2 specimens tested in bending. Glass FRP tubes with 2 different laminate structures were considered, and axial load/bending moment interaction curves are given. An analytical model is presented that accounts for variable confinement of concrete as a result of the gradual change of the biaxial state of stresses developed in the tube as the eccentricity changes. A parametric study was conducted to evaluate effects of diameter-to-thickness ratio and laminate structure of the tube, including different fiber proportions in the axial and hoop directions. The study evaluated the confinement as affected by the eccentricity of the applied axial load as well as the influence of the FRP laminate structure. Findings indicate that the interaction curves are significantly affected by both the laminate structure and diameter-to-thickness ratios of the tubes.}, number={4}, journal={ACI Structural Journal}, author={Fam, A. and Flisak, B. and Rizkalla, S.}, year={2003}, pages={499–509} }
 @article{demers_popovic_neale_rizkalla_tadros_2003, title={FRP Retrofit of the Ring-Beam of a Nuclear Reactor Containment Structure}, volume={SP-215}, journal={ACI Special Publications}, author={Demers, M. and Popovic, A. and Neale, K. and Rizkalla, S. and Tadros, G.}, year={2003}, month={Nov}, pages={303–316} }
 @article{rizkalla_tadros_2003, title={FRP for Prestressing of Concrete Bridges in Canada}, volume={215}, journal={ACI Special Publications}, author={Rizkalla, S. and Tadros, G.}, year={2003}, month={Nov}, pages={75–90} }
 @article{fam_greene_rizkalla_2003, title={Field Applications of Concrete-Filled FRP Tubes for Marine Piles}, volume={SP-215}, journal={ACI Special Publications}, publisher={ACI Special Publications}, author={Fam, A. and Greene, R. and Rizkalla, S.}, year={2003}, month={Nov}, pages={161–180} }
 @article{williams_shehata_rizkalla_2003, title={Filament-wound glass fiber reinforced polymer bridge deck modules}, volume={7}, DOI={10.1061/(ASCE)1090-0268(2003)7:3(266)}, abstractNote={The demand for the development of efficient and durable bridge decks is a priority for most of the highway authorities worldwide. This paper summarizes the results of an experimental program designed to study the behavior of an innovative glass fiber reinforced polymer (GFRP) bridge deck recently patented in Canada. The deck consisted of a number of triangular filament wound tubes bonded with epoxy resin. GFRP plates were adhered to the top and bottom of the tubes to create one modular unit. The experimental program, described in this paper, discusses the evolution of two generations of the bridge deck. In the first generation, three prototype specimens were tested to failure, and their performance was analyzed. Based on the behavior observed, a second generation of bridge decks was fabricated and tested. The performance was evaluated based on load capacity, mode of failure, deflection at service load level, and strain behavior. All decks tested exceeded the requirements to support HS30 design truck loads specified by AASHTO with a margin of safety. This paper also presents an analytical model, based on Classical Laminate Theory to predict the load-deflection behavior of the FRP decks up to service load level. In all cases the model predicted the deck behavior very well.}, number={3}, journal={Journal of Composites for Construction}, author={Williams, B. and Shehata, E. and Rizkalla, S. H.}, year={2003}, pages={266–273} }
 @article{hassan_rizkalla_2003, title={Investigation of bond in concrete structures strengthened with near surface mounted carbon fiber reinforced polymer strips}, volume={7}, DOI={10.1061/(ASCE)1090-0268(2003)7:3(248)}, abstractNote={Fiber reinforced polymer (FRP) materials are currently produced in different configurations and are widely used for the strengthening and retrofitting of concrete structures and bridges. Recently, considerable research has been directed to characterize the use of FRP bars and strips as near surface mounted reinforcement, primarily for strengthening applications. Nevertheless, in-depth understanding of the bond mechanism is still a challenging issue. This paper presents both experimental and analytical investigations undertaken to evaluate bond characteristics of near surface mounted carbon FRP (CFRP) strips. A total of nine concrete beams, strengthened with near surface mounted CFRP strips were constructed and tested under monotonic static loading. Different embedment lengths were used to evaluate the development length needed for effective use of near surface mounted CFRP strips. A closed-form analytical solution is proposed to predict the interfacial shear stresses. The model is validated by comparing t...}, number={3}, journal={Journal of Composites for Construction}, author={Hassan, T. and Rizkalla, S.}, year={2003}, pages={248–257} }
 @article{fam_rizkalla_2003, title={Large scale testing and analysis of hybrid concrete/composite tubes for circular beam-column applications}, volume={17}, ISSN={0950-0618}, url={http://dx.doi.org/10.1016/s0950-0618(03)00048-5}, DOI={10.1016/s0950-0618(03)00048-5}, abstractNote={Concrete-filled fiber reinforced polymer (FRP) circular tubes provide an effective structural system for a variety of applications such as piles, columns, overhead sign structures and utility poles. This paper discusses the behavior of concrete-filled Glass-FRP tubes ranging in diameter from 90 to 942 mm, using test results of eight beams, five columns and ten beam-column specimens. The effects of concrete fill, laminate structure of the tube, reinforcement ratio based on the wall thickness, as well as different failure modes are examined. Analytical models have been established and used in a parametric study to examine the effects of fiber orientation within the FRP tubes, thickness of the FRP tube, and the diameter of a central hole, which could be used to reduce the self-weight of the member. The benefits of concrete fill as well as the confinement effects have been demonstrated experimentally and analytically.}, number={6-7}, journal={Construction and Building Materials}, publisher={Elsevier BV}, author={Fam, Amir and Rizkalla, Sami}, year={2003}, month={Sep}, pages={507–516} }
 @article{fam_pando_filz_rizkalla_2003, title={Precast Piles for Route 40 Bridge in Virginia using Concrete-filled FRP Tubes}, volume={48}, number={3}, journal={PCI Journal}, author={Fam, A. and Pando, M. and Filz, G. and Rizkalla, S.}, year={2003}, month={May}, pages={32–45} }
 @article{abdelrahman_mohamadien_rizkalla_tadros_2003, title={Use of ACM in Rehabilitation Projects in Egypt}, volume={215}, journal={ACI Special Publications}, author={Abdelrahman, A. and Mohamadien, M. and Rizkalla, S. and Tadros, G.}, year={2003}, month={Nov}, pages={361–372} }
 @article{hutchinson_tadros_kroman_rizkalla_2003, title={Use of Externally Bonded FRP Systems for Rehabilitation of Bridges in Western Canada}, volume={SP–215}, journal={ACI Special Publications}, author={Hutchinson, R. and Tadros, G. and Kroman, J. and Rizkalla, S.}, year={2003}, month={Nov}, pages={239–248} }
 @article{fam_rizkalla_2002, title={Confinement Model for Axially Loaded Concrete Confined by Circular Fiber-Reinforced Polymer Tubes: Discussion and Closure}, volume={99}, number={3}, journal={ACI Structural Journal}, author={Fam, A. and Rizkalla, S.}, year={2002}, month={May}, pages={386–390} }
 @article{rizkalla_hassan_2002, title={Effectiveness of FRP for Strengthening Concrete Bridges}, volume={12}, ISSN={1016-8664 1683-0350}, url={http://dx.doi.org/10.2749/101686602777965577}, DOI={10.2749/101686602777965577}, abstractNote={This paper demonstrates an alternative use of FRP for strengthening concrete bridges in response to the demand towards increasing the flexural capacity to accommodate new truck loads. Several large-scale models of a prestressed concrete bridge were constructed and tested to failure to investigate the effectiveness of different FRP strengthening techniques. These techniques include near surface mounted bars and strips as well as externally bonded sheets and strips. Bond characteristics of near surface mounted FRP bars and strips are investigated by testing independently 17 concrete beams under monotonic static loading. Mathematical models for the interfacial shear stresses and the minimum anchorage length needed for near surface mounted bars and strips are presented. The feasibility of strengthening a prestressed concrete bridge using near surface mounting technique is discussed. The paper presents also an overview of the cost-effectiveness of each of the strengthening techniques considered in this study.}, number={2}, journal={Structural Engineering International}, publisher={Informa UK Limited}, author={Rizkalla, Sami and Hassan, Tarek}, year={2002}, month={May}, pages={89–95} }
 @article{bakis_bank_brown_cosenza_davalos_lesko_machida_rizkalla_triantafillou_2002, title={Fiber-Reinforced Polymer Composites in Construction- State-of-the-Art Review}, volume={6}, DOI={10.1061/(ASCE)1090-0268(2002)6:2(73)}, abstractNote={A concise state-of-the-art survey of fiber-reinforced polymer (also known as fiber-reinforced plastic) composites for construction applications in civil engineering is presented. The paper is organized into separate sections on structural shapes, bridge decks, internal reinforcements, externally bonded reinforcements, and standards and codes. Each section includes a historical review, the current state of the art, and future challenges.}, number={2}, journal={ASCE Journal of Composites for Construction}, author={Bakis, C. and Bank, L. and Brown, V. and Cosenza, E. and Davalos, J. and Lesko, J. and Machida, A. and Rizkalla, S. and Triantafillou, T.}, year={2002}, month={May}, pages={78–87} }
 @article{fam_rizkalla_2002, title={Flexural Behavior of concrete-filled fiber-reinforced polymer circular tubes}, volume={6}, DOI={10.1061/(ASCE)1090-0268(2002)6:2(123)}, abstractNote={This paper presents the experimental results of large-scale concrete-filled glass fiber-reinforced polymer (GFRP) circular tubes and control hollow GFRP and steel tubes tested in bending. The diameter of the beams ranged from 89 to 942 mm and the spans ranged from 1.07 to 10.4 m. The study investigated the effects of concrete filling, cross-sectional configurations including tubes with a central hole, tube-in-tube with concrete filling in between, and different laminate structures of the GFRP tubes. The study demonstrated the benefits of concrete filling and showed that a higher strength-to-weight ratio can be achieved by providing a central hole. The results indicated that the flexural behavior is highly dependent on the stiffness and diameter-to-thickness ratio of the tube and, to a much less extent, on the concrete strength. Test results suggest that the contribution of concrete confinement to the flexural strength is insignificant; however, the ductility of the member is improved. A strain compatibility model has been developed, verified by the experimental results, and used to provide a parametric study of the different parameters, significantly affecting the behavior. The parametric study covered a wide range of FRP sections filled with concrete, including under-reinforced, balanced, and over-reinforced sections.}, number={2}, journal={Journal of Composites for Construction}, author={Fam, A. Z. and Rizkalla, S. H.}, year={2002}, pages={123–132} }
 @article{hassan_rizkalla_2002, title={Flexural strengthening of prestressed bridge slabs with FRP systems}, volume={47}, ISSN={["0887-9672"]}, DOI={10.15554/pcij.01012002.76.93}, abstractNote={Fiber reinforced polymer (FRP) materials offer great potential for cost effective retrofitting of concrete structures. In response for the growing need for strengthening and rehabilitation of concrete structures and bridges, an experimental program was conducted to investigate the feasibility of using different strengthening techniques as well as different types of FRP for strengthening prestressed concrete members. Half scale models of a prestressed concrete bridge were constructed and tested to failure. The test specimens consisted of one simple span and two overhanging cantilevers. Each specimen was tested three times using a different load location in each case. The applicability of a nonlinear finite element analysis of post-tensioned bridge slabs strengthened with near surface mounted FRP reinforcement is enumerated.}, number={1}, journal={PCI JOURNAL}, author={Hassan, T and Rizkalla, S}, year={2002}, pages={76–93} }
 @article{fam_musiker_kowalsky_rizkalla_2002, title={In-plane testing of damaged masonry wall repaired with FRP}, volume={11}, DOI={10.1177/096369350201100602}, abstractNote={This paper describes the perfonnance of a masonry wall repaired with glass fibre reinforced polymer, GFRP sheets. The original reinforced clay brick masonry wall was tested under in-plane lateral cyclic loading. Failure occurred due to yielding of the steel reinforcement and crushing of the bricks. After epoxy injection of the cracks and patching of the missing portions, the wall was repaired using GFRP sheets, applied in the horizontal and vertical directions, on one face ofthe wall, including the joint between the wall and concrete footing. The repaired wall was tested to failure in the same manner of the original wall. The results show that the strength and displacement capacities of the wall were completely restored and even exceeded the original capacities.}, number={6}, journal={Advanced Composites Letters}, author={Fam, A. and Musiker, D. and Kowalsky, M. and Rizkalla, S.}, year={2002}, pages={277–283} }
 @article{gentile_svecova_rizkalla_2002, title={Timber beams strengthened with GFRP bars: Development and applications}, volume={6}, DOI={10.1061/(ASCE)1090-0268(2002)6:1(11)}, abstractNote={Repair and rehabilitation of infrastructure is becoming increasingly important for bridges due to material deterioration and limited capacity to accommodate current load levels. An experimental program was undertaken to study the flexural behavior of creosote-treated sawn Douglas fir timber beams strengthened with glass fiber-reinforced polymer (GFRP) bars. Twenty-two half-scale and four full-scale timber beams strengthened with GFRP were tested to failure. The percent reinforcement ratios were between 0.27 and 0.82%. Additional unreinforced timber beams were tested as control specimens. The results have shown that using the proposed experimental technique changed the failure mode from brittle tension to compression failure, and flexural strength increased by 18 to 46%. Research findings indicate the use of near-surface GFRP bars overcomes the effect of local defects in the timber and enhances the bending strength of the members. Based on the experimental results, an analytical model is proposed to predict the flexural capacity of both unreinforced and GFRP-reinforced timber beams. The article also reviews implementation of the proposed technique for strengthening a timber bridge near Winnipeg, Manitoba, Canada.}, number={1}, journal={Journal of Composites for Construction}, author={Gentile, C. and Svecova, D. and Rizkalla, S. H.}, year={2002}, pages={11–20} }
 @article{fam_rizkalla_2001, title={Behavior of axially loaded concrete-filled circular fiber-reinforced polymer tubes}, volume={98}, DOI={10.14359/10217}, abstractNote={The aim of this paper is to describe the structural behavior of concrete-filled glass fiber-reinforced polymer (GFRP) tubes subjected to axial loads. The research included completely- and partially-filled tubes with a central hole as well as a tube-in-tube system with concrete filling between the 2 tubes. The GFRP tubes were designed to provide strength in both axial and transverse directions and were axially loaded with the concrete core. The study showed that the strength and ductility of concrete are improved due to confinement using GFRP tubes. The highest confinement level was achieved for completely-filled tubes. Using a central hole lowers the confinement effect; however, using an inner tube can enhance the confinement for this type of member. Results show that loading of GFRP tubes reduces the confinement effectiveness. The effects of laminate structure, hole size, interface condition between the tube and the concrete core, stiffnes of the tube, and failure modes are discussed.}, number={3}, journal={ACI Structural Journal}, author={Fam, A. Z. and Rizkalla, S. H.}, year={2001}, pages={280–289} }
 @article{hassan_mohamedien_hassan_rizkalla_2001, title={Bond Performance of Different FRP Strengthening Systems}, volume={5}, number={2}, journal={P.S. Engineering Research Journal}, author={Hassan, T. and Mohamedien, M. and Hassan, N. and Rizkalla, S.}, year={2001}, pages={15–23} }
 @article{fam_rizkalla_2001, title={Confinement model for axially loaded concrete confined by circular fiber-reinforced polymer tubes}, volume={98}, DOI={10.14359/10288}, abstractNote={This paper introduces an analytical model to predict the behavior of axially loaded circular concrete columns confined by fiber-reinforced polymer (FRP) tubes. The model, an extension of an earlier confinement model for concrete confined by steel reinforcement, is based on equilibrium, compatibility conditions, and the biaxial strength failure criteria of FRP tubes. It can be used to predict the behavior of prefabricated FRP tubes totally or partially filled with concrete, as well as concrete wrapped with FRP sheets. The model can account for the case of axially loaded concrete core only as well as the composite section of the concrete core and FRP tube, and is verified by experimental results reported by the authors and other researchers. A parametric study is presented to examine the effect of stiffness of the FRP tube, the effect of loading the FRP tube axially, and the effect of presence of inner hole inside the concrete core. The study shows that increasing the central hole size reduces the confinement effect, increasing the stiffness of the tube improves the confinement, and axial loading of the FRP tube significantly reduces the confinement.}, number={4}, journal={ACI Structural Journal}, author={Fam, A. Z. and Rizkalla, S. H.}, year={2001}, pages={451–461} }
 @article{eddie_shalaby_rizkalla_2001, title={Glass fiber-reinforced polymer dowels for concrete pavements}, volume={98}, DOI={10.14359/10188}, abstractNote={Corrosion of steel dowels in concrete pavements reduces their useful service life and creates considerable maintenance and repair expenditures. Glass fiber-reinforced polymer (GFRP) dowel bars are a possible maintenance-free alternative that will potentially reduce the overall life cycle cost of pavements, especially in corrosive environments. This paper describes the performance of GFRP dowel bars under static and cyclic loads. Dowels were used for a slab/joint model tested under laboratory conditions. This paper also discusses the results of a field application in which 3 types of GFRP dowels were installed in a new concrete pavement highway in Winnipeg, Manitoba, Canada. The field performance of doweled joints has been verified under dynamic load testing.}, number={2}, journal={ACI Structural Journal}, author={Eddie, D. and Shalaby, A. and Rizkalla, S.}, year={2001}, pages={201–206} }
 @article{tennyson_mufti_rizkalla_tadros_benmokrane_2001, title={Structural health monitoring of innovative bridges in Canada with fiber optic sensors}, volume={10}, ISSN={0964-1726 1361-665X}, url={http://dx.doi.org/10.1088/0964-1726/10/3/320}, DOI={10.1088/0964-1726/10/3/320}, abstractNote={This paper describes the development and application of fiber optic sensors for monitoring bridge structures. Fiber Bragg gratings (FBGs) have been used to measure static and dynamic loads on bridge decks and columns, including composite repairs for rehabilitation purposes. A new long gage concept that permits overall average strains to be measured has also been developed with gage lengths varying from 1-20 m. These gages can be bonded to the concrete structure or imbedded in the composite repair patch. Six projects undertaken by ISIS Canada to incorporate fiber optic sensing to monitor the structural health of bridges in Canada are described. Data will be presented for several bridges that indicate a measure of system reliability over several years in a hostile environment. The benefits of fiber optic sensors will be highlighted.}, number={3}, journal={Smart Materials and Structures}, publisher={IOP Publishing}, author={Tennyson, R C and Mufti, A A and Rizkalla, S and Tadros, G and Benmokrane, B}, year={2001}, month={Jun}, pages={560–573} }
 @article{hassan_abdelrahman_tadros_rizkalla_2000, title={Fibre reinforced polymer reinforcing bars for bridge decks}, volume={27}, ISSN={0315-1468 1208-6029}, url={http://dx.doi.org/10.1139/l99-098}, DOI={10.1139/l99-098}, abstractNote={This paper describes the behaviour of two full-scale models of a portion of highway bridge slab reinforced with fibre reinforced polymer (FRP) reinforcement. The first slab was reinforced totally w...}, number={5}, journal={Canadian Journal of Civil Engineering}, publisher={Canadian Science Publishing}, author={Hassan, T and Abdelrahman, A and Tadros, G and Rizkalla, S}, year={2000}, month={Oct}, pages={839–849} }
 @article{shehata_morphy_rizkalla_2000, title={Fibre reinforced polymer shear reinforcement for concrete members: behaviour and design guidelines}, volume={27}, ISSN={0315-1468 1208-6029}, url={http://dx.doi.org/10.1139/l00-004}, DOI={10.1139/l00-004}, abstractNote={This paper describes an experimental program conducted to examine the structural performance of fibre reinforced polymer (FRP) stirrups as shear reinforcement for concrete structures. A total of ten large-scale reinforced concrete beams were tested to investigate the contribution of the FRP stirrups in a beam mechanism. The ten beams included four beams reinforced with carbon fibre reinforced polymer (CFRP) stirrups, four beams reinforced with glass fibre reinforced polymer (GFRP) stirrups, one beam reinforced with steel stirrups, and one control beam without shear reinforcement. The variables were the material type of stirrups, the material type of the flexural reinforcement, and the stirrup spacing. Due to the unidirectional characteristics of FRP, significant reduction in the strength of the stirrup relative to the tensile strength parallel to the fibres is introduced by bending FRP bars into a stirrup configuration and by the kinking action due to inclination of the diagonal shear crack with respect t...}, number={5}, journal={Canadian Journal of Civil Engineering}, publisher={Canadian Science Publishing}, author={Shehata, Emile and Morphy, Ryan and Rizkalla, Sami}, year={2000}, month={Oct}, pages={859–872} }
 @article{hassan_rizkalla_rihal_parmantier_2000, title={Segmental Precast Concrete Piles: A Solution For Underpinning}, volume={22}, number={8}, journal={ACI Concrete International}, author={Hassan, T. and Rizkalla, S. and Rihal, S. and Parmantier, D.}, year={2000}, month={Aug}, pages={41–46} }
 @article{abdelrahman_rizkalla_1999, title={Deflection Control of Concrete Beams Pretensioned by CFRP Reinforcements}, volume={3}, ISSN={1090-0268 1943-5614}, url={http://dx.doi.org/10.1061/(asce)1090-0268(1999)3:2(55)}, DOI={10.1061/(asce)1090-0268(1999)3:2(55)}, abstractNote={Use of carbon fiber reinforced polymers (CFRP) reinforcement for prestressing concrete structures introduces a promising solution for deterioration of concrete structures due to corrosion of steel reinforcements. Due to the low elastic modulus and limited strain at failure of CFRP reinforcement, partial prestressing could be the most appropriate approach to enhance deformability and reduce the cost in comparison to fully prestressed concrete structures. For members reinforced or prestressed with fiber reinforced polymers reinforcements, serviceability requirements may be the governing criteria for the design; therefore, deflection under service loading conditions should be well defined. This paper introduces simplified methods to calculate the deflection of beams prestressed by CFRP reinforcement under short-term and repeated loading. It also examines the applicability of current approaches available to calculate the deflection. Based on an experimental program undertaken at the University of Manitoba, bo...}, number={2}, journal={Journal of Composites for Construction}, publisher={American Society of Civil Engineers (ASCE)}, author={Abdelrahman, Amr A. and Rizkalla, Sami H.}, year={1999}, month={May}, pages={55–62} }
 @article{hassan_rizkalla_abdelrahman_tadros_1999, title={Design Recommendations for Bridge Deck Slabs Reinforced by FRP}, volume={SP-188}, journal={ACI Special Publications}, author={Hassan, T. and Rizkalla, S. and Abdelrahman, A. and Tadros, G.}, year={1999}, month={Nov}, pages={313–323} }
 @article{rizkalla_labossiére_1999, title={FRP Extends Service Life of Rehabilitated Infrastructure}, journal={Canadian Civil Engineer}, author={Rizkalla, S. and Labossiére, P.}, year={1999}, month={Sep}, pages={8–12} }
 @article{shehata_morphy_rizkalla_1999, title={FRP for Shear Reinforcement of Concrete Structures}, volume={SP-188}, journal={ACI Special Publications}, publisher={ACI Special Publications}, author={Shehata, E. and Morphy, R. and Rizkalla, S.}, year={1999}, month={Nov}, pages={157–167} }
 @article{shehata_rizkalla_1999, title={Intelligent Sensing for Innovative Bridges}, volume={10}, ISSN={1045-389X 1530-8138}, url={http://dx.doi.org/10.1177/1045389x9901000406}, DOI={10.1177/1045389x9901000406}, abstractNote={This paper discusses two types of fiber optic sensors used for monitoring highway bridges in Manitoba, Canada. The first, the Taylor Bridge, is the longest smart bridge built in North America and was completed in 1997. Four girders, large portions of the deck slab and the barrier wall are reinforced with carbon and glass fiber reinforced polymer (FRP) materials. The bridge is remotely monitored using fiber optic sensors embedded in the girders, the deck slab and the barrier wall to provide continuous information on the health and structural performance of the bridge. Signals obtained from the optical sensors are transmitted through a telephone line, thereby allowing an office-based engineer to monitor the stresses and strains via a computer anywhere in the world. The paper discusses the expert system program used to reduce the data collected from the bridge into engineering information which can be used to assess the performance of the FRP material and the behavior of the bridge. The second, the Norwood Bridge, is another innovative bridge also built in Winnipeg, Manitoba. The bridge is a complex precast reinforced concrete structure including an innovative mechanical connection at the supports to provide continuity. Monitoring of the bridge was requested by the owner, the City of Winnipeg, to verify structural behavior during different stages of construction and operation. A different type of fiber optic system was used in this bridge. Both the Taylor and the Norwood Bridge projects were undertaken by the Network of Centres of Excellence on Intelligent Sensing for Innovative Structures (ISIS Canada) which was able to provide the valuable link between the emerging new technology in structural remote monitoring and the construction industry.}, number={4}, journal={Journal of Intelligent Material Systems and Structures}, publisher={SAGE Publications}, author={Shehata, Emile and Rizkalla, Sami}, year={1999}, month={Apr}, pages={304–313} }
 @article{xie_kwan_chan_rizkalla_1999, title={Linseed Oil-Based Concrete Surface Treatment for Building and Highway Structures in Hong Kong}, volume={6}, ISSN={1023-697X 2326-3733}, url={http://dx.doi.org/10.1080/1023697x.1999.10667790}, DOI={10.1080/1023697x.1999.10667790}, abstractNote={This experimental program investigated the effectiveness of concrete surface treatment using four Canadian linseed oil-based sealants on concrete specimens made from G30/20 and G45/20 concretes, which are typically used for building and highway structures in Hang Kong. The tests were conducted at the University of Hong Kong and the University of Manitoba independently, using samples cost from the same mixes in Hong Kong. A total of more than 500 specimens were tested in each university for salt spray resistance, carbonation, bond strength, dripping and ultra-violet weathering. The results show that the four sealants were capable of penetrating through vertical, upward horizontal and downward horizontal concrete surfaces up to depths of 2.5 mm. All the four sealants significantly enhanced the resistance of G30/20 concrete against salt spray attack and carbonation. The resistance of G45/20 concrete to salt spray was also increased. Up to a duration limit of 500 hours of quick ultra-violet weathering, the tr...}, number={1}, journal={HKIE Transactions}, publisher={The Hong Kong Institution of Engineers}, author={Xie, Y P and Kwan, A K H and Chan, H C and Rizkalla, S H}, year={1999}, month={Jan}, pages={36–41} }
 @article{soudki_rizkalla_uppal_1999, title={Performance of Bridge Timber Ties Under Static and Fatigue Loading}, volume={4}, ISSN={1084-0702 1943-5592}, url={http://dx.doi.org/10.1061/(asce)1084-0702(1999)4:4(263)}, DOI={10.1061/(asce)1084-0702(1999)4:4(263)}, abstractNote={This study is in response to the dramatic increase in railway car axle loads that has occurred over the last 50 years. The paper presents the results of an experimental program undertaken to evaluate the structural performance of treated timber bridge ties under different railway car load levels. A portion of a prototype bridge deck, consisting of eight prototype timber bridge ties, was tested under various loading and support configurations to determine the axle load distribution. The serviceability of the treated bridge timber ties was evaluated based on the fatigue strength of eight prototype timber ties under different load levels. A theoretical model, based on energy principles, was developed to predict the axle load distribution to the ties for different span configurations. The model compares well with the measured test results and it complies with the American Railway Engineering Association requirements.}, number={4}, journal={Journal of Bridge Engineering}, publisher={American Society of Civil Engineers (ASCE)}, author={Soudki, Khaled A. and Rizkalla, Sami H. and Uppal, A. Shakoor}, year={1999}, month={Nov}, pages={263–268} }
 @article{hutchinson_rizkalla_1999, title={Shear Strengthening of AASHTO Bridge Girders Using CFRP Sheets}, volume={SP-188}, journal={ACI Special Publications}, author={Hutchinson, R. and Rizkalla, S.}, year={1999}, month={Nov}, pages={945–958} }
 @article{rizkalla_labossiére_1999, title={Structural Engineering with FRP-In Canada}, volume={21}, number={10}, journal={Concrete International}, author={Rizkalla, S. and Labossiére, P.}, year={1999}, month={Oct}, pages={25–28} }
 @article{mahmoud_rizkalla_zaghloul_1999, title={Transfer and Development Lengths of Carbon Fiber Reinforced Polymer Prestressing Reinforcement}, volume={96}, number={4}, journal={ACI Structural Journal}, author={Mahmoud, Z. and Rizkalla, S. and Zaghloul, E.}, year={1999}, month={Jul}, pages={594–602} }
 @article{rizkalla_shehata_abdelrahman_tadros_1998, title={A New Generation: Design and Construction of a Highway Bridge with CFRP}, volume={20}, number={6}, journal={Concrete International}, author={Rizkalla, S. and Shehata, E. and Abdelrahman, A. and Tadros, G.}, year={1998}, month={Jun}, pages={35–38} }
 @article{domenico_mahmoud_rizkalla_1998, title={Bond Properties of Carbon Fiber Composite Prestressing Strands}, volume={95}, number={3}, journal={ACI Structural Journal}, author={Domenico, N. and Mahmoud, Z. and Rizkalla, S.}, year={1998}, month={May}, pages={281–290} }
 @article{rizkalla_1998, title={Fiber Reinforced Plastic for Smart Bridge}, volume={19}, number={2}, journal={Engineering Dimensions}, author={Rizkalla, S.}, year={1998}, month={Mar}, pages={38} }
 @article{michaluk_rizkalla_tadros_benmokrane_1998, title={Flexural Behavior of One-Way Concrete Slab Reinforced by Fiber Reinforced Plastic Reinforcements}, volume={95}, DOI={10.14359/552}, abstractNote={Fiber Reinforced Plastic (FRP) reinforcements are currently used for special concrete structures in areas sensitive to magnetic fields and severe environmental conditions that accelerate corrosion of the steel reinforcements, and consequently leads to deterioration of the structure. This paper presents test results of eight one-way concrete slabs reinforced with glass-fiber, carbon-fiber, and conventional steel reinforcements. The slabs were tested under static loading conditions to determine their flexural and shear limit states, including the behavior prior to cracking, cracking, ultimate capacities, and modes of failure. Based on this investigation, design recommendations and guidelines are proposed.}, number={3}, journal={ACI Structural Journal}, author={Michaluk, C. and Rizkalla, S. and Tadros, G. and Benmokrane, B.}, year={1998}, month={May}, pages={353–365} }
 @article{shehata_rizkalla_stewart_1998, title={Roof Retrofit}, volume={20}, number={6}, journal={Concrete International}, author={Shehata, E. and Rizkalla, S. and Stewart, D.}, year={1998}, month={Jun}, pages={44–46} }
 @article{fam_rizkalla_tadros_1997, title={Behavior of CFRP for Prestressing and Shear Reinforcements of Concrete Highway Bridges}, volume={94}, number={1}, journal={ACI Structural Journal}, author={Fam, A. and Rizkalla, S. and Tadros, G.}, year={1997}, pages={77–86} }
 @article{maaskant_alavie_measures_tadros_rizkalla_guha-thakurta_1997, title={Fiber-optic Bragg grating sensors for bridge monitoring}, volume={19}, ISSN={0958-9465}, url={http://dx.doi.org/10.1016/s0958-9465(96)00040-6}, DOI={10.1016/s0958-9465(96)00040-6}, abstractNote={Fiber-optic Bragg grating strain sensors hold a great deal of potential for structural monitoring because of their exceptional stability and demonstrated potential for long-term monitoring. This sensing technology takes advantage of a spectrally encoded signal which provides inherent immunity from signal intensity fluctuations which plague many other fiber-optic and electronic sensing techniques. This results in measurement stability and lead/interconnect insensitivity which permit longterm and intermittent monitoring with high resolution and accuracy. Fiber-optic grating sensors are intrinsic to the optical fiber, thus capitalizing on its extremely small size and inherent strength and durability. Recent results are provided from a sensor array installed in a road bridge. The strain sensors are attached to both steel and carbon-fiber-reinforced plastic prestressing tendons, which are embedded in the precast girders of the bridge. Measurements of traffic loads and the relaxation behaviour of the tendons are presented. The potential of fiber grating technology is briefly discussed including its application in long-gage strain-sensing and strain-distribution measurements.}, number={1}, journal={Cement and Concrete Composites}, publisher={Elsevier BV}, author={Maaskant, R. and Alavie, T. and Measures, R.M. and Tadros, G. and Rizkalla, S.H. and Guha-Thakurta, A.}, year={1997}, month={Jan}, pages={21–33} }
 @article{hassan_mohamedien_rizkalla_1997, title={Multibolted Joints for GFRP Structural Members}, volume={1}, ISSN={1090-0268 1943-5614}, url={http://dx.doi.org/10.1061/(asce)1090-0268(1997)1:1(3)}, DOI={10.1061/(asce)1090-0268(1997)1:1(3)}, abstractNote={For the past few decades, aerospace industry was the major user of advanced composite materials. Recently, civil engineers and the construction industry began to realize the potential of these materials in providing remedies for many problems associated with deterioration and corrosion of infrastructures. In light of this, a comprehensive experimental investigation was conducted at the University of Manitoba to study the behavior of multibolted connections using glass fiber-reinforced plastic members. A total of 105 multibolted double shear lap connections were tested. The effect of various parameters including the width of the structural member, edge distance, number of bolts, bolt pattern, pitch, thickness of the members, and direction of fibers with respect to the applied load were examined. This paper analyzes the experimental program, test results, and the various modes of failure as affected by the previously noted parameters.}, number={1}, journal={Journal of Composites for Construction}, publisher={American Society of Civil Engineers (ASCE)}, author={Hassan, Nahla K. and Mohamedien, Mohamed A. and Rizkalla, Sami H.}, year={1997}, month={Feb}, pages={3–9} }
 @article{hassan_mohamedien_rizkalla_1997, title={Rational Model for Multibolted Connections for GFRP Members}, volume={1}, ISSN={1090-0268 1943-5614}, url={http://dx.doi.org/10.1061/(asce)1090-0268(1997)1:2(71)}, DOI={10.1061/(asce)1090-0268(1997)1:2(71)}, abstractNote={Bolted connections are most suitable for civil engineering applications since they are easy to inspect, have low construction costs, are easy to manufacture, and offer reliability compared with bonded joints. However, using advanced composite material members with unidirectional fibers could create a state of high stress concentration around the bolt holes due to their inherent geometric discontinuities. Due to a lack of information and the need for understanding the mechanism of these connections, a comprehensive experimental and analytical investigation was conducted at the University of Manitoba to study and to determine the behavior of bolted connections using glass fiber-reinforced plastic (GFRP) structural members. Based on the test results and observed behavior, a design procedure is introduced that accounts for the material orthotropy, pseudoyielding capability, and other factors that influence the connection behavior. The proposed rational model is capable of predicting the ultimate capacity of the multibolted connection and the failure mode. The generic nature of the proposed design guidelines can be applied to a multitude of composite material systems.}, number={2}, journal={Journal of Composites for Construction}, publisher={American Society of Civil Engineers (ASCE)}, author={Hassan, Nahla K. and Mohamedien, Mohamed A. and Rizkalla, Sami H.}, year={1997}, month={May}, pages={71–78} }
 @article{abdelrahman_rizkalla_1997, title={Serviceability of Concrete Beams Prestressed by Carbon Fiber Reinforced Plastic Bars}, volume={94}, number={4}, journal={ACI Structural Journal}, author={Abdelrahman, A. and Rizkalla, S.}, year={1997}, month={Jul}, pages={447–457} }
 @article{hassan_mohamedien_rizkalla_1996, title={Finite element analysis of bolted connections for PFRP composites}, volume={27}, ISSN={1359-8368}, url={http://dx.doi.org/10.1016/1359-8368(95)00046-1}, DOI={10.1016/1359-8368(95)00046-1}, abstractNote={Structural applications of composite laminates are increasing with the drive for high strength, lightweight component design. These applications usually require joining composites either to composites or metals. Most commonly, joints are formed using mechanical fasteners. Therefore suitable prediction methods must be developed to determine failure strength and failure modes of these bolted connections. In this paper, three-dimensional finite element analysis is conducted on single and multi-bolted connections to determine the failure process, ultimate load and load distribution among the fasteners, taking into consideration bolt-hole contact problem in the finite element model. The strength analysis is based on Tsai-Wu tensor polynomial failure criterion which is applied to the laminate as a whole.}, number={3-4}, journal={Composites Part B: Engineering}, publisher={Elsevier BV}, author={Hassan, Nahla K. and Mohamedien, Mohamed A. and Rizkalla, Sami H.}, year={1996}, month={Jan}, pages={339–349} }
 @article{soudki_west_rizkalla_blackett_1996, title={Horizontal Connections for Precast Concrete Shear Wall Panels Under Cyclic Shear Loading}, volume={41}, number={3}, journal={PCI Journal}, author={Soudki, K. and West, J. and Rizkalla, S. and Blackett, B.}, year={1996}, month={May}, pages={64–72} }
 @article{rosner_rizkalla_1995, title={Bolted Connections for Fiber-Reinforced Composite Structural Members: Analytical Model and Design Recommendations}, volume={7}, ISSN={0899-1561 1943-5533}, url={http://dx.doi.org/10.1061/(asce)0899-1561(1995)7:4(232)}, DOI={10.1061/(asce)0899-1561(1995)7:4(232)}, abstractNote={The use of fiber–reinforced composite materials in civil structural applications is relatively new and there is a serious lack of information on the behavior and design of the bolted connections normally used for structural members. As a result, a comprehensive experimental and analytical investigation was conducted at the University of Manitoba to study and determine the behavior of bolted connections in composite materials used for civil engineering applications. Based on the research findings and observed behavior, a design procedure is introduced, which accounts for material orthotropy, pseudo–yielding capability, and other factors that influence bolted–connection behavior. The proposed model is capable of predicting the ultimate capacity and the mode of failure of the connections. Because of the generic nature of the model, the design guidelines can be applied to a multitude of composite material systems. Due to the model‘s simplicity, the proposed design procedure is ideal for implementation in design codes.}, number={4}, journal={Journal of Materials in Civil Engineering}, publisher={American Society of Civil Engineers (ASCE)}, author={Rosner, Charles N. and Rizkalla, Sami H.}, year={1995}, month={Nov}, pages={232–238} }
 @article{soudki_rizkalla_leblanc_1995, title={Horizontal Connections for Precast Concrete Shear Walls Subjected to Cyclic Deformations Part 1: Mild Steel Connections}, volume={40}, ISSN={0887-9672}, url={http://dx.doi.org/10.15554/pcij.07011995.78.96}, DOI={10.15554/pcij.07011995.78.96}, abstractNote={This paper represents the second part of a multiphase experimental program undertaken at the University of Manitoba to study the cyclic behavior of prestressed connections for precast concrete shear walls. The first part of the study dealt with the behavior of mild steel connections. In this paper, the results of testing five full-scale prestressed connections subjected to reversed cyclic combined flexure and shear loads are presented. The connections were also subjected to axial stresses normal to the connection to simulate gravity loads. The paper discusses the influence of cyclic vs. monotonic loading, use of prestressed strands vs. prestressed bars and the effect of fully unbonded prestressed bars on the behavior of the connections. Based on the test results, design recommendations for the prestressed connection in seismic zones are presented. A simple analytical procedure is developed to predict the envelope of cyclic response and a numerical design example is included to illustrate the design procedure.}, number={4}, journal={PCI Journal}, publisher={Precast/Prestressed Concrete Institute}, author={Soudki, Khaled A. and Rizkalla, Sami H. and LeBlanc, Bill}, year={1995}, month={Jul}, pages={78–96} }
 @article{soudki_rizkalla_daikiw_1995, title={Horizontal Connections for Precast Concrete Shear Walls Subjected to Cyclic Deformations Part 2: Prestressed Connections}, volume={40}, ISSN={0887-9672}, url={http://dx.doi.org/10.15554/pcij.09011995.82.96}, DOI={10.15554/pcij.09011995.82.96}, abstractNote={82 Vice President and General Manager Lafarge Construction Materials A Division of Lafarge Canada Inc. Winnipeg, Manitoba, Canada This paper represents the second part of a multiphase experimental program undertaken at the University of Manitoba to study the cyclic behavior of prestressed connections for precast concrete shear walls. The first part of the study dealt with the behavior of mild steel connections. In this paper, the results of testing five full-scale prestressed connections subjected to reversed cyclic combined flexure and shear loads are presented. The connections were also subjected to axial stresses normal to the connection to simulate gravity loads. The paper discusses the influence of cyclic vs. monotonic loading, use of prestressed strands vs. prestressed bars and the effect of fully unbonded prestressed bars on the behavior of the connections. Based on the test results, design recommendations for the prestressed connection in seismic zones are presented. A simple analytical procedure is developed to predict the envelope of cyclic response and a numerical design example is included to illustrate the design procedure.}, number={5}, journal={PCI Journal}, publisher={Precast/Prestressed Concrete Institute}, author={Soudki, Khaled A. and Rizkalla, Sami H. and Daikiw, Robert W.}, year={1995}, month={Sep}, pages={82–96} }
 @article{abdelrahman_tadros_rizkalla_1995, title={Test Model for the First Canadian Smart Highway Bridge}, volume={92}, number={4}, journal={ACI Structural Journal}, author={Abdelrahman, A. and Tadros, G. and Rizkalla, S.}, year={1995}, month={Jul}, pages={451–458} }
 @article{tadros_rizkalla_1994, title={First Canadian Highway Bridge Prestressed by Carbon Fiber Strands and Monitored by Optical Fiber Sensors}, journal={Canadian Civil Engineer}, author={Tadros, G. and Rizkalla, S.}, year={1994}, month={Mar}, pages={7–15} }
 @article{tadros_rizkalla_1994, title={First Smart Highway Bridge in Canada}, volume={16}, number={6}, journal={Concrete International}, author={Tadros, G. and Rizkalla, S.}, year={1994}, month={Jun}, pages={42–44} }
 @article{wright_shen_rizkalla_1993, title={A three-year field and laboratory evaluation of linseed oil as a concrete sealer}, volume={20}, ISSN={0315-1468 1208-6029}, url={http://dx.doi.org/10.1139/l93-110}, DOI={10.1139/l93-110}, abstractNote={Sealers are used to enhance concrete durability through their ability to prevent moisture penetration and chloride intrusion, and, consequently, improve the freeze–thaw performance of the concrete and prevent corrosion of the steel reinforcement, respectively. This paper summarizes the results of three years of comprehensive field and laboratory investigations, undertaken at The University of Manitoba, to study the effectiveness of boiled linseed oil and mineral spirits in comparison to a silane and a siloxane sealer. The field investigation examined the performance of the sealers applied to the concrete pavements of a city street, a provincial highway, and an airport apron in Winnipeg, Manitoba. The laboratory investigation included sealer penetration, salt-water absorption and vapour transmission, abrasion, chloride ion intrusion, surface scaling resistance, and rapid freeze–thaw cycling. Test results of the field and laboratory investigation indicated that boiled linseed oil and mineral spirits was the...}, number={5}, journal={Canadian Journal of Civil Engineering}, publisher={Canadian Science Publishing}, author={Wright, J. and Shen, Z. and Rizkalla, S.}, year={1993}, month={Oct}, pages={844–854} }
 @article{erki_rizkalla_1993, title={Anchorages for FRP Reinforcement}, volume={15}, number={6}, journal={Concrete International}, publisher={Concrete International}, author={Erki, M.A. and Rizkalla, S.}, year={1993}, month={Jun}, pages={54–59} }
 @article{erki_rizkalla_1993, title={FRP Reinforcements for Concrete Structures: A Sample of International Production}, volume={15}, number={6}, journal={Concrete International}, author={Erki, M.A. and Rizkalla, S.}, year={1993}, month={Jun}, pages={48–53} }
 @article{hutchinson_rizkalla_lau_heuvel_1991, title={Horizontal Post-Tensioned Connections for Precast Concrete Load bearing Shear Wall Panels}, volume={36}, ISSN={0887-9672}, url={http://dx.doi.org/10.15554/pcij.11011991.64.76}, DOI={10.15554/pcij.11011991.64.76}, abstractNote={This paper presents the results of nine prototype specimens tested to investigate the behavior and capacity of post-tensioned horizontal connections typically used for precast loadbearing shear wall panels subjected to monotonic shear loading. Shear walls supporting hollow-core floor slabs were included. Two different levels of load normal to the connection were used to simulate the effects of gravity and permanent loading conditions. Test results were used to refine and calibrate rational mathematical models developed to predict the maximum shear capacity and the nominal shear strength of the connection. Various failure mechanisms are presented and discussed. A numerical design example is included to show the application of the proposed mathematical model. concrete construction adverse weather con high concrete shear and transverse}, number={6}, journal={PCI Journal}, publisher={Precast/Prestressed Concrete Institute}, author={Hutchinson, Robin L. and Rizkalla, Sami H. and Lau, Mike and Heuvel, Scott}, year={1991}, month={Nov}, pages={64–76} }
 @article{uppal_pinkney_rizkalla_1990, title={An analytical approach for dynamic response of timber railroad bridges}, volume={17}, ISSN={0315-1468 1208-6029}, url={http://dx.doi.org/10.1139/l90-107}, DOI={10.1139/l90-107}, abstractNote={The purpose of this paper is to describe briefly the analytical approach used for determining the dynamic response of timber railway bridge spans. The predicted loads at the wheel-rail interfaces, vertical displacements, and accelerations at the midpoints of a ballast-deck span and an open-deck span are compared with those obtained experimentally. The analysis is used further to study the effects of other parameters, such as the train speed and the train consist, on the dynamic behaviour of the spans. (A)}, number={6}, journal={Canadian Journal of Civil Engineering}, publisher={Canadian Science Publishing}, author={Uppal, A. S. and Pinkney, R. B. and Rizkalla, S. H.}, year={1990}, month={Dec}, pages={952–964} }
 @article{polyzois_charnvarnichborikarn_rizkalla_wong_1990, title={Effect of temperature and galvanization on the compressive strength of cold-formed angles}, volume={17}, ISSN={0315-1468 1208-6029}, url={http://dx.doi.org/10.1139/l90-048}, DOI={10.1139/l90-048}, abstractNote={An experimental program was conducted at The University of Manitoba to investigate the effect of subfreezing temperatures and galvanization on the compressive strength of cold-formed steel angles. ...}, number={3}, journal={Canadian Journal of Civil Engineering}, publisher={Canadian Science Publishing}, author={Polyzois, D. and Charnvarnichborikarn, P. and Rizkalla, S. and Wong, C. K.}, year={1990}, month={Jun}, pages={440–451} }
 @article{uppal_rizkalla_pinkney_1990, title={Response of timber bridges under train loading}, volume={17}, ISSN={0315-1468 1208-6029}, url={http://dx.doi.org/10.1139/l90-106}, DOI={10.1139/l90-106}, abstractNote={Timber bridges are still commonly used by several North American railroads. For short spans, they offer attractive alternatives to other types of bridges because they are more economical, faster to construct, and easy to maintain. Current design practices do not allow independent consideration of the effects of dynamic loads in sizing bridge components. The main objective of this paper is to describe the experimental work conducted to study the behavior of timber bridge spans under the passage of trains at different speeds. Tests were conducted on two types of bridge spans, a ballast deck and an open deck. Test results indicate the response of spans and the effects of other parameters such as speed and static wheel loads to dynamic factors.}, number={6}, journal={Canadian Journal of Civil Engineering}, publisher={Canadian Science Publishing}, author={Uppal, A. S. and Rizkalla, S. H. and Pinkney, R. B.}, year={1990}, month={Dec}, pages={940–951} }
 @article{foerster_rizkalla_heuvel_1989, title={Behavior and Design of Shear Connections for Loadbearing Wall Panels}, volume={34}, ISSN={0887-9672}, url={http://dx.doi.org/10.15554/pcij.01011989.102.119}, DOI={10.15554/pcij.01011989.102.119}, abstractNote={D inring the past decade, use of precast loadbearing shear wall panels for high rise construction has become very popular due to the high quality control achieved at the precast concrete manufacturing plant and the ease of panel assembly and erection at the project site (Fig. 1). In the structure, the precast panels are tied together using continuity reinforcement bars and mechanical shear connectors. The gap between the panels, which is required for alignment, is normally filled with a dry pack grout. This grouting system eliminates the use of falsework and minimizes the use of temporary supports. Current design sources'3 provide only limited information about the behavior and ultimate shear carrying capacity of the connections described in this paper. The information available in the literaturelo mainly describes the shear friction mechanism and the dowel action of initially cracked concrete to concrete surfaces. The results of such studies cannot be directly applicable to the predescribed connections due to the presence of the dry pack grout layer between the two concrete surfaces.}, number={1}, journal={PCI Journal}, publisher={Precast/Prestressed Concrete Institute}, author={Foerster, Harry R. and Rizkalla, Sami H. and Heuvel, J. Scott}, year={1989}, month={Jan}, pages={102–119} }
 @article{rizkalla_serrette_heuvel_attiogbe_1989, title={Multiple Shear Key Connections for Precast Shear Wall Panels}, volume={34}, ISSN={0887-9672}, url={http://dx.doi.org/10.15554/pcij.03011989.104.120}, DOI={10.15554/pcij.03011989.104.120}, abstractNote={P recast concrete shear wall panels are used extensively in high rise construction. Their attractiveness and economy are mainly due to the high quality control that is achieved at the manufacturing plant, and the ease and speed of panel assembly at the construction site. One of the main concerns in precast concrete construction is the method by which the panels are connected. Connections must provide adequate strength, ductility and continuity in order to insure the integrity of the structure under various loading conditions. The typical connections currently used for elevator shaft shear wall panels}, number={2}, journal={PCI Journal}, publisher={Precast/Prestressed Concrete Institute}, author={Rizkalla, Sarni H. and Serrette, Reynaud L. and Heuvel, J. Scott and Attiogbe, Emmanuel K.}, year={1989}, month={Mar}, pages={104–120} }
 @article{pincheira_rizkalla_attiogne_1989, title={Performance of Welded Wire Fabric as Shear Reinforcement Under Cyclic Loading}, volume={86}, ISSN={0889-3241}, url={http://dx.doi.org/10.14359/2770}, DOI={10.14359/2770}, abstractNote={The performance of welded wire fabric (WWF) as shear reinforcement in prestressed and reinforced concrete T-beams subjected to cyclic loading is investigated and compared to that of convenlional stirrups. Ultimate strength, ductility, crack width control, and anchorage of the web reinforcement were used to evaluate the effectiveness of the WWF as shear reinforcement. Test results indicate that WWF provides a slightly better control of crack width in comparison to an equivalent amount of either singleor double-legged stirrups. Anchorage of WWF provided by two horizontal wires at the top and bot/om of the vertical wires appears to be adequate under cyclic loading. However, premature fracture of the vertical wires at the welded intersections reduced the ultimate strength of the member in comparison to that of the beams reinforced with conventional stirrups. Test results also show that the current provisions of the ACI Building Code overestimate the shear load corresponding to the initiation oj diagonal cracking for members subjected to cyclic loading. Therefore, the use of a minimum amount of web reinforcement should be mandatory when repetitive loading is expected. ~}, number={6}, journal={ACI Structural Journal}, publisher={American Concrete Institute}, author={Pincheira, Jose A. and Rizkalla, Sami H. and Attiogne, Emmanuel K.}, year={1989}, pages={728–735} }
 @article{xuan_rizkalla_1989, place={United Kingdom}, title={Welded wire shear reinforcement under cyclic loading}, volume={16}, DOI={10.1080/01823328808726884}, abstractNote={Describes research at the University of Manitoba, financed by the Canadian National Science and Engineering Research Council, to test the behaviour under cyclic loading of this fabric used as shear reinforcement. Its effectiveness proved similar to that of conventional single‐legged stirrups, and anchorage by top and bottom horizontal wires was adequate. The shear capacity of the prestressed beams tested deteriorated much faster than the flexural capacity.}, number={3}, journal={Batiment International, Building Research and Practice}, publisher={The International Council for Building Research, Studies and Documentation}, author={Xuan, X. and Rizkalla, S.}, year={1989}, pages={161–166} }
 @article{xuan_rizkalla_maruyama_1988, title={Effectiveness of Welded Wire Fabric as Shear Reinforcement in Pretensioned Prestressed Concrete T-Beams}, volume={85}, DOI={10.14359/2711}, abstractNote={A lotal 0/ six pretensioned prestressed single T-beams with identical flexural reinforcements and shear span-la-depth ratio were tested statically up to failure to investigate the effectiveness oj welded wire fabric as shear reinforcement. The tested beams featured one beam without shear reinforcement and five beams with different types of shear reinforcement. including conventional double-legged stirrups, single-legged stirrups, and three different types of commercially available welded wire fabric (WWF). The results indicated that the effectiveness of WWF as shear reinforcement is the same as that of conventional stirrups under static loading conditions. It was found that using deformed WWF slightly improved the distribution of the diagonal cracks. Anchorages of WWF by means of two horizontal wires at the top and bottom are adequate according to A CI Building Code recommendations.}, number={4}, journal={ACI Structural Journal}, author={Xuan, X. and Rizkalla, S. and Maruyama, K.}, year={1988}, month={Jul}, pages={429–436} }
 @article{attiogbe_rizkalla_1988, title={Response of Concrete to Sulphuric Acid Attack}, volume={85}, number={6}, journal={ACI Material Journal}, author={Attiogbe, E. and Rizkalla, S.}, year={1988}, month={Nov}, pages={481–488} }
 @article{uppal_rizkalla_1988, title={Response of Timber Bridges under Train Loading}, number={1177}, journal={Transportation Research Record}, author={Uppal, A.S. and Rizkalla, S.H.}, year={1988}, pages={103–112} }
 @article{maruyama_rizkalla_1988, title={Shear Design Consideration for Pretensioned Prestressed Beams}, volume={85}, number={5}, journal={ACI Structural Journal}, author={Maruyama, K. and Rizkalla, S.}, year={1988}, month={Sep}, pages={492–498} }
 @article{serrette_rizkalla_heuvel_1988, title={Shear Resistance of Various Connections used for Precast Concrete Load-Bearing Shear Wall Panels}, volume={10}, number={3}, journal={Transactions of the Japan Concrete Institute}, author={Serrette, R.L. and Rizkalla, S. and Heuvel, J.S.}, year={1988}, pages={739–744} }
 @article{mcculloch_militano_rizkalla_1987, title={Behavioral load testing of the Disraeli facility}, volume={14}, ISSN={0315-1468 1208-6029}, url={http://dx.doi.org/10.1139/l87-013}, DOI={10.1139/l87-013}, abstractNote={L'echangeur Disraeli, qui fut complete en 1960, consiste en plusieurs viaducs utilisant une construction de poutres d'acier et d'un a poutres de plaques d'acier rivetees traversant la riviere Rouge a Winnipeg (Manitoba). La longueur totale de l'echangeur est approximativement de 707 m. On a complete un essai de charge sur l'echangeur pour confirmer la possibilite d'augmenter la limite maximale du poids brut d'un vehicule. Trois travees ont ete essayees. Une travee normale et une oblique ont ete selectionnees pour les viaducs de facon a etudier les differences possibles dans leur comportement. Description du plan d'installation de l'instrumentation du systeme d'acquisition des donnees, les vehicules et les procedes d'essais}, number={1}, journal={Canadian Journal of Civil Engineering}, publisher={Canadian Science Publishing}, author={McCulloch, W. J. and Militano, C. and Rizkalla, S.}, year={1987}, month={Feb}, pages={103–110} }
 @article{ray_rizkalla_1987, title={Discussion of “Transverse Stirrup Spacing in R/C Beams” by Wayne Hsiung and Gregory C. Frantz (February, 1985, Vol. 111, No. 2)}, volume={113}, number={1}, journal={Structural Engineering Journal}, author={Ray, A. and Rizkalla, S.}, year={1987}, month={Jan}, pages={174–175} }
 @article{domaschuk_rizkalla_kwok_1987, title={Inadequate shallow foundations}, volume={15}, ISSN={0182-3329}, url={http://dx.doi.org/10.1080/09613218708726821}, DOI={10.1080/09613218708726821}, abstractNote={A research study of damage to houses in Winnipeg, Canada, revealed that 94 percent had suffered some distress from shifting of the shallow‐footings foundations; the houses are of the typical Canadian pattern with basement areas. Discussed here are the details of the design study, with cost analyses, of five main foundation methods; the ‘best buy’, it is concluded, would be an optimised pile system, with basement walls designed as grade beams, supporting a timber main floor.}, number={1-6}, journal={Batiment International, Building Research and Practice}, publisher={Informa UK Limited}, author={Domaschuk, L. and Rizkalla, S. and Kwok, R.}, year={1987}, month={Jan}, pages={224–230} }
 @article{maruyama_rizkalla_1987, title={Shear Behavior of Pretensioned Prestressed Concrete Beams}, volume={9}, journal={Transactions of the Japan Concrete Institute}, author={Maruyama, K. and Rizkalla, S.}, year={1987}, pages={411–416} }
 @article{xuan_rizkalla_1987, title={Shear Strength of Prestressed Concrete T-beams with Welded Wire Fabric as Shear Reinforcement, Discussion}, volume={32}, number={6}, journal={PCI Journal}, author={Xuan, X. and Rizkalla, S.}, year={1987}, month={Nov}, pages={142–143} }
 @article{tinkler_del frate_rizkalla_1987, title={The prediction of air leakage rates through cracks in pressurized reinforced concrete containment vessels}, volume={29}, ISSN={0308-0161}, url={http://dx.doi.org/10.1016/0308-0161(87)90037-8}, DOI={10.1016/0308-0161(87)90037-8}, abstractNote={Measurements of air leakage through cracks in specimens of reinforced concrete were analysed on the basis that the compressible flow occurred without heat transfer between the air and the concrete. The resultant friction coefficients were then correlated with the crack size and roughness parameters. The empirical relations were rearranged so that leakage rates could be predicted for a gas with known properties passing through cracks of known average dimensions. Checking the predicted leakage against the measured leakage rates gave agreement within ±35%, the scatter being attributable to the very irregular nature of cracks. The method presented for the prediction of leakage can be used with confidence for typical cracks in reinforced concrete containment vessels.}, number={1}, journal={International Journal of Pressure Vessels and Piping}, publisher={Elsevier BV}, author={Tinkler, J. and Del Frate, R. and Rizkalla, S.}, year={1987}, month={Jan}, pages={33–46} }
 @article{rizkalla_saadat_higai_1985, title={Fundamental Characteristics and Behavior of Reinforced Concrete Bridge Piers Subjected to Reversed Cyclic Loading}, journal={Transportation Research Record 1044}, publisher={National Research Council}, author={Rizkalla, S. and Saadat, F. and Higai, T.}, year={1985}, month={Dec}, pages={17–25} }
 @article{rizkalla_lau_simmonds_1984, title={Air Leakage Characteristics in Reinforced Concrete}, volume={110}, ISSN={0733-9445 1943-541X}, url={http://dx.doi.org/10.1061/(asce)0733-9445(1984)110:5(1149)}, DOI={10.1061/(asce)0733-9445(1984)110:5(1149)}, abstractNote={Eight reinforced concrete specimens were fabricated and subjected to tensile membrane forces and air pressure to study the air leakage characteristics in cracked reinforced concrete members. A mathematical expression for the rate of pressurized air flowing through an idealized crack is presented. The mathematical expression is refined by using the experimental data to describe the air flow rate through any given crack pattern. Graphical charts are also presented for the calculation of the air leakage rate through concrete cracks. The concept of equivalent crack width for a given crack pattern is introduced. The mathematical expression and graphical charts are modified to include this equivalent crack width concept. The proposed technique is applicable for the prediction of the leakage from concrete containment structures or any similar structures due to high internal pressure sufficient to initiate cracking.}, number={5}, journal={Journal of Structural Engineering}, publisher={American Society of Civil Engineers (ASCE)}, author={Rizkalla, Sami H. and Lau, Bon L. and Simmonds, Sidney H.}, year={1984}, month={May}, pages={1149–1162} }
 @article{rizkalla_hwang_1984, title={Crack Prediction for Members in Uniaxial Tension}, volume={81}, number={6}, journal={Journal of the American Concrete Institute}, author={Rizkalla, S. and Hwang, L.}, year={1984}, month={Nov}, pages={572–579} }
 @article{rizkalla_simmonds_macgregor_1984, title={Cracking of P/C Nuclear Containment Structures}, volume={110}, ISSN={0733-9445 1943-541X}, url={http://dx.doi.org/10.1061/(asce)0733-9445(1984)110:9(2148)}, DOI={10.1061/(asce)0733-9445(1984)110:9(2148)}, abstractNote={Rules for determining the spacing and widths of both through-the-wall and surface cracks in post-tensioned concrete containment structures under internal pressure are presented. These involve the construction details and the average strain obtained from an analysis that accounts for concrete properties in the post-cracking range. To evaluate these rules and the concrete constitutive relationship used in the analysis, twelve quarterscale segments were designed to simulate construction and stress conditions at various locations of a containment structure. Major variables included ratio of prestressing, concrete cover, reinforcement spacing, lap splices and combined axial load and moment. It was observed that the crack spacing depended on the spacing of the reinforcement and prestressing tendons parallel to the cracks and that the final crack pattern was fully developed at the yield strain of the reinforcing steel. Concrete cover was not found to have a significant influence on crack spacing. The procedures developed to determine crack spacing and widths are used to predict the cracking of a one-fourteenth scale model of a containment structure tested later in the research project.}, number={9}, journal={Journal of Structural Engineering}, publisher={American Society of Civil Engineers (ASCE)}, author={Rizkalla, Sami H. and Simmonds, Sidney H. and MacGregor, James G.}, year={1984}, month={Sep}, pages={2148–2163} }
 @article{rizkalla_keeler_1984, title={Precast Concrete in Remote Locations}, volume={6}, number={11}, journal={Concrete International}, author={Rizkalla, S. and Keeler, R.K.}, year={1984}, month={Nov}, pages={41–42} }
 @article{rizkalla_simmonds_macgregor_1984, title={Prestressed Concrete Containment Model}, volume={110}, ISSN={0733-9445 1943-541X}, url={http://dx.doi.org/10.1061/(asce)0733-9445(1984)110:4(730)}, DOI={10.1061/(asce)0733-9445(1984)110:4(730)}, abstractNote={The construction and testing of a model of a prestressed concrete containment structure is described. The test structure consisted of a reinforced concrete base, cylindrical wall, ring beam and dome built of prestressed concrete with construction details patterned after the Canadian CANDU reactor containment. The overall height above the base was 12 ft‐6 in. (3,810 mm), and the outer diameter was 10 ft‐6 in. (3,200 mm). Internal pressure was obtained using water, and leakage was prevented by using a flexible plastic liner. Mea‐, surements made during the test included internal pressure, steel and concrete strains, crack widths and spacing, and curvatures at the base of the cylindrical wall. The test structure began to exhibit cracking at a pressure of. 30 psi (0.28 MPa), and yielding of the reinforcement at approximately 110 psi (0.76 MPa). The structure displayed considerable ductility before failing at internal pressure of 159 psi (1.10 MPa) by rupture of three horizontal tendons at midheight of the wal...}, number={4}, journal={Journal of Structural Engineering}, publisher={American Society of Civil Engineers (ASCE)}, author={Rizkalla, Sami H. and Simmonds, Sidney H. and MacGregor, James G.}, year={1984}, month={Apr}, pages={730–743} }
 @article{higai_omran_saadat_rizkalla_1984, title={Shear Failure of R.C. Members Subjected to Large Deflection Reversals}, journal={Transactions of the Japan Concrete Institute}, author={Higai, T. and Omran, B. and Saadat, F. and Rizkalla, S.}, year={1984}, month={Jun}, pages={505–508} }
 @article{keeler_rizkalla_1983, title={Rapid erection of a concentrate loading facility using precast concrete in a remote location}, volume={10}, ISSN={0315-1468 1208-6029}, url={http://dx.doi.org/10.1139/l83-073}, DOI={10.1139/l83-073}, abstractNote={This paper presents the design concept and construction details of a concentration loading facility in northern Manitoba under adverse conditions. The facility was constructed using plant-produced structural components which had to be shipped by rail to the site and assembled using the post-tensioning technique to provide structural integrity.The main elements of the structure were precast footings, precast retaining walls, and precast, prestressed channel-shaped girders. The project described in the paper is an efficient design highlighted by quality control and significant saving in construction time. The concept lends itself to many types of loading and storage facilites for remote locations.}, number={3}, journal={Canadian Journal of Civil Engineering}, publisher={Canadian Science Publishing}, author={Keeler, R. D. and Rizkalla, S. H.}, year={1983}, month={Sep}, pages={456–465} }
 @article{rizkalla_hwang_shahawi_1983, title={Transverse reinforcement effect on cracking behaviour of R.C. members}, volume={10}, ISSN={0315-1468 1208-6029}, url={http://dx.doi.org/10.1139/l83-087}, DOI={10.1139/l83-087}, abstractNote={Two extensive and independent experimental programs have been conducted to study the cracking behaviour of reinforced concrete members subjected to pure tension in the presence of transverse reinfo...}, number={4}, journal={Canadian Journal of Civil Engineering}, publisher={Canadian Science Publishing}, author={Rizkalla, S. H. and Hwang, L. S. and Shahawi, M. El}, year={1983}, month={Dec}, pages={566–581} }
 @article{rizkalla_zia_1980, title={Segmentally Constructed Prestressed Concrete Hyperboloid Cooling Tower}, volume={25}, ISSN={0887-9672}, url={http://dx.doi.org/10.15554/pcij.07011980.146.161}, DOI={10.15554/pcij.07011980.146.161}, abstractNote={I many large capacity power plant facilities, the natural draft cooling tower in the fonn of a thin shell of revolution is often required to di~sipate a large amount of heat. Construction of such large reinforced concrete natural draft cooling towers is expensive and time-consuming. The cost of the structure is strongly influenced by the construction technique. A possible means of reducing this cost is the technique of segmental construction in which the benefits of both precasting and post-tensioning can be combined together advantageously. This paper presents the concept of segmental construction as applied to the hyperboloid natural draft cooling tower and the method of analysis and design which have been developed in detail by Rizkalla.1 The structural behavior under gravity load, wind pressure and prestressing force is examined. The analysis is based on the finite element method using a truncated conical shell as the basic element. A numerical example is included to illustrate the design method. A conservative cost estimate indicates that there is a potential saving up to 40 percent of the cost of the tower (excluding foundations and columns) by means of segmental construction. Tower Geometry}, number={4}, journal={PCI Journal}, publisher={Precast/Prestressed Concrete Institute}, author={Rizkalla, Sami H. and Zia, Paul}, year={1980}, month={Jul}, pages={146–161} }
 @article{zia_mirza_rizkalla_1976, title={Static and Fatigue Tests of Composite T-Beams Containing Prestressed Concrete Tension Elements}, volume={21}, ISSN={0887-9672}, url={http://dx.doi.org/10.15554/pcij.11011976.76.93}, DOI={10.15554/pcij.11011976.76.93}, abstractNote={This paper describes the static and fatigue behavior of composite T-beams using a combination of prestressed concrete tension elements and reinforcing bars as the tension reinforcement. Static tests indicated similar behavior of two continuous beams, one being designed with moment redistribution at ultimate load and the other without moment redistribution. Repeated load tests were performed on six composite beams. Test results indicated that by augmenting multiple tension elements with steel reinforcing bars, the endurance limit of the composite beams was increased by nearly 43 percent. It was also shown that, under repeated load tests, the maximum crack width of the beam exclusively reinforced with tension elements was approximately one-half of that of the similar beam reinforced with conventional bars only.}, number={6}, journal={PCI Journal}, publisher={Precast/Prestressed Concrete Institute}, author={Zia, Paul and Mirza, J. F. and Rizkalla, S. H.}, year={1976}, month={Nov}, pages={76–93} }