@article{shahriar_gabr_montoya_ortiz_2023, title={Estimating live-bed local scour around bridge piers in cohesionless sediments: applicability and bias of selected models}, volume={60}, ISSN={["1208-6010"]}, url={http://dx.doi.org/10.1139/cgj-2022-0122}, DOI={10.1139/cgj-2022-0122}, abstractNote={ To design the foundation system of waterway bridges, Load and Resistance Factor Design guidelines suggest use of deterministic scour depth prediction models. Understanding the inherent bias of deterministic scour depth prediction models will advance the development of reliability index-based foundation design regime. Four bridge scour depth prediction models were assessed in terms of two statistical parameters, termed herein mean absolute percentage error (MAPE), and conservatism, percentage of cases the predicted scour depth exceeded the measured scour depth. Live-bed laboratory and field scour depth databases were used in analyses to quantify model scatter by comparatively assessing the computed scour depth versus measured data. For live-bed laboratory data, values of MAPE ranged from 23.5% to 59.8%, whereas conservatism ranged from 28.4% to 97.8%. For live-bed field data, conservatism varied from 93.3% to 95.1%, while MAPE ranged from 205.6% to 319%. Statistical models were applied to ascertain the biasness of the four deterministic models. Accuracy and conservatism of a given model were consequently adjusted through proposed modification factors. The proposed approach allows for the selection of a suitable modification factor to satisfy a target probability of deceedance or a target conservatism. }, number={4}, journal={CANADIAN GEOTECHNICAL JOURNAL}, publisher={Canadian Science Publishing}, author={Shahriar, Azmayeen R. and Gabr, Mohammed A. and Montoya, Brina M. and Ortiz, Alejandra C.}, year={2023}, month={Apr}, pages={471–487} }
 @article{shahriar_gabr_montoya_ortiz_2023, title={Framework for a reliability-based analysis of local scour and its effect on pile response in clay}, volume={153}, ISSN={0266-352X}, url={http://dx.doi.org/10.1016/j.compgeo.2022.105093}, DOI={10.1016/j.compgeo.2022.105093}, abstractNote={The analyses of axial and lateral capacity of a pile are significantly dependent on the appropriate estimation of scour depth, while the scour depth estimation procedure is uncertain due to the hydraulic, hydrologic, and geotechnical parameters uncertainty. Work herein is focused on developing a framework for reliability-based pier scour assessment methodology and demonstrate its integration with the concept of Load and Resistance Factor Design (LRFD) approach. Scour factors are proposed based on reliability level ( β ) and the associated probability of deceedance (POD). Three example applications of axially and laterally loaded pile design approach while including scour factor in the LRFD framework are demonstrated. Based on axial pile capacity analysis, the increase of pile length when the β -based scour assessment is used with the soil resistance factors, was estimated to be 26.5–29.6 % higher compared to using the deterministic scour with soil resistance factor. In the case of lateral pile response analysis, as β is increased from 2.0 to 3.0, the lateral pile head deflection increased by 46–132 % compared to the deterministically-estimated scour depth case. To obtain β = 3.0 for the considered example while maintaining the pile length unchanged, the pile diameter needed to be increased by 35.7 % compared to the base case pile’s diameter.}, journal={Computers and Geotechnics}, publisher={Elsevier BV}, author={Shahriar, Azmayeen R. and Gabr, Mohammed A. and Montoya, Brina M. and Ortiz, Alejandra C.}, year={2023}, month={Jan}, pages={105093} }
 @article{shahriar_gabr_montoya_ortiz_2023, title={Local scour around bridge abutments: Assessment of accuracy and conservatism}, volume={619}, ISSN={["1879-2707"]}, url={https://doi.org/10.1016/j.jhydrol.2023.129280}, DOI={10.1016/j.jhydrol.2023.129280}, abstractNote={More than 80 percent of the bridges in the United States are built over waterways. The support systems of the structures crossing waterways are subjected to scour during their service life owing to the flowing water-induced bed shear stresses, resulting in scour. Work herein is focused on characterizing the error associated with three abutment scour prediction models included in the Hydraulic Engineering Circular No. 18. An abutment scour database is utilized to quantify the predicted versus the measured scour depth relationship. Abutment scour prediction models are assessed in terms of two statistical parameters, termed herein Mean Absolute Percentage Error (MAPE, as a measure of accuracy of the prediction), and Level of conservatism, (defined as percentage of cases for which the predicted scour exceeded the measured scour.) For scour associated with vertical wall and spill through abutments, responses to long abutment, and intermediate abutment are examined separately. For vertical wall abutments, conservatism ranged from 4.76% to 100%, and MAPE ranged from 44% to 201%. For spill through abutments, conservatism ranged from 0% to 100%, and MAPE ranged from 10.3% to 347%. Comprehension of the accuracy and conservatism of the deterministic models considered herein contributes to understanding the limitation of the scour depth prediction models.}, journal={JOURNAL OF HYDROLOGY}, author={Shahriar, Azmayeen R. and Gabr, Mohammed A. and Montoya, Brina M. and Ortiz, Alejandra C.}, year={2023}, month={Apr} }
 @article{shahriar_ortiz_montoya_gabr_2021, title={Bridge Pier Scour: An overview of factors affecting the phenomenon and comparative evaluation of selected models}, volume={28}, ISSN={2214-3912}, url={http://dx.doi.org/10.1016/j.trgeo.2021.100549}, DOI={10.1016/j.trgeo.2021.100549}, abstractNote={Scour, defined by the loss of geomaterials surrounding a foundation support system, is a primary cause of bridge failure in the United States and worldwide. Work herein presents a comprehensive review of the current state of knowledge on geotechnical aspects of erodibility, factors influencing pier scour, factors complicating pier scour assessment, and databases available on erodibility and pier scour. A summary of deterministic pier scour models, developed since 1990, is presented in view of the factors affecting scour rate and equilibrium magnitude. The study discusses challenges in the predictive approaches reviewed in the paper. In addition, advancements in probabilistic pier scour models, and observation-based models are summarized. Four pier scour models, namely Wilson (1995) model, Melville (1997) model, Hydraulic Engineering Circular No. 18 (2012) model, and Briaud (2014) model are comparatively applied to data from laboratory pier scour database. Error statistics and accuracy, precision, and probabilistic distribution of predictions from these models are presented and discussed.}, journal={Transportation Geotechnics}, publisher={Elsevier BV}, author={Shahriar, Azmayeen R. and Ortiz, Alejandra C. and Montoya, Brina M. and Gabr, Mohammed A.}, year={2021}, month={May}, pages={100549} }
 @article{elahi_shahriar_islam_2021, title={Engineering characteristics of compressed earth blocks stabilized with cement and fly ash}, volume={277}, ISSN={["1879-0526"]}, DOI={10.1016/j.conbuildmat.2021.122367}, abstractNote={Fly ash is a common industrial waste that requires a proper disposal which otherwise will have a detrimental effect on the environment. As such, utilization of fly ash in producing Compressed Stabilized Earth Blocks (CSEB) can provide suitable means to promote sustainability. Work herein focuses on investigating the performance of CSEBs stabilized with cement and fly ash (FA) as an alternative to traditional construction materials, like Fired Clay Bricks (FCB). Strength characteristics of CSEBs have been evaluated in terms of compressive, split tensile, flexural and shear strength. For durability, accumulated loss of mass due to cyclic drying-wetting test, wet strengths, submersion and efflorescence test have been performed. For this study, 270 CSEBs and 192 cylindrical samples are prepared with 0–10% cement and 0–30% FA (All the percentages are by dry mass of soil taken). Addition of 10–30% FA along with cement increases the compressive strength, flexural strength and split tensile strength by different magnitudes depending on the cement content used. Inclusion of FA ≥ 20% with 5% and 7% cement satisfies the strength criterion suggested by different standards. Moreover, FA was effective in reducing the cement content in the mix without sacrificing the strength. Cyclic drying-wetting test shows that with the increase of the amount of FA with cement, accumulated loss of mass reduces, which is in agreement with the observation of microstructural analyses. Strength retention of the samples after cyclic drying-wetting test ranged within 51–88%, showing the durable performance of cement-FA stabilized earth. Results of triaxial test indicate that FA improves the peak deviatoric stress-strain and failure stress-strain irrespective of cement content and confining stress. With the addition of 0–30% FA with 5% and 7% cement, the cohesion parameter varies within 159–315 kPa, and the angle of internal friction varies within 38.1–57.1°, indicating an improved shear response of cement-FA stabilized mixes. Life Cycle Analysis (LCA) shows that considering energy consumption, Global Warming Potential (GWP) and other environmental impacts, CSEBs are superior to the traditional FCBs.}, journal={CONSTRUCTION AND BUILDING MATERIALS}, author={Elahi, Tausif E. and Shahriar, Azmayeen Rafat and Islam, Mohammad Shariful}, year={2021}, month={Mar} }
 @article{elahi_shahriar_alam_abedin_2021, title={Engineering characteristics of soil stabilised with saw dust ash and cement}, volume={9}, ISSN={["1748-6033"]}, DOI={10.1080/17486025.2021.1981464}, abstractNote={ABSTRACT The study herein investigates the performance of Saw Dust Ash (SDA) in combination with cement for soil stabilisation. Performance of SDA is studied with respect to compressive strength, shear strength, penetration and deformation responses. For a certain cement content, the compressive strength reaches a maximum value with the increase of SDA and the corresponding SDA content is defined as the optimum content. Optimum SDA content varies within 6–12% based on the percent of cement added. When optimum amount of SDA is added, 28 days’ compressive strength of 2406–5625 kPa was achieved for varying amount of cement (3–7%). The mechanical response is illustrated using microstructural observations. Results from direct shear tests revealed that with the inclusion of 6–15% SDA with cement, improved shear strength parameters (cohesion, angle of internal friction) can be obtained; an angle of internal friction as high as 40 was achieved herein. Compression index can be reduced by 32–41% compared to unstabilised soil if optimum amount of SDA-cement is added. It is concluded that considering compressive strength, shear strength, penetration resistance and compressibility, SDA can effectively be used along with cement for stabilisation of clay soil.}, journal={GEOMECHANICS AND GEOENGINEERING-AN INTERNATIONAL JOURNAL}, author={Elahi, Tausif E. and Shahriar, Azmayeen Rafat and Alam, Md Kausar and Abedin, Md Zoynul}, year={2021}, month={Sep} }
 @article{shahriar_montoya_ortiz_gabr_2021, title={Quantifying probability of deceedance estimates of clear water local scour around bridge piers}, volume={597}, ISSN={0022-1694}, url={http://dx.doi.org/10.1016/j.jhydrol.2021.126177}, DOI={10.1016/j.jhydrol.2021.126177}, abstractNote={Local bridge scour, which is defined as the loss of soil particles/mass surrounding a pier foundation due to the flowing water-induced shear stresses, is a primary cause of bridge failure in the United States and worldwide. Current practice of bridge scour prediction is mostly based on the use of deterministic models. Work herein presents statistical models that extend five deterministic approaches reported in literature to predict the expected scour depth while quantifying inherent model bias and uncertainty in view of data scatter. Clear water scour database is used herein and the analyses quantify model scatter by comparatively assessing the computed scour depth versus measured data reported in the database. A relationship between probability of deceedance associated with the predicted scour depth and a modification factor (that is applied into the deterministic prediction) is devised. The modification factor allows for the use of the scour magnitude computed from the deterministic models while quantifying the probability of a computed scour depth being less than or more than a most likely value (per measurements reported in the database). The application of the proposed model is demonstrated with an example and the results are discussed.}, journal={Journal of Hydrology}, publisher={Elsevier BV}, author={Shahriar, Azmayeen R. and Montoya, Brina M. and Ortiz, Alejandra C. and Gabr, Mohammed A.}, year={2021}, month={Jun}, pages={126177} }
 @article{islam_elahi_shahriar_mumtaz_2020, title={Effectiveness of fly ash and cement for compressed stabilized earth block construction}, volume={255}, ISSN={["1879-0526"]}, DOI={10.1016/j.conbuildmat.2020.119392}, abstractNote={For saving natural resources, reducing pollution and increasing energy efficiency, Compressed Stabilized Earth Block (CSEB) can serve as a suitable alternative to conventional Fired Clay Brick (FCB). In this study, suitability of industrial waste, Fly Ash (FA) is assessed along with cement as stabilizers for producing CSEBs with coarse grained soil. Different combination of cement and FA (5–10% cement and 5–25% FA; by weight of dry soil) was considered to prepare CSEBs for finding the optimum mix composition in terms of strength, durability, deformation characteristics and cost effectiveness. Furthermore, strength and durability test results are compared to the design criteria reported in Indian Standard, Sri Lankan Standard, Standard Australia, British Standard and Malaysian Standard for assessing its viability as construction material. With the increase in cement content, strength of the blocks gradually increases; however, at a definite cement content, addition of FA increases strength up to a certain limit and then begins to drop. Inclusion of 7–8% cement and 15–20% FA is found to provide adequate dry compressive strength (>5 MPa), wet-to-dry compressive strength (>0.33) and enough durability in terms of water absorption (<20%) as recommended by British Standard and Standards Australia. The behavior of the CSEBs were also analyzed through microstructural investigation, where SEM images were taken to ascertain the morphologic and anatomic changes that occurred at different fly ash contents. At a definite cement content, with the increase of FA, peak strain and failure strain increase; thereby indicating an improved straining capacity of the blocks due to inclusion of FA. Moreover, modulus of elasticity improves with increasing amount of cement and FA for both dry and wet state. Furthermore, economic analysis of a typical house constructed with CSEBs and FCBs was performed and compared with literature. Considering all the parameters it can be concluded that CSEBs prepared with cement and fly ash as stabilizers can be used as a sustainable construction material.}, journal={CONSTRUCTION AND BUILDING MATERIALS}, author={Islam, Mohammad Shariful and Elahi, Tausif E. and Shahriar, Azmayeen Rafat and Mumtaz, Nashid}, year={2020}, month={Sep} }
 @article{elahi_shahriar_alam_abedin_2020, title={Effectiveness of saw dust ash and cement for fabrication of compressed stabilized earth blocks}, volume={259}, ISSN={["1879-0526"]}, DOI={10.1016/j.conbuildmat.2020.120568}, abstractNote={This study focuses on investigating the effectiveness of Saw Dust Ash (SDA) and cement for fabricating strong and durable Compressed Stabilized Earth Block (CSEB) using coarse-grained soil. CSEB is a viable alternative to traditional Fired Clay Brick (FCB) as warranted by reduced associated pollution and increased energy efficiency. Four different cement contents (4%, 6%, 8% and 10%) and different SDA contents (0–10%) are considered to discern optimum combination to fabricate satisfactory CSEB in terms of compressive strength, shear strength, deformation behavior and durability. For a particular cement content, addition of SDA increases the compressive strength gradually, reaches a maximum value which is identified as optimum content and thereafter begins to drop. Optimum amount of SDA was found 4% for 4% cement, 6% for 6–8% cement and 8% for 10% cement. Addition of cement-SDA is found to increase the compressive strength of the blocks by 21–147% compared to that of unstabilized earth blocks. Moreover, optimum combination of cement-SDA provides CSEBs with maximum density and minimum porosity. Inclusion of cement-SDA is found effective in increasing angle of internal friction, ϕ of the stabilized mix. With addition of optimum SDA (4–8%) with cement, mixtures were found to exhibit ϕ>58o. CSEBs with optimum amount of cement-SDA is found to provide maximum modulus of elasticity, peak strain and failure strain. Addition of 6–8% SDA with 6–10% cement is found durable in terms of water absorption (<15%), wet compressive strength (>700 kPa) and wet-to-dry strength ratio (>0.33). Based on all the parameters and obtained test results, it can be concluded that cement-SDA stabilized earth blocks can be efficiently considered as a suitable construction material.}, journal={CONSTRUCTION AND BUILDING MATERIALS}, author={Elahi, Tausif E. and Shahriar, Azmayeen Rafat and Alam, Md Kausar and Abedin, Md Zoynul}, year={2020}, month={Oct} }
 @article{islam_tausif-e-elahi_shahriar_nahar_hossain_2020, title={Strength and Durability Characteristics of Cement-Sand Stabilized Earth Blocks}, volume={32}, ISSN={["1943-5533"]}, DOI={10.1061/(ASCE)MT.1943-5533.0003176}, abstractNote={AbstractConventional building materials like fired clay brick (FCB) and concrete blocks are expensive and, in some cases, have detrimental effect on environment. Compressed stabilized earth block (...}, number={5}, journal={JOURNAL OF MATERIALS IN CIVIL ENGINEERING}, author={Islam, Mohammad Shariful and Tausif-E-Elahi and Shahriar, Azmayeen Rafat and Nahar, Kamrun and Hossain, Tahsin Reza}, year={2020}, month={May} }
 @article{elahi_shahriar_islam_mehzabin_mumtaz_2020, title={Suitability of fly ash and cement for fabrication of compressed stabilized earth blocks}, volume={263}, ISSN={["1879-0526"]}, DOI={10.1016/j.conbuildmat.2020.120935}, abstractNote={This study is aimed at utilizing industrial waste Fly ash (FA) in combination with cement for production of environment friendly and economically viable Compressed Stabilized Earth Blocks (CSEBs). CSEBs are prepared with four cement contents (4%, 6%, 8% and 10%) and four FA contents (0%, 10%, 20%, 30%) and its performance are assessed in terms of strength and durability. Strength was measured using unconfined compression test, and consolidated undrained (CU) triaxial test; and durability was assessed in terms of water absorption test, wet compressive strength test, and accumulated loss of mass (ALM). Unconfined compression test shows that with the increase of cement, strength of the blocks increases for a definite FA content, however, for a fixed amount of cement, strength increases with addition of certain amount of FA, which is defined as the optimum FA content beyond which strength begins to drop. For 4% and 6% cement, optimum FA content was found 10%, for 8% cement, 20% FA was found to be the optimum content, whereas for 10% cement the optimum FA content is 30%. Deformation characteristics of CSEBs with different cement-FA combinations are analyzed in terms of stress-strain response and modulus of elasticity. Addition of proper amount of FA is found to improve modulus of elasticity, peak and failure strain response for a definite cement content. Moreover, microstructural investigation is carried out to investigate the arrangement of soil matrix for different contents of stabilizers. Optimum content of cement-FA obtained from unconfined compressive strength provide wet-to-dry strength ratio >0.33 which is an indicator of better durability performance. CU triaxial test results show that at a confining stress of 200 kPa and 300 kPa, maximum stress ratio and secant modulus occurs at a mix composition of 8% cement and 20% fly ash, which was considered optimum from compressive strength test scheme. Finally, test results were compared with the specifications of various existing standards and it can be concluded that with addition of optimum amount of cement-FA, CSEBs with acceptable strength and durability response can be produced.}, journal={CONSTRUCTION AND BUILDING MATERIALS}, author={Elahi, Tausif E. and Shahriar, Azmayeen Rafat and Islam, Mohammad Shariful and Mehzabin, Farzana and Mumtaz, Nashid}, year={2020}, month={Dec} }