@article{martinez_kowalsky_2023, title={Influence of Viscous Damping Models on the Inelastic Response of Reinforced Concrete Columns and Bridges}, volume={149}, ISSN={["1943-541X"]}, DOI={10.1061/JSENDH.STENG-11040}, abstractNote={The appropriate estimation of displacements is crucial in performance-based design. Among the options to assess deformation demands, Nonlinear Time History Analysis (NLTHA) is the most sophisticated. However, previous research has shown that NLTHA is sensitive to the viscous damping model definition, and there is substantial disagreement in the engineering community regarding damping model choices. Thus, the goal of this paper is to show the impact of viscous damping model assumptions on the nonlinear response of bridges. A displacement sensitivity study was conducted on several multi-span bridges using various viscous damping models and earthquake records. The results indicate that the mean displacement varies as a function of the displacement ductility level and damping model. In order of ascending displacement demand, the Wilson-Penzien model had the lowest demands followed by the Rayleigh-Initial stiffness, Mass proportional, Rayleigh-Tangent stiffness, Tangent stiffness proportional damping, and Zero-damping. Also, this paper proposes a new viscous damping model. We expect these findings to help practitioners understand the implications of the choice of the damping model and guide the analyst when selecting damping parameters.}, number={2}, journal={JOURNAL OF STRUCTURAL ENGINEERING}, author={Martinez, Diego R. and Kowalsky, Mervyn J.}, year={2023}, month={Feb} }
 @article{martinez_kowalsky_2023, title={Nonlinear seismic performance of RC bridges using the ESA, EDA, DDBA, and nonlinear analysis with various viscous damping models}, volume={39}, ISSN={["1944-8201"]}, DOI={10.1177/87552930221145435}, abstractNote={ Modern bridge seismic design follows a performance-based seismic design (PBSD) philosophy where the structure is designed to achieve a prescribed limit state under a defined hazard. Nevertheless, the demands may substantially diverge depending on the PBSD method applied in the assessment. This article presents a demand sensitivity analysis using the elastic (ESA) and dynamic (EDA) procedures of the AASHTO Seismic Guide Specifications and direct displacement-based assessment (DDBA). The investigation was conducted using 81 reinforced concrete (RC) bridges and ten multi-period spectra from a shallow tectonic regime. Moreover, these demands were compared with nonlinear time history analysis (NLTHA) using five viscous damping models. Seven compatible records were employed to calculate the envelopes of transverse displaced shapes and cumulative distribution functions of the column with the highest displacement ductility. These average inelastic responses were contrasted with the predictions from the ESA, EDA, and DDBA. For regular bridges, this study found that the elastic procedures considerably underestimate the deformations, while DDBA compares well with NLTHA, especially for high ductility levels. Also, a discussion about the impact of the viscous damping models is included. We expect these findings may encourage practitioners to use DDBA as a reliable alternative to evaluate the seismic performance of RC bridges. }, number={1}, journal={EARTHQUAKE SPECTRA}, author={Martinez, Diego R. and Kowalsky, Mervyn J.}, year={2023}, month={Feb}, pages={242–268} }