BEHAVIOR OF REINFORCED CONCRETE SHEAR WALLS UNDER EFFECT OF REPEATED EARTHQUAKES

Abstract

Current seismic design practices are based on a multi-level design approach at which design of buildings is done to satisfy certain performance criteria (e.g. serviceability, damageability, and collapse prevention) under the effect of a single isolated earthquake with a specific return period. Although failure cases of several buildings have been reported due to multiple earthquakes, these practices don't give any attention to the deteriorative effects of prior shakings. They only focus on structures' vulnerability under the targeted earthquake. Hence, the safety of the structure may be inappropriate under the subsequent earthquakes, which may be smaller than the design earthquake. Throughout this study, a comprehensive literature review was conducted to discuss the previous studies' modeling assumptions, types of the selected seismic sequences, shortcomings, and results. Analytical models were generated to simulate the behavior of Reinforced Concrete (R.C.) structural walls exposed to quasi-static cyclic and time-history lateral loading. OpenSees platform was used to develop the analytical models, while Response-2000 software was used to extract the wall sectional shear behavior to aggregate it back into the OpenSees fiber element. It was found that the modeling approach could simulate the experimentally measured wall behavior with an acceptable degree of accuracy, and it could represent the different degrading features in both concrete and reinforcing bars. Modeling capabilities were assessed, and recommendations for governing factors were given for modeling R.C. structural walls using force-based element in OpenSees. A parametric study was conducted using the calibrated models to assess the response of R.C. shear walls under the effect of repeated earthquakes. The study focused on the effect of the first-shock amplitude, and its degree of damage, and the type of earthquake sequence either real or artificial, on the inelastic response of the structure.