Seismic vulnerability and resilience of steel-reinforced concrete (SRC) composite column buildings with non-seismic details

Abstract

Prior to the enforcement of seismic details, older-type fully encased steel-reinforced concrete composite (SCR) columns were utilized in many buildings and bridges constructed in active seismic regions worldwide. However, there is serious lack of knowledge in the literature about the seismic behavior of older buildings’ SRC composite columns with non-seismic details. Shear strength expressions, stiffness, backbone curves, nonlinear modeling parameters, and acceptance criteria for these columns are not available. A recent testing campaign (led by the first author) provided more test data to characterize the cyclic performance of SRC columns with non-seismic details. The current study has three primary objectives (1) suggesting some test-based nonlinear modeling parameters for SRC columns; (2) developing fragility, vulnerability and resilience functions for an older-type building with non-seismic details SRC columns; and (3) assessing ASCE 41-17 SRC column modeling recommendations by comparing prototype building performance, fragility, vulnerability and resilience functions obtained using test-based backbone curves and proposed nonlinear modeling parameters with those obtained using ASCE 41-17 SRC column criteria. The methodology used to establish economic vulnerability functions accounts for uncertainties in ground motion, structural response, damages and losses by means of Monte Carlo simulation techniques. The vulnerability functions for the structural, non-structural and content components of the prototype building are established. The results of this study demonstrate that the ASCE 41-17 criteria significantly underestimates the structural capacity and resilience and overestimates the seismic fragility and vulnerability of the system; however, this may not be surprising considering the implicit conservatism included in structural engineering standards. The study shows that the ASCE 41-17 modeling criteria overestimates collapse probability by 30–50% for moderate ground shaking and by 5–15% for intense ground shaking.