Seismic collapse risk and performance factors assessment of RC dual lateral load-resisting system under far- and near-fault earthquake conditions

Abstract

This paper investigates the seismic collapse risk and performance factors of typical reinforced concrete (RC) buildings with a dual lateral load-resisting system, incorporating moment-resisting frames and shear walls, using the FEMA P-695 methodology. To achieve this, Six buildings, ranging from four to thirty stories, were designed in compliance with ASCE/SEI 7-16 and ACI 318-14 standards using the response spectrum method. Validated finite element models were developed in the OpenSees software to conduct nonlinear static and dynamic analyses, incorporating far- and near-field ground motion records as recommended by FEMA P-695. Key performance metrics, including maximum and residual inter-story drift ratios, collapse fragility curves, seismic performance factors, and collapse risk, were evaluated. The study revealed significant discrepancies between observed performance and current design standards for dual RC shear wall buildings. Notably, the overstrength factors for short-period and long-period performance groups (3.12 and 1.29 respectively) deviated from ASCE/SEI 7-16 standard values, with both overstrength and period-based ductility factors decreasing as building height increased. Despite adherence to ASCE/SEI 7-16 requirements, these buildings exhibited substantial collapse risks under both types of ground motion. Near-field conditions were particularly concerning, with collapse probabilities over a 50-year period ranging from 4.5% to 10.1%, significantly exceeding the 1% target. These findings highlight the need for refined seismic design approaches for RC shear wall buildings to improve performance across various seismic scenarios.