Evaluation of residual performance of damaged RC frames considering their actual damage distribution: a methodology and a case study

Evaluating the residual performance of post-earthquake damaged buildings is crucial for making informed post-earthquake decisions. However, existing evaluation methods often struggle to capture the actual damage distribution, potentially leading to unreasonable results. In this study, a residual performance evaluation methodology for damaged RC frames based on the fiber beam-column model is proposed. The main feature is its ability to capture the actual distribution of seismic damage at both the structural and component levels. In the proposed methodology, the damage index of components within the structure is first quantified based on visual inspection. Then, the spatial distribution of damage to concrete and reinforcement steel within the components is quantified. Finally, using the quantified structural damage distribution, stress-strian curve for the damaged materials and a numerical model for the overall damaged structure are developed, which are then used for subsequent nonlinear dynamic/static analysis to assess the residual performance. The reliability of the proposed methodology is verified through its application to both a pseudo-static test and a shaking table test. The verification results show that the proposed methodolody accurately simulates the stiffness degradation of the test frames, and the quantified damage distribution effectively maps the actual damage phenomena, providing an explanation for the degradation mechanisms at the material level. Finally, the methodology is applied in a case study of a four-story RC frame building damaged in the Luding earthquake. The evaluation outcomes obtained in this study align with the expert assessments, while also accurately predicting the building's collapse safety under aftershocks.