Mapping structural damage to material damage for analysis of urban buildings considering actual damage states

Predicting the residual performance of reinforced concrete (RC) buildings under specific damage states is crucial for structural recovery and retrofitting. To assess the seismic capacity of damaged buildings, this paper proposes a model updating method that considers actual damage states. Specifically, a numerical simulation method for damaged RC structures was developed based on OpenSEES, along with a material parameter updating framework for damaged RC components. A database of 22 RC columns characterized by flexural failure was established to develop a damage distribution model (DDM) for determining the constitutive relationships of damaged materials. Considering the discrete distribution of material damage across the component section, three DDMs based on fractile curves were proposed: DDM-16th, DDM-50th, and DDM-84th. Comparisons between simulation and experimental results of 6 RC column specimens show that the model based on DDM-50th accurately predicts residual performance, with errors in strength, stiffness, and energy dissipation all within 10 %. DDM-16th and DDM-84th are recommended for estimating the upper and lower limits of seismic capacity for damaged RC buildings to obtain a comprehensive assessment. Finally, the proposed model updating method was applied to a 5story, 4-bay frame, and seismic fragility analyses were conducted on undamaged and damaged frames. Results indicate that damage significantly reduces the seismic performance of RC structures, with performance degradation becoming more pronounced at higher limit states. The present study provides a reference for post-earthquake recovery or reconstruction of RC structures.