Prediction of fragility deterioration of earthquake-damaged RC structure based on damaged section analysis

Abstract

Evaluating quantitatively the performance of earthquake-damaged structures is significant for facilitating post-earthquake reconstruction. However, it is difficult to quantitatively assess the effect of earthquake-induced damage on structural performance. In this paper, a new method to establish the earthquake-damaged structure model (EDSM) based on the damaged section analysis (DSA) procedure is proposed. DSA can consider the effect of the seismic damage on material properties and sectional dimensions, which are the primary difference between DSA and classical moment-curvature analysis. Furthermore, the DSA is verified on two RC columns by the comparison of hysteretic curve between damaged column models and test columns under cyclic loadings. The EDSM is established by replacing the plastic hinge regions of the damaged components with “Hysteretic” material. This method is applied to a RC frame structure and is verified for different ground motions with various intensities. Moreover, by the comparison of vulnerability curves between undamaged structure model (UDSM) and EDSM, the vulnerability of EDSM regarding the moderate limit state is more fragile than the vulnerability of UDSM regarding the slight limit state. A reduction index is proposed to quantitatively evaluate the deterioration of seismic performance of EDSM. It can be identified that the reduction in vulnerability decreases gradually as the limit state increases, which shows the earthquake-induced damage has a more significant effect on the elastic properties of structure.