An improved response surface method for fragility analysis of base-isolated structures considering the correlation of seismic demands on structural components

An improved response surface method (RSM) for the seismic fragility analysis of base-isolated structures is proposed so that the correlation of seismic demands on the structural components can be effectively considered. In addition, the performance levels of base-isolated structure as well as the associated quantitative indices for various structural components are discussed and defined. Taking a typical base-isolated reinforced concrete plane frame with lead-rubber-bearings as an illustrative example, the seismic fragility analysis following the computational procedure based on the improved RSM are conducted. Through the illustrative example, it is demonstrated that the obtained response surface models for the seismic demands on the components as well as the correlation of components are accurate and reliable; moreover, the computational cost for the system seismic fragility analysis is significantly reduced due to the use of Monte Carlo simulation; finally, it is indicated that it is necessary to take into account the correlation of components in order to obtain more accurate system fragility curves of base-isolated structure.