Component damage-based seismic fragility analysis of high-rise building with transfer structure

Fragility analysis is an effective tool used to assess the seismic risk of high-rise buildings. During the process of fragility analysis, determining the engineering demand parameters (EDPs) corresponding to different damage states is of great importance as they directly influence the fragility results. However, for buildings with transfer structures, the EDPs corresponding to different damage levels are difficult to determine since the maximum demand in such buildings is mostly concentrated at the level of irregularity. Obtaining the fragility curves at component level (as used for bridge structures) may provide new insight into the seismic fragility analysis of buildings with transfer structures. Due to differences in structural systems and seismic response, it may be questionable whether such an approach can be directly applied to the fragility analysis of high-rise buildings. In view of this, a component damage-based approach suitable for high-rise buildings and a detailed framework through which to obtain the fragility curves are proposed in this study. This method was applied to assess the seismic risk of a 34-story concrete building with a transfer plate. The damage states for various structural components were obtained through a damage index (DI) model. The relationship between the DIs of the components and the maximum inter-story drift ratios (MIDRs) was generated by cloud analysis, and MIDRs corresponding to different component damage states were obtained. The fragility curves at both component and system levels were evaluated. Numerical results indicate that, at the conservative level of PGA (0.2 g), the probability that the main components of the building incur irreparable damage is small, and the performance-based seismic design requirements can be met.