Seismic fragility analysis and index evaluation of concrete-filled steel tube column frame-core tube structures

Abstract

To understand the effect of connection type on the seismic fragility of concrete-filled steel tube (CFST) column frame-core tube structures, typical structures with different numbers of storeys (15, 30, 45, and 60) and different types of beam-end connections (rigid connections, hinged connections, and rigid connections with outriggers) are designed. The probabilistic seismic demand models (PSDMs) of the structures are obtained using cloud analysis, and seismic fragility curves based on the mean period and the number of storeys are established. The results show that the differences in the seismic fragilities among the structures with the three types of connections can be effectively determined by the critical inter-storey drift ratio (IDR) and the storey ductility and that the determination method with the critical IDR is relatively simple. The use of beam-end hinges in the 15-storey structure results in an advantageous seismic performance, with a lower probability of exceeding the limit states, and the performance of the 60-storey structure with beam-end hinges is sensitive to spectral acceleration. The spectral acceleration and peak ground acceleration (PGA) can effectively describe the fragility curves based on the number of storeys and the mean period, respectively.

Keywords

• concrete-filled steel tube column frame-core tube structures
• seismic fragility
• connection type
• mean period
• number of storeys