Seismic Performance and Vulnerability Assessment of Fully Bolted Prefabricated Frames Consisting of CFST Composite Columns and PEC Beams

Partially encased concrete （PEC） composite beams and concrete-encased concrete-filled steel tube（CFST） composite columns both exhibite high bearing capacity， excellent ductility， and superior fire resistance，and the use of all-bolts for the connection can effectively utilize the excellent performance of the two components and avoid the disadvantages of the commonly used welded node zone such as the difficult construction and the large welding workload. In this paper， a fully bolted prefabricated frame structure consisting of CFST composite columns and PEC beams was proposed. Based on the component method， considering the diffusion mechanisms of tension and pressure in outer concrete， the bearing capacity and stiffness design methods for all bolted joint were established. An elastoplastic analysis model for the prefabricated frame structure was established using OpenSEES， and its accuracy and rationality were verified through test results. Time-history analysis was performed on the prefabricated CFST composite column frame structure， demonstrating that the frame structure exhibited favorable seismic performance and meets the current code requirements. In addition， the fragility of the assembled frame structure was analyzed， and the results show that the collapse resistance of this type of frame structure meets the requirements of the code.