Fragility Analysis of Prefabricated RCS Hybrid Frame Structures Based on IDA

The prefabricated reinforced concrete columns–steel girder (RCS) hybrid frame structure using column–column connections is a kind of green and environmentally friendly building structure; its seismic performance is investigated. The seismic susceptibility and key influencing factors are systematically evaluated through the establishment of an analytical model and incremental dynamic analysis (IDA) method. A typical three-span, six-story prefabricated RCS hybrid frame structure is designed and numerically modeled with good agreement with the test data. Sa(T1,5%) and PGA double ground motion intensity parameters are selected for IDA analysis. A comparison between the quantile curve method and the conditional logarithmic standard deviation method reveals that using Sa(T1, 5%) as the intensity measure (IM) provides greater reliability for analyzing the vulnerability of the prefabricated RCS hybrid frame structure. The seismic probability demand model of the structure is fitted with Sa(T1,5%) as a parameter and the seismic fragility curves of the structure are plotted; this shows that the slope of the seismic fragility curves becomes smaller after the structure enters the elastic–plastic state, and exhibits good seismic performance. By studying the effects of concrete strength, longitudinal reinforcement strength, and the axial compression ratio on the seismic fragility, it can be seen that with the increase in concrete strength and longitudinal reinforcement strength, and the decrease in axial compression ratio, the overall ductility of the structure increases, the resistance to lateral deformation of the RCS hybrid frame structure is enhanced, and the seismic performance of the prefabricated structure is improved.