Seismic Vulnerability Analysis of Symbiosis of New-Built Structure and Historic Heritage Architecture Based on Incremental Dynamic Analysis

The historical heritage architecture—Red House is a brick masonry structure, which needs to be lifted as a whole and a new reinforced concrete frame structure built under it to cooperate with the protective comprehensive renovation project. In order to determine the seismic performance of this new and old symbiotic structure, this paper took the peak ground acceleration (PGA) as the ground motion intensity measure (IM), the maximum inter-story displacement ratio θmax as the structural damage measure (DM) for incremental dynamic analysis (IDA). The equivalent amplitude modulation method was used to modulate a series of original seismic waves, and then the nonlinear dynamic elastoplastic time history analysis was carried out through finite element simulation, and a series of IDA curves were obtained. On this basis, the seismic vulnerability analysis was carried out, and the damage probability in each limit state of the new and old symbiotic structure under different earthquake intensity was obtained. The results showed that the slightly damaged, moderately damaged, seriously damaged and collapsed probabilities under the 0.05 g PGA were 68.30, 18.14, 1.08 and 0.0018% respectively, meeting the design requirement of seismic fortification intensity equal to 6-degree. In addition, the finite element analysis results represented that the seismic damage mode of the new and old symbiotic structure was shown as the tensile damage of the new-built frame column bases and beam-column joints spreading upward to the tray beam, and finally penetrating the historical brick wall, causing structural failure.