Resertch On Near-field Sesismic Collapse Capacity Of Inverted-V CBSF Based On Energy-based Sesismic Design Method

In order to improve the anti-collapse performance of the structures,many researchers have proposed various performance-based seismic design methodologies which were based on performance and energy dissipation capacity of the structures.Song Bin[1] has proposed the energy seismic design of Chevron concentrically braced steel frames under the near-field earthquake which was based on the MECE spectrum,and provided two examples.But this design method has not proved to be credible,the seismic collapse-resistant capacity and the probability of collapse of the structures which were designed by that method is need to be studied.In order to assess the energy-based seismic design method which was mentioned in the literature [1],this paper analyzed the earthquake resistant capability and the seismic fragility of the structures.In this paper,the status of the research about the seismic anti-collapse capacity,the principle of the collapse margin ratio and the steps of the incremental dynamic analysis(IDA)were introduced.According to the test data of the Chevron concentrically braced steel frames,the structural collapse judgment index has been put forward.According to the seismic collapse assessment system in FEMAP695 and the database of the real ground motion records,the IDA method was used to calculate the collapse margin ratio(CMR)and the fragility curves of the two structures.At the same time,according to the position of the weak-layer of the structures,the improvement ideas about how to optimize the structure collapse mode were given.The results show that the structures,designed by the energy seismic design of Chevron concentrically braced steel frames under the near-field earthquake method,have enough anti-collapse capacity and the probability of collapse all can meet the requirements of the FEMAP695.It means that the design method is credible.The two structures designed by the same way,but their CMR and the probability of collapse are different by the height,that means the design method could be optimized more rational and efficient.