SEISMIC FRAGILITY ANALYSIS OF MULTI-STOREY PC FRAME STRUCTURES USING INCREMENTAL DYNAMIC ANALYSIS

To investigate the rationality of the engineering design parameters, that is, axial compression ratio and moment magnifying coefficients at column ends, etc., specified in the current code for seismic design of prestressed concrete structures (JGJ140-2004), six seismic grade for secondary bonded PCF are designed with various axial compression ratios and moment magnifying coefficients at column ends according to the current code. In addition, with the consideration of randomness in material, loads and the ground motion, the corresponding models based on nonlinear fiber beam-column finite element are established in Opensees. Finally, on the basis of incremental dynamic analysis, the seismic fragility analysis is performed for each model, respectively. The results indicate that: whether increasing the moment magnifying coefficients at column ends while keeping the axial compression ratio invariant or decreasing the axial compression ratio while keeping the moment magnifying coefficients at column ends unchanged, both of which has a positive impact on the structural seismic performance. Hence, suggestions were proposed in the revision of code for aseismic design of prestressed concrete structures that the moment magnifying coefficients at column ends should be improved appropriately (greater than 2.0), and the limitations on axial compression ratio should be stricter (less than 0.7).