STUDY ON DESIGN METHOD OF STRONG COLUMN AND WEAK BEAM BASED ON FRAGILITY FOR PRESTRESSED CONCRETEFRAME STRUCTURES

According to the related researches and analyzes of earthquake damage, the RC frame structure designed by current standard is difficult to achieve strong column-weak beam mechanism. The Chinese specification for aseismic design of PC structures (04) based on the aseismic code (01) lags behind the aseismic code (10). The study on PC strong column-weak beam mechanism is necessary. Firstly, a new method that MAFC (the moment amplification factor of column ends) for each aseismic level of PC frame structure was adjusted according to the actual beam ends bending capacity. Secondly, to define the reasonable value of MAFC, four multi-layer PC frame structures at 1st, 2nd and 3rd anti-seismic grade were designed according to the aseismic design of PC structures (04). 4 nonlinear analysis models were established in OpenSees, which implies that the stress of longitudinal bars of columns end sections except the first floor is below the yield stress under strong earthquake excitation. 35 seismic waves were selected for each frame to analyze the earthquake response, and the statistical analyses of MAFC demand were carried out. The results show that the PC frame MAFC for interior and exterior joints are 1.05 and 1.0 respectively at 3rd anti-seismic grade, 1.25 and 1.15 respectively at 2nd anti-seismic grade, 1.3 and 1.2 respectively at 1st anti-seismic grade. Finally, two PC frame structures were redesigned according to the new method to verify the practicability of the new design method and MAFC by IDA-based vulnerability analysis.