Seismic performance of RC frames with different column-to-beam flexural strength ratios under the excitation of pulse-like and non-pulse-like ground motion

摘要

The strong-column weak-beam (SCWB) design concept for RC frames has been adopted in many seismic design codes. However, seismic investigations show that the minimum column-to-beam flexural strength ratio (CBFSR) required in seismic codes usually cannot guarantee the SCWB failure mode of RC frames during strong earthquakes. This paper investigates the seismic performance of RC frames designed according to Chinese seismic codes with different CBFSRs by numerical simulations. The RC frames are subjected to near-field pulse-like and far-field non-pulse-like ground motions. The displacement responses and failure modes are analyzed. The results show that (1) larger CBFSR values are required to achieve the SCWB failure mode under the excitation of pulse-like ground motions than those under the excitation of non-pulse-like ground motions. (2) The uncertainties of the displacements decrease with increasing CBFSR and increase with increasing seismic intensity. The uncertainties of the displacements under the excitation of pulse-like ground motions are larger than those under the excitation of non-pulse-like ground motions. (3) With increasing CBFSR, the maximum interstory drift ratio (IDR) in the lower stories decreases, while the maximum IDR in the upper stories increases. Finally, recommended CBFSRs are proposed for achieving the SCWB failure mode with an 80% guarantee rate for different seismic hazard levels and ground motion characteristics.