INFLUENCE OF NEAR-FAULT VELOCITY PULSE ON THE SEISMIC RESPONSE OF REINFORCED CONCRETE FRAME

Under the condition of acceleration response spectrum being consistent, the engineering properties of near-fault velocity pulse are studied. Firstly, two groups of ground motions that have same response spectra are generated; the first one contains field recorded seismograms with distinct velocity pulses while the other contains the simulated ground motion time histories synthesized with the response spectra of the ground motions in the first group as target spectra. During synthesizing, these ground motions can be generated to contain no velocity pulses by using the method of superimposing narrow-band time-histories to control the velocity peaks. And then, the differences were analyzed between the dynamic responses of reinforced concrete frames excited by these two kinds of ground motions, and the influences of velocity pulse on the seismic responses, especially the elastic-plastic seismic responses, of structures are studied with the response spectra being the same. The results show that in terms of some structural dynamic response parameters, such as the storey shear force, the inter-storey displacement, and the storey maximum displacement et al., the structural responses to the ground motion with velocity pulse are increased by considerable magnitudes when the seismic responses of structures step into the elastic-plastic stage, compared with the ground motion without velocity pulse, although the spectral accelerations of the two groups of input ground motions are the same. Under such circumstance, the response spectrum cannot fully reflect the influence of velocity pulse on the seismic responses of structure.