Characteristic Research On Near-field Earthquake And Seismic Response Analysis Of High-rise Buildings

Recently, both foreign and domestic scholars have researched extensively aboutnear-field earthquake. But they mainly focus the study on magnitude, site category,fault distance and focal mechanism etc. The ratio of peak velocity (PGV) and peakacceleration (PGA) is rarely involved. By far, the definition of near-field earthquake isstill not unified，the influence of the ratio of PGV/PGA on high-rise buildingstructures is rarely being researched either. According to these issues, this thesisinvolves the following work:Firstly, The characteristics of near-field ground motions are researched anddiscussed; then the analysis methods of Seismic on high-rise building are studied; Andlater all kinds of response spectrum are analyzed too.Based on the data of608groups (aggregately1216seismic wave rays) ofnear-field earthquake records，the effects of PGV/PGA ratio and site category on thecharacteristics of near filed earthquake ground motions are analyzed. The results showthat:(1) the PGV/PGA ratio has a great impact on all kinds of response spectrum.Among them, the width of sensitive area of the acceleration response spectrum widensand the attenuation rate of the descent stage slows down with the increase of thePGV/PGA ratio. The velocity response spectrum and displacement response spectrumtend to rise within the whole cycle, and the larger the ratio, the faster they rise.(2)Generally speaking, site category has little effect on the response spectrum. Thegeneral tendency is: the softer of the sites, the wider of the stage in sensitive area ofthe acceleration response spectrum and the slower of the attenuation rate on thedescent stage. within the whole cycle, velocity spectrum and displacement spectrumcurves tend to gradually rise.With the method of linear time history analysis，the behavior of one ten-storyreinforced concrete frame is studied under the action of near-field ground motions.The results show that:(1) the influence of the PGV/PGA ratio magnitude for theresponses of10-story framework is obvious: the larger is the ratio, the greater are thebase shear, top displacement and inter-story displacement angle. When the ratioexceeds0.3s, the inter-story displacement angle will exceed the limits set by theregulation and stipulation. That is to say, be unsafe,(2) peak velocity, peakacceleration and the fault distance have little influence on the structure. Statisticalresults indicate: the base shear, top displacement and inter-story displacement angle ofthe structure decrease with the increase of peak acceleration, and become larger with the increase of peak velocity. When the fault distance get larger, the base shear, topdisplacement and inter-story displacement angle increase firstly and then tend todecrease.