Numerical Simulation Of Response Spectrum For Long-period Ground Motions With Shaking Table Test

With the economic development in our country, more and more high-rise buildings and large span buildings will be springing up. Natural vibration period of most buildings were long, which of some Constructions even beyond the range of the design response spectrums of Chinese seismic design code. More long-periodic structure would be built, and Seismic requirements for them would be higher. At present, structural seismic action found mainly through the design response spectrums of code. While the researches show that the long-period segment in the seismic influence coefficient response spectrum of China code had higher value.Most of these researchesused the theoretical method, while few adopted experimental methods. The methods used in this paper combined withshaking table test andnumerical simulation. Firstly, shaking table tests were carried out to find natural vibration period, damping ratios and dynamic amplification factor of test models. Then,thedynamic amplification factor response spectrums were found through finite element models. Finally, spectrums of Numerical simulation, code and fitting were contrasted.The specific content of this paper was as follows:1.The status research of design response spectrum at home and abroad wasintroduced. Summing up the previous research results ofthe design response spectrums at home and abroad, it was found that most of these researchesadopted the theoretical methods. Accordingly, the main point of the research methods, the methods combined withshaking table test andnumerical simulation, wereraised.2.Theshaking table tests were conduct inState Key Laboratory of Subtropical Architecture Science, South China University of Technology. The test models made of organic glass materials in proportion to sizes. To meet the similarity relation, test models externally attached mass. To get four structural damping ratios, different number of dampers set up between the test models and the steel frame fixed on the shaking table. Three seismic waves,Alaska wave, Chichi wave and Kocaeli wave, which were rich of low frequency composition for long-period,were chosen to be input seismic excitation. Acceleration sensors were diagonallyarranged incross even layer.3.Thedatum of long-period shaking table testwas processed. Natural vibration periods of 8layers, 16 layers, 24 layers, 32 layers,40layers,40 layers(full load) model were obtained through auto-power spectrum analysis. Four structural damping ratios were found by half-power bandwidth methods. Dynamic amplification factor of equivalent single degree freedom position and top of test models were obtained by the ratio betweenthe maximum acceleration value of acceleration time histories atthe sameplace of test models and thatvalue at shaking table. Dynamic amplification factor discrete spectrums were found by synthesizing natural vibration period, damping ratios,averagedynamic amplification factor atequivalent single degree freedom position and topof test modelsoftotal reactionand first order mode shape.4.By using the finite element software SAP2000, numerical simulationwerecarried out. 8layers, 16 layers, 24 layers, 32 layers,40layers, 40 layers(full load) numerical model, natural vibration period of which were calculated and compared with natural vibration period ofprototype structure of test model, were established. More numerical modelswith different natural vibration period were built andapplied actual seismic wave to carry on linear time history analysis.The results of simulation were analyzed so that the dynamic amplification factor response spectrumscould be sorted out. Spectrumsof Numerical simulation, fitting andcode were contrasted.This paper got the following conclusion. The methods ofdynamic amplification factor spectrumsresearchcombined withshaking table test andnumerical simulation were feasible. With the change of natural vibration period, structural seismic dynamic responses changed slowly. Structural dynamic amplification factor had a downward tendencywith the change of natural vibration period. The long-period segment in the dynamic amplification factor response spectrum of China code had highervalue.