Experimental Study On Seismic Behavior Of High-rise Building In Liquefied Ground

Earthquake damage indicates the foundation failure due to soil liquefaction often results in collapse of structures. Soil liquefaction is widely concerned. At present, the study of foundation liquefaction is mainly involved in bridge, dam, pipeline, underground structure and so on. The effect of foundation liquefaction on the high-rise building is seldom studied up to now. Therefore, in order to study the dynamic characteristics and dynamic response of high-rise structure in liquefied ground under earthquake, a shaking Tab.le test of high-rise structure in liquefied ground was carried out in State Key Laboratory for Disaster Prevention in Civil Engineering, Tongji University in March 2015. The natural frequency, damping ratio, vibration mode, seismic acceleration response, displacement response, the composition of seismic acceleration response at the top of structure were studied and analyzed. The conclusions drawn from computed results are showed as following:(1)The main damage of high-rise structure is the uneven settlement and lateral tilt after the liquefaction of the soil, while change of the structural damage degree and stiffness is little.(2)According to the analysis of structural acceleration response, in the case of acceleration peak of input seismic wave as the same, the dynamic response of upper structure under the action of El Centro wave is bigger than Kobe wave.(3) According to the analysis of the structural displacement, the displacement increase with the increase of acceleration peak of seismic wave, which indicates that the soil becomes soft constantly and its nonlinear strengthens, the structural stiffness decreases because of crack propagation, and the rocking and swing stiffness of foundation decreases constantly.(4)The seismic acceleration response at the top of high-rise structure is mainly composed of elastic deformation, the second is the rocking and the swing.(5)The process of propagation of input seismic wave from Tab.le bottom to the upper structure, the soil filters the high frequency component of seismic wave, and delivers the low frequency component to the upper structure. The structure absorbs the seismic wave energy by means of the increase of structure damping ratio and elastic deformation, and the decrease of swing stiffness, so as to realize the purpose of shock absorption.The research results of this paper have important significance to improve and develop the theory of seismic design of high-rise buildings, as well as to promote the earthquake prevention and disaster reduction of high-rise buildings.