Study On Seismic Response Analysis Of Isolated Structure Under Near-fault Ground Motion

With the constant research and development of isolation technology and the continuous accumulation of experience in isolation projects,Base-isolated structure has received more and more attention and applications at home and abroad.Scholars at home and abroad have been interested in near-fault ground motions these years since there were some big earthquake in recent years,such as Northridge and Chi-Chi earthquake and so on,and there have been some useful conclusions.The distinct long-duration pulse motion of ground velocity in the near-fault region may cause the adverse influence on the seismic performance of the base isolation building.So in the present paper,it will be discussed that the earthquake response of Frame base-isolated building and Frame-shear Wall base-isolated building under near-fault ground motions.This thesis involves the following work:1.To summarize and analyze the research results and trends of isolation technology at home and abroad.In recent years,studies on seismic responses of structures under near-fault ground motion have drawn attention to the seismic performance of isolated structures.A recent study on near-fault ground motions was introduced,focusing on the special motion characteristics of near-fault ground motions.2.Different characteristics of near-fault ground motions from Taiwan Chi-Chi earthquake is chosen,which spectrum analysis is carried out on.It is found that rich low frequency component is included in near-fault with two horizontal components of ground motions,which will cause adverse influence on long-period structure.The velocity pulse is an important factor that affects the long-period structure in near-fault ground motions.The peak value of the hanging-wall ground motion is greater than the peak value of the foot-wall ground motions.The distribution area of strong earthquakes is larger than that of the foot-wall and the distribution of response spectrum is inhomogeneous.3.Rubber isolation bearings have been widely used in the construction of high-intensity buildings and the isolation of bridges.The classification of the isolation bearings,the mechanical properties and the dynamic analysis model of the isolation structure are introduced,and the composition of the isolation device and the role played by the earthquake are briefly summarized.4.A five-story frame structure as an example,Application of Etabs software to dynamic response analysis of non-isolated and isolated structures in near-fault areas.The seismic displacement of isolated structures under near-fault ground motion has a significant decrease compared with that of traditional seismic structures.This is because seismic energy consumption is mainly concentrated on the bearings.The deformation of the isolation structure is concentrated in the isolation bearing.5.It includes the influence on seism response of Frame-shear Wall base-isolated building of hanging-wall and speed pulse and rupture directivity,and vertical accelerational effect.It is found that under the ground motions with rupture forward directivity the seism responses is the grater followed by ground motion with fling-step,and the ground motions without pulses is the smallest.The seismic response of the Frame-shear Wall base-isolated building under the action of the hanging-wall ground motions is larger than that of the foot-wall in most aspects.the normal component of fault is greater than the parallel under which the seism response of SSI multilayer ground base isolation building.