Study On Seismic Performance Of Base-Isolated Buildings Under Near-Fault Ground Motions

To study the seismic performance of base-isolated buildings under near-fault ground motions,the pulse identities and response spectrum of near-fault ground motions in major earthquakes of China are investigated,and the cause of severe seismic damage in epicenter of Ludian is explained in the perspective from input earthquake.The retaining wall-isolation layer pounding test is conducted to acquire the pounding model as well as the constitutive model of retaining wall。The pounding model is established based on the Hertz-damp theory and verified by the experiment Through the incremental dynamic analysis of lumped mass model of base-isolated buildings considering the impact of retaining wall,influence of isolation gap size on the collapse performance of base-isolated buildings are detailed analyzed The major conclusions are as follows:1,The LLT record in the Mw6.3 Ludian earthquake in 2014 is a near-fault pulse-like ground motion with a very short pulse period and a high peak velocity The pseudoacceleration spectrum of LLT is much higher than the design spectrum in China in the short period,which explained the severe seismic damage in epicenter of Ludian in the perspective from input earthquake.2,The results of pounding test verify that the pounding from an angle can cause a higher pounding acceleration,thus a higher pounding force.The pounding acceleration has no relationship with the mass of pounding block.3,The retaining wall is simplified to SDOF coupling with an impact element based on the Hertz-damp theory.The results of modelling matches well with the test results.4,The near-fault pulse-like ground motions and their extracted pulses are input the incremental dynamic analysis of base-isolated buildings.There are three types for collapse capacity versus gap size relationship.The proposed model can simulate the influence of pounding velocity on the stiffness of retaining wall.Comparison analysis demonstrate that the single period pulses can not replace the original earthquakes to be the input.