Study On Identifying Velocity-pulse Ground Motion And Infulence On Isolated Structure

Isolated structures have good resistance to earthquake in general far-field earthquake,but near fault ground motion has characteristics different from common ground motion,which leads to greater damage,especially for long period or isolation structures.The main reason is the influence of velocity pulse.The design of isolation structure is usually based on ordinary far-field ground motions.With the large-scale development of seismic isolation structure,it is necessary to study the influence of velocity impulse ground motion on the base isolated structure and perfect the design theory of near fault isolation structure.In this paper,two problems are investigated,one is how to quantify the ground motion with velocity pulse,and the other is to study the effects of these two ground motions on the response of base isolated structures.The main contents and conclusions are as follows:1.Three kinds of pulse-like ground motion identification methods are introduced briefly.Including Baker(2007)based on wavelet analysis,Zhai(2013)based on energy.Because the two methods do not take full account of the diversity of pulse shape,and the subjective preset parameters are too many.Therefore,the method using IMF reconstruction is more applicable in earthquake engineering due to its advantages in configurational asymmetrical pulse determination.2.Using Sap2000 analyzes the response of the isolated structure with 5,10 and 15 layers respectively,which is controlled by three parameters(the same energy,PGA and PGV).The results show that the displaces and base shear have a strong response under three conditions,others parameters(velocity,acceleration and displacement Angle between layers)have no obvious specific feature.The results of this paper reveal the adverse effects of near-fault pulse-like on the base isolated structures,and provide some valuable suggestions for seismic design of base isolated structures in near fault regions.