Study of seismically isolated bridges with LRB

Through nonlinear time history analysis of seismically isolated bridges with the use of large numbers of seismic waves,which have the same response spectrum,it is found that the maximum response is differs widely.The maximum response of nonlinear structures is sensitive to the total process of seismic ground motion.Five equivalent linear methods for the seismic analysis of seismically isolated bridges have been compared.The study proves that the degree of reliability of results,which are calculated by response spectrum using equivalent linear models,does not remain the same as the bearing ductility ratio varies.In usually ranges of bearing ductility ratio,the results calculated by those equivalent linear methods are not safe.