A Comparative Study on Seismic Response of Isolated Continuous Girder Bridges with SRB and LRB

To investigate the difference on isolated continuous girder bridges with SRB (SMA rubber bearings) and LRB (lead rubber bearings),the G-C model was adopted to simulate the thermodynamic equation constitutive relation of SMA (shape memory alloy) fiber, and Bouc-Wen restoring force model was used to simulate the LRB nonlinear hysteretic characteristics. FEM computation model of the entire bridge was established by the way of making the structure discrete. Further, the time history analysis program was prepared to solve the nonlinear motion equation of the isolated structure with SRB and LRB. The comparative analysis of time history was implemented for no-isolated, SRB and LRB isolated bridges under different kinds of seismic excitations by using the prepared program. The results indicate that, under non-low frequency pulse seismic excitations, the beam displacement is amplified by SRB and LRB isolation,but the maximum beam displacement is still within the range of standard and the seismic response of other key positions is decreased obviously. For the low frequency pulse seismic excitations, the isolating rate of SRB is still good, while the response of isolated bridges with LRB is much bigger than that of the non-isolated bridges, and its beam displacement might exceed the range of standard.