The Ingenieur Vol 59 July-Sept 2014 The Ingenieur Vo. 59, July-Sept 2014 | Page 37

Conclusion
The specification for manufacture and installation
of bridge bearings need to be revised based on
seismic isolation specifications. Seismic Isolators
should be firmly fixed to the substructure and
super structure with holding-down and holdingup bolts other those laid directly on concrete or
other bedding materials to prevent problems due
to walking bearings
The free vibration analysis shows that with
more flexible bearings in shear direction, bigger
periods are expected for bridges in the horizontal
direction. Longer periods provide less response
and produces better overall bridge performance.
The response of the bridge is amplified from
the ground to the top of the pier fitted with fixbased bearings and rubber bearing pads. However,
the performance of the bridge was enhanced by
using seismic isolator bearings by decreasing the
amplification. The bridge with seismic isolator
models also shows the reduction in moment up
to 60% compared to the bridge with normal rubber
bearing pads.
Finally, the time history results show that
serious damage will not occur on the Second )A