Cover of Analysis of Seismically Isolated Bridges
Analysis of Seismically Isolated Bridges
  • Publication no: ABC2017-084-17
  • Published: 21 April 2017

The new revision of AS5100.2 is under way and it will include extensive changes to the current earthquake design provisions. These new provisions for earthquake design outlined in the Austroads report AP-T200-12 “Bridge Design Guidelines for Earthquakes” have been recently used on a number of infrastructure projects in Victoria.

The design in accordance with these provisions has resulted in significantly greater earthquake forces compared to the current AS5100 requirements, leading to larger member sizes, and in some cases, to problems with design of foundations governed by the seismic demand. For some of the bridges designed to these new provisions base isolation may prove to be a possible solution. Unfortunately, limited information regarding analysis of seismic isolation systems, including guidelines for non-linear time history analysis, is included in the proposed provisions.

This paper provides an overview of the current practice for design and analysis of base isolated bridges. The paper includes an example of the analysis of the base isolated bridge designed by the author overseas using non-linear time history method.