Seismic Analysis of Precast Segmental Bridge Piers of the Hunter Expressway Viaducts and the Proposed Amendment to Bridge Code AS5100.2

Abstract

The method of deriving the seismic design force in the current Australian bridge design code AS5100.2–2004 is force based and requires the use of a structural response factorRf which is not defined for a structural system consisting of precast segmental concrete piers. There is an initiative to amend the current bridge design code to make it compatible with the changes made in AS1170.4–2007. The initiative also includes displacement based design method as an alternative to the current force based design method. This approach is new in the Australian design offices and there is a need to assess the impact these amendments will create. This paper details the workings of a performance based analysis to derive the seismic horizontal design force for the precast segmental concrete piers which meets the design requirements of the current bridge design code without usingRf. The effect of changes in AS1170.4–2007 and the outcome of implementing displacement based design method in the design of the precast pier have been discussed. The design feature of the Hunter Expressway viaducts which was developed to meet the requirements of AS5100.2–2004 is used to compare the effect of such proposed changes.