OVERVIEW OF THE 2007 LRFD GUIDE SPECIFICATIONS FOR SEISMIC DESIGN OF BRIDGES

A new, long awaited, AASHTO LRFD Guide Specification for Seismic Design of Highway Bridges has been developed under the guidance and support of the AASHTO T-3 Committee on Seismic Design. This paper will give a brief history and background on the development of the Guide Specifications to meet the expectations of the T-3 Committee. The Guide Specifications were developed specifically for ordinary, girder and slab type bridges, using a Displacement Based Approach with design factors calibrated to prevent collapse and reflect both the inherent reserve capacity to deform under imposed seismic loads and to accommodate relative displacements at the supports and articulated connections. This presentation will focus on the selection of the seismic hazard and give a brief overview of the new specification. Introduction and Background The work that led to the recent adoption of the AASHTO LRFD Guide Specification for Seismic Design of Highway Bridges began with the development of