Seismic Design Criteria for Bridges and Other Highway Structures

Keywords: Research needs. Design criteria. Highway bridges. Design strategy. Transportation lifelines. Code requirements. Code development. Abutments. Retaining walls. Tunnels. Two level design methods. Europe. Japan. United States. New Zealand.
Abstract: This report presents the results of one component of the ATC-18, namely, review of seismic design criteria for highway bridges and other highway structures. It covers current design practice and criteria, ongoing research and development in design criteria, philosophies behind design approaches for highway bridges, tunnels, and retaining structures. Particular attention was given to foundation design. The study involved a review of existing US standards along with the latest codes of Japan, New Zealand, and Europe. Guidelines developed for the Transportation Corridor Agencies for Orange County, California, and the new AASHTO Load and Resistance Factor Design (LRFD) Bridge Specifications were also reviewed. Issues addressed included performance criteria, importance classification, definitions of seismic hazard for areas where damaging earthquakes have longer return periods, design ground motion, duration effects, site effects, R factors, ductility demand, design procedures, foundation and abutment modeling, soil-structure interaction, seat widths, joint details, and detailing for limited ductility. The final phase of this ATC-18 project was to develop recommendations for the future direction of seismic code requirements. This was achieved by outlining a future standard which, among other things, incorporates a two-level design approach. Also reviewed in this report is information from the ongoing ATC-32 project, a revision of Caltrans Bridge Design Specifications (Caltrans, 1993). (Abstract adapted from text).