Find seismic design and retrofit information for new and existing structures.
Related manual chapters
Chapter 4 - Seismic Design and Retrofit (PDF 4.7MB) provides guidance for expected bridge performance and post-earthquake service levels. This chapter details WSDOT additions and modifications to the AASHTO Guide Specifications for LRFD Seismic Bridge Design. It also includes design requirements for widening projects, retrofit projects and walls and buried structures.
Bridge Design Manual
Complete Bridge design guidance is found in the Bridge Design Manual (M 23-50).