SEISMIC RETROFIT MEASURES FOR HIGHWAY BRIDGES-VOLUMES 1 AND 2

Since the San Fernando earthquake in 1971, interest in methods of retrofitting existing highway bridges to provide protection against collapse due to earthquakes has been increasing among highway engineers. In the majority of cases, existing highway bridges in the United States have not been designed to resist the forces generated by seismic activity. As a result, many bridges are subject to some degree of failure under strong seismic loadings. In response to this situation, the FHWA contracted with the Illinois Institue of Technology Research Institute (IITRI) in Chicago, Illinois for the development of a report on seismic retrofitting measures for highway bridges. The primary objectives of the report are to (1) provide current information on the theory and techniques for seismic analysis of highway bridges, including background material on basic structural dynamics, (2) identify the appropriate criteria necessary to decide if a bridge needs retrofitting and the type of retrofit measures to employ, and (3) demonstrate design details and installation specifications for retrofitting existing highway bridges to minimize earthquake damage. This report is in two volumes: Vol 1 Earthquake and Structrural Analysis Vol. 2 Design Manual. Volume two is a design manual and contains illustrations of various retrofit concepts and specific design procedures which can be applied to existing bridges. /FHWA/