ABSTRACT
Seismic design of bridges as we know it today in the United States began at California Department of Transportation (Caltrans) immediately aer the San Fernando earthquake on February 11, 1971. e rst seismic design criteria (SDC) that followed was implemented into Caltrans design practice in 1973 (Imbsen and Gates, 1973). is was a prescriptive design criteria based on a ductile design approach with prescribed ductility factors to allow damage and to avoid collapse. Allowing damage to occur with the formation of plastic hinges in the columns provides a performance level of “life safety.” is ductile design approach was selected instead of a more costly and dicult to achieve elastic design. is approach was
7.1 Background ........................................................................................237 7.2 Introduction ......................................................................................239
