ABSTRACT
In order to upgrade design codes for highway bridges, in this paper, a load factor for earthquake load in the LRFD format is investigated, based on limit state probability. An appropriate objective function which measures the difference between computed limit state probabilities and a target one will be minimized to determine load factors. In the past research for steel rigid frame piers an effect of the elastic–plastic response of a structure has been dealt with in approximation by taking into consideration reduction of the response acceleration according to ductility factor µ. This research carries out the elastic–plastic analysis of structures under earthquake load and clarifies the ultimate limit state.
