Seismic Design of Bidirectional Ductile End Diaphragms in Irregular Straight Multispan Bridges

Methods previously developed to seismically design longitudinal buckling restrained braces (BRBs) in bidirectional ductile end diaphragms in simply supported straight multispan regular bridges, are evaluated here for their applicability to design irregular bridges. A wide spectrum of irregular multispan bridges was considered, per the irregularity bridge definition of AASHTO. The seismic behavior of the designs obtained was then evaluated using nonlinear response history analysis. Results obtained showed that these simple design methods developed for regular bridges can also be applicable to irregular bridges of up to seven simply supported spans, with response remaining within the prescribed performance limits, as long the equivalent lateral force method also prescribes a minimum cross-section area.