Equivalent Lateral Force Design Method for Irregular Straight Multi-Span Bridges with Bidirectional Ductile End Diaphragm

The equivalent lateral force method developed to seismically design longitudinal buckling restrained braces (BRBs) in bidirectional ductile end diaphragms in simply supported straight multi-span regular bridges, is evaluated here for its applicability to design irregular bridges. A wide spectrum of irregular multi-span bridges was considered, per the irregularity bridge definition of AASHTO. The seismic behavior of the designs obtained was then evaluated using non-linear response history analysis. Results obtained showed that this simple design method 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 for the BRBs.