Seismic retrofit of slab-on-girder steel bridges

Thin steel infill plate has been proposed in the past as a ductile end diaphragm to reduce the transverse seismic demand in slab-on-girder steel bridges. However, a simplified method is required to promote the use of steel infill plate end diaphragms as a retrofit strategy. In this paper, the retrofitting strategy is based on the ductility reduction factor (R-mu) provided by the addition of steel infill plate. A step-by-step procedure is developed to calculate the ductility reduction factor which reduces the force demand on vulnerable substructure elements. In addition, this procedure is shown to give results that compare well with numerical data from finite-element analysis.