Seismic fragility curve assessment of multi-frame steel box-girder bridges in Iran

Numerous of the most recent steel box-girder bridges in Iran are horizontally and vertically curved. Thecurvature both in vertical and horizontal direction in multiframe bridges lead to significant differences in bridgedynamic response during seismic excitations. In this article, a set of analytical fragility curves for horizontally andvertically curved highway bridges are developed based on nonlinear time history analyses in OpenSEES, focusingon subclasses of seismically designed multiframe box-girder bridges with single column bents and seat typeabutments. Component damage levels are explored for joint seals, columns, bearings, abutments, unseating ofdecks, foundations, and shear keys, and system level damage states consistent with HAZUS-MH definitions.Curvature was identified to be an important factor that adversely affects the fragility of multiframe bridges in bothdirections. Median value modification factors are proposed to scale fragility curves to account for the deck radiuseffects.

Keywords:

Fragility Curves , Seismic Assessment , IDA , Multiframe Bridges , Curved bridges