Obtaining seismic fragility curve of curved steel box-girder bridges

The current study presents the effect of geometric parameters such as horizontal curvature, and columnheight on the seismic response and fragility of curved multi-frame concrete box girder bridges. The model is usedto perform a set of nonlinear time history analyses for a ground motion suite to compute the fragility function ofcomponents and system. Moreover, multiple levels of each geometric parameter are determined to identified theeffect of geometry. As-built bridge models are modified by varying one of each parameter and the modified modelsare repeatedly simulated for the seismic fragility assessment. Component damage levels are explored for joint seals,columns, bearings, abutments, unseating of decks, foundations, and shear keys, and system level damage statesconsistent with HAZUS-MH definitions. Median value modification factors are proposed to scale fragility curves toaccount for the deck radius effects. the column height is the most influence parameter affecting the system fragilitywhile the horizontal curvature and abutment skew have a relatively minimal influence on the system fragility of thisclass of bridges.

Keywords:

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