Ambient vibration and seismic evaluation of a cantilever truss bridge

An experimental ambient vibration field investigation with a companion comp utational modeling study of a cantilever truss bridge is presented. The amb ient vibration experiments were conducted on the central suspended span and two adjacent anchor spans of the North Grand Island (NGI) Bridge. Three-di mensional finite element model of the bridge is validated against the exper imental results. Results from time history analyses using selected ground m otions are used to assess the damage threshold of the bridge. A nonlinear s tatic procedure using the capacity-demand spectrum approach is then employe d to evaluate the expected seismic performance of the structure. Results sh ow that sway frame members are especially prone to damage under earthquake- induced deformations. However, overall response of the structure may be con sidered satisfactory from a life safety standpoint. (C) 2001 Elsevier Scien ce Ltd. All rights reserved.