Seismic retrofitting of highway truss bridges

This paper presents a summary of the recently released document entitled Seismic Retrofitting Guidelines for Complex Steel Truss Highway Bridges (referred to here as the Guidelines). The Federal Highway Administration (FHWA), commissioned MCEER (formally known as the Multidisciplinary Center for Earthquake Engineering) to develop guidelines for seismic retrofitting of steel truss highway bridges as part of a larger research project. The Guidelines list various types and articulations of trusses and define bridge performance levels under the actions of a lower-level (LL) and an upper-level (UL) earthquake. The Guidelines present methods of structural analysis, from simple linear-elastic to dynamic non-linear, time-history, to determine demand on the structure. Methods are presented for determining the capacities of the truss members and there are several examples of retrofit strategies.