Seismic retrofit guidelines for Utah highway bridges.

PDFTech ReportUT-09-062606188RetrofittingEarthquake resistant designEarthquake engineeringHighway bridgesUtahUtah. Dept. of Transportation. Research DivisionWilson, Nash.Ryan, Keri L.Utah State University. Dept. of Civil and Environmental EngineeringUtah. Dept. of Transportation. Research DivisionUS Transportation CollectionMuch of Utah\ue2\u20ac\u2122s population dwells in a seismically active region, and many of the bridges connecting transportation lifelines predate the rigorous seismic design standards that have been developed in the past 10-20 years. Seismic retrofitting methods used in the United States have been investigated for applicability in the state of Utah. The guidelines developed here are based on the Federal Highway Administration\ue2\u20ac\u2122s (FHWA'S) "Seismic Retrofitting Manual for Highway Structures: Part 1 \ue2\u20ac\u201c Bridges," which presents the most current advances in retrofitting and earthquake engineering techniques. As a key difference from FHWA\ue2\u20ac\u2122s guidelines, criteria for selecting earthquake ground motions are based on bridge anticipated service life. Bridges with 30 or more remaining years are analyzed for the 2500 and 500-year return periods, and bridges with less than 30 remaining years are analyzed for the 1000 and 100-year return periods. Flowcharts are provided to assist decision making in retrofit evaluation. The FHWA\ue2\u20ac\u2122s indices method is recommended for screening and prioritizing bridges