Comparisons of international seismic code provisions for bridges

This thesis presents a comparison between the AASHTO-2004, BSI-EN1998-2:2005, NBCC-2005 and the 2007 proposed AASHTO LRFD seismic design provisions with that of the 2006 CSA S6 Canadian Highway Bridge Design Code (CHBDC). A regular 2 span-90m long bridge was used to apply the seismic design loads determined from the codes investigated. The superstructure consists of a 2-lane prestressed concrete box girder, supported by a single column and two abutments. The single column is a 2400 mm circular pier with two different amounts of longitudinal reinforcements. One column had 36-45M longitudinal bars, transversely tied with 15M bars spaced at 50 mm. The second column contained 36-55M bars. The design of the bridge was carried out for three different seismic regions, Montreal, Toronto and Vancouver. In addition, the soil conditions were assumed to match those of NEHRP Soil Profile Types B and E. The research compared the effects of the seismic design spectra and overstrength factors in developing the design moments, shears and displacement ductility demands of the bridge.This research provides recommendations for updating the current CHBDC seismic design provisions.