Seismic Performance of Steel Girder Bridge Superstructures with Conventional Cross Frames

L.P. Carden, A.M. Itani and I.G. Buckle

MCEER-08-0001 | 01/07/2008 | 264 pages

Keywords: Seismic performance.  Steel plate girder bridges.  Superstructures.  Cyclic tests.  Shaking table tests.  Transverse seismic loads.  Flexural-torsional response.  Distribution.  High seismicity.  Deformations.

Abstract: Past earthquakes have shown that the considerable in-plane strength of most bridge superstructures is not always sufficient to prevent damage to components of steel plate girder superstructures during moderate to large earthquake excitation. Cyclic and shake table experiments on a 2/5th scale model of a simply supported steel girder bridge superstructure, with two steel plate I-girders, a reinforced concrete deck slab and single angles cross frames are described in this report. These experiments were conducted to determine the effects of transverse seismic loading on this type of bridge superstructure in high seismic regions. From the experimental results it is shown the superstructure deforms in a flexural-torsional mode with transverse seismic forces distributed along the span and resisted at the supports. At the supports, the loads are transferred from the deck slab into the girders through the shear studs located near the girder supports or through a top chord connecting the deck slab to the end cross frames. The transverse loads are then distributed to the base of the girders through the end cross frames and into the substructure through the bearings and transverse bearing restraints. Each of these critical components should be designed for transverse seismic loading.