Thermo-Structural Response of Highway Bridge Structures with Tub Girders and Plate Girders

Abstract

Fires from vehicular accidents involving heavy-goods vehicles (HGVs) pose a significant threat to steel plate girder highway bridges. The complete immersion of plate girders in flames resulting in excessive girder element temperature is hypothesized to be a gauge of the fire performance of highway bridges. This research investigated the effect of girder geometry on the flame dynamics and fire performance of typical steel girder–concrete deck highway bridges. As part of the study, the thermo-structural response of a standard single-lane steel girder–concrete deck composite assembly made of three plate girders and a single tub girder exposed to a HGV fire was evaluated. It was predicted that the single-lane highway bridge made with plate girders would fail with exposure to a HGV fire, whereas the bridge with a tub girder was predicted to maintain structural integrity for the total fire duration. The tub girder design was determined to provide superior resistance to collapse compared with multiple-plate girders because of its lower temperature rise and higher moment resistance. The study also investigated the effect of inclusion of a flame shield between the plate girders and multiple tub girders on the fire performance of highway bridges.