Analysis of structural performance of long-span steel trussed arch bridge exposed to fire

Abstract:

To study the effect of vehicle fire on the structural performance of long-span steel trussed arch bridge, a down-supported steel trussed arch bridge with main span of 240 m was taken as the research object for analysis and calculation. First, fire dynamic simulation (FDS) was utilized to simulate the fire temperature field distribution of two typical fire scenarios. Then, the temperature distribution inside the steel member was obtained by finite element instantaneous heat analysis. Finally, the ABAQUS thermal-structural coupling was used to analyze the structural performance variation of the bridge in different fire scenarios. Results show that the highest temperature of the steel arch rib members under the effect of tanker fire was up to 540 ℃. The main load transmitting member yielded at the temperature of 430 ℃, which reached the ultimate limit state, and thermal expansion and internal force redistribution led to the stress increase of the member in the fire area up to 60-180 MPa. The maximum variation of the vertical displacement of the bridge deck was 115 mm, and the maximum lateral height difference of the deck was 108 mm. The oil tanker fire mainly affected the temperature field of the three hanger rods near the fire area. Due to the reduction of the hanger rod force in the fire, the down deflection of the bridge deck was 33 mm and the stress of the main girder increased by 35 MPa.