Fire response of horizontally curved continuous composite bridge girders

This paper presents an approach for investigating fire response of horizontally curved continuous composite bridge girders under localized hydrocarbon fire exposure conditions, considering flexural-torsional-shear coupling effect. A three-dimensional nonlinear finite element model, established using computer program ANSYS and validated through experimental data generated from fire tests, is utilized to analyse the effects, including curvature radius, fire position along bridge span and fire exposed different steel girders, on fire response of a typically horizontally curved three-span continuous composite bridge girder. The predicted results including mid-span deflection, axial displacement and web out-of-plane displacement in different steel girders, are used to quantitatively evaluate fire resistance of horizontally curved continuous composite bridge girders. Findings from analysis results show that curvature radius, fire position along bridge span and fire exposed different steel girders have a significant influence on fire resistance of horizontally curved continuous composite bridge girders. Horizontally curved composite bridge girder with smaller curvature radius presents a lower fire resistance. The outer steel girder governs failure of horizontally continuous composite curved bridge girders subjected to simultaneously hydrocarbon fire and structural loading. Web buckling-based failure criterion is suited to determine failure of horizontally curved continuous composite bridge girders under fire conditions. Therefore, prevention of the outer steel girder from fire can highly improve fire resistance of horizontally curved continuous composite bridge girders.