Purpose This paper aims to investigate the behavioral response of medium-span composite steel-concrete bridge girder subject to various short duration, localized fires. It employs the usage of coupled computational fluid dynamics (CFD) model and the finite element analysis (FEA) modeling to accurately examine the structural response during and after fire exposer. The study aims to expand the current understanding of localized fires by varying the fire’s location and intensity, while simultaneously assuming a short burning time. Design/methodology/approach The study adopts a numerical approach to investigate the thermos-mechanical response of a structure exposed to elevated temperatures. A coupled CFD-FEA framework was used to analyses the structures’ behavior during and after fire. The models’ parameters were complimented by already performed experimental results. The numerical results were validated by using simple theoretical calculations and already established numerical models. Findings The findings provide insight into the structural response of composite steel-concrete bridge girder during and after fire exposure. The results indicate that the load-bearing capacity is significantly influenced by the fire’s location and intensity. In the case of mild fires, structural deflection remains limited, suggesting the feasibility of post-fire repair. Furthermore, the analysis demonstrated that creep strain can be neglected in case of short duration fires. Additionally, the study quantifies the cross-sections deformation in relation to time allowing for a deeper understanding of heating and cooling effects on the structure. Research limitations/implications A limitation of the study is the study lacks experimental validation for the FEA models. Therefore, researchers are encouraged to perform further tests on the proposed propositions and expand the database of structural responses to short fires. Practical implications The paper provides a comprehensive example of advanced fire analysis of a bridge structure, offering a solid framework that can be replicated. By documenting the full modeling process and results, the paper contributes to the widening of the database of structural responses under elevated temperatures and supporting future research and improvement of design guidelines. Originality/value This paper provides new insights into the effects of short duration, localized fires on composite steel-concrete bridge structure. It additionally examines the influence of creep strain effects and air-cooling rate of steel.
Maglica et al. (Mon,) studied this question.