Abstract:To research the mechanical performance of steel composite continuous girder when exposed to oil tanker fire,ANSYS finite element model of a three-span steel composite continuous girder was built by the Thermo-Mechanical coupling analysis method.By analysising the temperature field distribution of steel composite continuous girder under oil tanker fire,the model simulated vertical temperature gradient of the girder and load-displacement curve of key section. Moreover,attenuation rule of steel composite continuous girder ultimate bearing capacity under different bridge fire scene get closer to public.The research conclusion shows that,the proposed method could predict temperature response of steel composite continuous girder.When a fire broke out under the bridge,the temperature of steel girder get great rise.According to the distance to the combustion source,base-steel get the higher temperature,web-steel get the medium temperature,top-steel get the lower one without doubt.But concrete get a slow temperature rise.When a fire occur on the bridge,concrete get a higher temperature than opposed to under-girder fire.While steel girder get a opposite conclusion.When it comes to the loss of ultimate bearing capacity of bridge,under-bridge fire scene is severer than on-bridge fire scene. Key words:steel composite continiuous girder;temperature field;ultimate load;failure mechanism;finite element model

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