Refined analysis of steel girder bridges for computation of live load distribution factors considering effects of freight and emergency vehicles

•Refined analysis method is used to compute load distribution factors for 21 in-service steel girder bridges.•The impacts of special hauling vehicles and emergency vehicles on the load distribution behavior are investigated.•Regression models are developed to predict distribution factor of bridges with different geometrical characteristics.•The models can serve as screening tools to provide guidance on the use of refined methods of analysis for bridge load rating.