Accurate Stress Analysis on Steel Box Girder of Long Span Suspension Bridges Based on Multi-Scale Submodeling Method

The streamline flat steel box girder is broadly used in long span cable-supported bridges all over the world. As one of the most important part of the bridges, its stress level and distribution under various dynamic loads are especially concerned. However, it is difficult to obtain the accurate stress of the steel box girder by common finite element (FE) calculation. The Runyang Suspension Bridge (RSB) is taken as an example. To increase the accuracy of results, a 3-dimensional FE full model for the RSB is created by ANSYS and a spatial submodel of the steel box girder is particularly built with greater detail. Submodeling method is then employed as a connection technique to link different scale models. After the global analysis and connecting process, the local stress of the steel box girder under various vehicle loads is obtained by submodel analysis. The composite action between the full model and the submodel is analyzed, and the reasonable mesh size for the submodel is specially investigated. The numerical results are proved to be accurate by the field test results. This study demonstrates the reliability and efficiency of the submodeling method; and can provide references for accurately analyzing and designing the steel box girders of other long span bridges.