Analysis and simplified calculation method of the steel-concrete composite girder bridge

Compared to the simply supported concrete bridge with concrete continuous layer (Structure 2) and steel-concrete composite girder with concrete continuous deck (Structure 3), the steel-concrete composite girder with concrete continuous layer (Structure 1) are more likely to be damaged. In order to study the simplified calculation method of the Structure 1, the field test of a Structure 1 was carried out, and the simplified method was deduced. The shell-solid and multi-scale finite element models of the Structure 1 were established, and the model results were compared with the tested results. Finally, parameter analysis by models and the simplified method were compared. The results showed that the calculated strains of the concrete continuous layer were close by multi-scale models and shell-solid models, and in good agreement with the experimental values, but the calculation efficiency by multi-scale model is significantly improved about 3.4 times than shell-solid model. Two dimensionless parameters, t_d/h_c (ratio of the thickness of the concrete continuous layer to the depth of the composite girder) and h_c/l (ratio of the depth to the bridge span), have the greatest influence on the strain of the concrete continuous layer, and the strain difference is both more than 20 % with the variation of t_d/h_c and h_c/l, which cannot be ignored. The φ_x (longitudinal reinforcement ratio) and l_d/l (ratio of the length of the joint to the bridge span) have the second influence on the strain of the concrete continuous layer, and the strain difference is about 10–20 % with the variation of φ_x and l_d/l, which also cannot be ignored, while the E_d (elastic modulus) and φ_y (transverse reinforcement ratio) have a little influence on the strain of the concrete continuous layer, and the strain difference is almost less than 1 %, which can be ignored basically. After linear fitting between the results by multi-scale models and the simplified method, the calculation deviation between them is not more than 10 %. Therefore, it can be considered that the multi-scale model and the simplified method can efficiently and accurately calculate the stress of the concrete continuous layer of the steel-concrete composite girder bridge.