Abstract：The continuous girder-suspension bridge is a new-type composite bridge, but its mechanical behavior hasn’t been understood very well. To study its static behavior under loading, an analytical calculation method based on the deflection theory was proposed. Firstly, the main cable was supposed to be the shape of 5 segments under the dead loads, and then the shape formula and tension of the main cable were analytically determined. Secondly, the structure under live loads was simplified into two parts, namely the overhanging girder and the suspended steel-box girder. By considering the transfers of constraining forces and moments between the two parts, the deflection equations of the two parts were derived, respectively. Based on the compatibility equation for the deformation of the main cable, the internal forces and deformations of the continuous girder-suspension composite bridge can be solved iteratively. Finally, with the design of a continuous girder-suspension composite bridge as an example, the static calculation were carried out based on the proposed deflection theory and the elastic theory, respectively. The results from two theoretical methods were compared with those from finite element method. It is concluded that the elastic theory may lead to relatively larger errors compared to the finite element calculation. Very small differences in the internal forces and displacements of the main members calculated by the proposed method and the finite element method can be observed. Hence, it can be concluded that the proposed analytical calculation method is simple and accurate, and can be referred to by the preliminary calculation and design of such a kind of continuous girder-suspension composite bridge.
