基于挠度理论的连续梁与悬索组合桥梁结构静力计算

Static calculation of continuous girder-suspension composite bridge based on deflection theory

连续梁与悬索组合桥梁结构是一种新型组合结构体系,其结构受力本质尚不明确,为研究其静力特性,提出了一种基于挠度理论的解析计算方法。首先,假设恒载状态下主缆5段线形,确定恒载作用下主缆的线形公式和主缆内力;其次,将活载作用下结构简化为外伸梁和悬吊钢箱梁部分,考虑之间约束力和弯矩的传递,分别建立其挠度方程,以主缆变形为相容方程,迭代求解结构的内力和变形;最后,以一连续梁与悬索组合桥梁结构的方案设计为例,分别采用所提挠度理论方法、弹性理论方法进行静力计算,并和有限元结果进行对比分析。结果表明:弹性理论计算结果相比有限元结果误差较大,所提挠度理论方法得到的结构主要构件内力和变形值与有限元的计算结果差异很小。所建立的连续梁与悬索组合桥梁结构静力解析计算方法模型简单、计算精度较高,可为此类组合桥梁结构初步计算和设计提供参考。

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.