Longitudinal Stiffness of Multispan Suspension Bridges

The longitudinal stiffness of multispan suspension bridges plays an important role in load-resisting systems. In this paper, a model defined as the kinematic multispring (KMS) model is proposed for simulating the longitudinal deformation behavior of multispan suspension bridges. Tower springs and cable springs constitute a series-parallel system in the KMS model. The stiffness formulas for cable springs were derived on the basis of the energy principle. The elastic elongation of the cable was considered and proved to be nonnegligible, especially for long-span bridges. The effect of the inclined angle of the cables was first considered in the formulas for the cable elastic stiffness. The elastic stiffness and the geometric stiffness of the cables were found to be relevant. Compared with numerical models, the KMS model proposed in this paper was proven to be accurate and applicable.