The present study proposes a practical yet reliable model for stay cables in cable-stayed bridges considering large force variation under seismic actions. The proposed model is capable of approximating the nonlinear equivalent stress-strain relationship of cables, taking into account the variation of equivalent modulus of cables during the earthquake as well as possible cable loosening. The cable performance based on the proposed method shows an overall good agreement with the actual response of cables. Then, the model is applied to a case cable-stayed bridge under seismic actions and the structural response is compared with the conventional method which models the cables with a constant equivalent modulus derived at dead load state. Comparing to the proposed model, the conventional method fails to accurately describe the cable force at the low stress level and shows discrepancies in time histories of the structural response in terms of amplitude and phase angle. Moreover, conventional method might lead to underestimation of the bending moment at the tower bottom and longitudinal displacement at deck end for most cases, resulting in unconservative seismic design. Such result highlights the importance of applying the proposed model in seismic design of cable-stayed bridges.

本研究提出了一种实用而可靠的斜拉桥斜拉桥模型，考虑了地震作用下的大力变化。考虑到地震过程中电缆等效模量的变化以及可能的电缆松动，所提出的模型能够近似估算电缆的非线性等效应力-应变关系。基于所提出的方法的电缆性能与电缆的实际响应显示出总体良好的一致性。然后，将模型应用于地震作用下的斜拉桥，并将其结构响应与常规方法进行比较，该方法以恒载等效状态下的恒定等效模量对缆索进行建模。与建议的模型相比，传统方法无法准确地描述低应力水平下的电缆力，并且在振幅和相位角方面显示出结构响应时间历史上的差异。而且，在大多数情况下，常规方法可能导致低估塔底弯矩和甲板端纵向位移，从而导致设计不保守。这样的结果突出了在斜拉桥的抗震设计中应用所提出的模型的重要性。