Analytical Study on the In-Plane Dynamic Behavior of Cable Networks Consisting Flexible Low-Sag Cables

Date of Award

5-31-2023

Publication Type

Thesis

Department

Civil and Environmental Engineering

Keywords

Cable network, Cable vibration, Control vibration, Cross-ties, Dynamics, Nonlinearity

Supervisor

S. Cheng

Supervisor

L. Sun

Rights

info:eu-repo/semantics/embargoedAccess

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

Abstract

Stay cables are important load carrying members in cable-stayed bridges. Due to their high lateral flexibility and low inherent damping, stay cables are susceptible to dynamic excitations and prone to large amplitude oscillations that could negatively affect bridge functionality and safety. Connecting a vulnerable cable with the neighboring ones through transverse cross-ties to form a cable network is a cable vibration control strategy commonly used in practice. This dissertation aims to investigate the in-plane dynamic behavior of cable networks by taking into account several practical properties of main cables and cross-tie(s).

A number of analytical models have been developed to take into account respectively the effect of cable bending stiffness, cable sag, the combined effect of these two, and the impact of cross-tie material nonlinearity on the in-plane modal response of cable networks. Independent numerical simulations were performed to validate all the proposed analytical models using the commercial finite element software ABAQUS 12. Results indicated that while cable bending stiffness would influence all cable network modes, sag would only impact the symmetric modes. Both of these two cable properties have a stiffening effect on the affected modes with that of the sag being more sizable. In addition, it was revealed that cable bending stiffness would have more considerable stiffening effect on high order global and local modes. The modal cross-over phenomenon, which is originally observed in a single sag cable, was also observed in shallow cable networks. The modal cross-over was found to occur between two global modes, as well as between a global mode and a local mode, if they are the same order symmetric and antisymmetric modes. Further, it was learned that the presence of material nonlinearity in a cross-tie would not only lead to a reduction in the frequencies of all the modes, but the formation of local modes would also be delayed to high order.

In addition, an analytical model for the in-plane dynamics of a single flexible low-sag cable with an intermediate transverse elastic support was proposed. The impact of the intermediate support stiffness, location, cable bending stiffness, and sag on the in-plane modal response and the modal cross-over of a single shallow flexible cable was examined using the proposed analytical model. Results showed that the installation of an intermediate transverse elastic support breaks the symmetry and anti-symmetry of the original single cable mode shapes, which makes all cable modes susceptible to the sag effect. The level of this distortion in cable mode shapes would also govern the occurrence of modal cross-over.

This dissertation contributes to the knowledge associated with the dynamic behavior of cable networks in cable-stayed bridges. The developed analytical tools and closed-form solutions would be of great assistance to the bridge industry by allowing more accurate, realistic, and reliable predictions of cable network system response at both the preliminary design stage and in the rehabilitation process of cable-stayed bridges. The findings from the current study will help to have a better understanding of structural health monitoring, assessment and management of bridges, which contribute to develop more sustainable civil infrastructure and thereby benefit global economy.

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