Shaohong Cheng

Impact of Key System Parameters on the In-Plane Dynamic Response of a Cable Network

AbstractUsing crossties to connect a cable which has experienced or is prone to violent motions with its neighbors and form a cable network has been successfully applied to a number of cable-stayed bridges to control stay cable vibrations. However, matured guidelines for designing crossties are still lacking. The present study aims at identifying key system parameters which dictate the in-plane dynamic behavior of a cable network and evaluate their respective roles. An analytical model of a general cable network consisting of n horizontally laid cables interconnected by a single line of transverse rigid crossties will be developed, based on which the key system parameters will be identified from the system characteristic equation. An extensive parametric study will be conducted to assess the impact of these parameters on the dynamic response of cable networks. The outcome from the study is expected to not only comprehend our understanding in the mechanics associated with cable networks, but also shed ligh...

Effect of the Number of Cross-Tie Lines on the In-Plane Stiffness and Modal Behavior Classification of Orthogonal Cable Networks with Multiple Lines of Transverse Flexible Cross-Ties

AbstractUsing cross-ties to connect a vulnerable cable with its neighbor(s) and forming a cable network is a common countermeasure to suppress bridge stay cable vibrations. An effective design of cross-tie solution should provide an optimum combination of cross-tie installation location, stiffness, and number of cross-tie lines to maximize the network in-plane frequency and structural damping while minimizing the number of excited local modes. However, the mechanics associated with cable networks is not as simple as their geometrical appearance. In particular, the addition of an extra line of cross-ties to an existing cable network would considerably increase the complexity of its structural behavior. While the effects of cross-tie position and stiffness on network response have been investigated in some existing studies, that associated with the number of cross-tie lines is scarce. For better understanding of how the dynamic behavior of a group of cables would be influenced when interconnected by differe...

Assessment of damper performance in controlling cable vibrations using a reliability-based framework

Owing to their long flexible nature and low intrinsic damping, bridge stay cables are prone to various types of wind-induced vibrations, among which the rain-wind-induced vibration is most frequently observed on site. External dampers are widely used to control such unfavourable cable oscillations and their effectiveness in suppressing large-amplitude cable vibrations was addressed in many studies using deterministic approaches. However, the mechanical and/or physical properties of cables and the attached dampers could not only deviate from their respective nominal design values at a given design point, but also vary considerably during the lifetime of a cable-stayed bridge and thus affect damper efficiency. Hence, for a realistic damper performance assessment, these uncertainties should be taken into account. The objective of this paper is to present a time-variant reliability-based framework model to assess how uncertainties in the structural parameters of a cable-damper system would influence the time specific reliability performance of an external damper yielded from the current design practice.

Impact of Cross-Tie Properties on the Modal Behavior of Cable Networks on Cable-Stayed Bridges

Dynamic behaviour of cable networks is highly dependent on the installation location, stiffness, and damping of cross-ties. Thus, these are the important design parameters for a cable network. While the effects of the former two on the network response have been investigated to some extent in the past, the impact of cross-tie damping has rarely been addressed. To comprehend our knowledge of mechanics associated with cable networks, in the current study, an analytical model of a cable network will be proposed by taking into account both cross-tie stiffness and damping. In addition, the damping property of main cables in the network will also be considered in the formulation. This would allow exploring not only the effectiveness of a cross-tie design on enhancing the in-plane stiffness of a constituted cable network, but also its energy dissipation capacity. The proposed analytical model will be applied to networks with different configurations. The influence of cross-tie stiffness and damping on the modal response of various types of networks will be investigated by using the corresponding undamped rigid cross-tie network as a reference base. Results will provide valuable information on the selection of cross-tie properties to achieve more effective cable vibration control.