A component mode synthesis method for reduced-order modeling of cable networks in cable-stayed bridges

Abstract

Cables in cable-stayed bridges become increasingly long and interconnecting them using cross-ties to form a cable network is a promising method for suppressing their vibrations. Dynamics of such cable networks is complicated and not well-understood particularly for real networks consisting of many cables and cross-ties. This study proposes a general numerical model for free and forced vibration analyses of cable networks based on the component mode synthesis method. The model is developed by regarding each cable as a substructure and the dampers/cross-ties as massless interface elements. A coupling scheme is then presented to formulate the system model from the cable model and mechanical properties of the dampers/cross-ties. Model order reduction is realized for each cable using the modal truncation method in combination with generalized quasi-static correction modes to account for the damper/cross-tie induced discontinuity of cable responses at the connection points. Subsequently, free vibration analysis of typical cable networks has been conducted using the model, and the computed frequencies and mode shapes are found in excellent agreement with the close-form solutions, suggesting the effectiveness and accuracy of the method. Furthermore, the model is shown to be more efficient as compared to a finite difference model in forced vibration analysis of a three-cable network with an elastic cross-tie and near-anchorage dampers.