Modal characteristics of tower-cable system in construction state of suspension bridge

Abstract

This paper presents theoretical studies on modal properties of the tower-cable system at the construction state of suspension bridge. The finite element modelling for the system is established, in which the tower legs and cross-beams are modelled as three-dimensional Timoshenko beam elements and the cables are modelled by means of a series of two-node cable elements accounting for the geometric and large deflection stiffness. Based on the proposed finite element modelling, a three-dimensional finite element program has been developed and the modal analysis of the tower-cable system is performed. A comparison is made between the modal properties of cable-connected tower and those of free-standing tower. Some important modal characteristics of the tower-cable system are found. The comparison with the field measurements indicated a good agreement between theoretical and experimental results. The conclusions obtained give a good understanding to the dynamic behaviors of the tower-cable system, and they will be useful in structural damage monitoring and the employment of vibration control measures during the construction stage of the suspension bridge.