Experimental Study of Vibration Characteristics of FRP Cables for Long-Span Cable-Stayed Bridges

Abstract

This study describes an investigation of vibration characteristics of carbon fiber-reinforced polymer (CFRP) and basalt FRP (BFRP) cables that can potentially be used in long-span cable-stayed bridges, compared with the traditional steel cable. Reduced-scale cable models were designed using similarity criteria and verified by examination of their dynamic characteristics. In-plane and out-of-plane vibration experiments on model cables were conducted using the step excitation method. The natural frequencies and modal damping of the cables were analyzed further, and the modeling of the damping ratios was studied using Rayleigh’s method. The results indicate that (1) the model cables well represent the dynamic properties, i.e., the equivalent natural frequencies of real long-span cables; (2) the probability of cable-deck resonance of bridges with FRP cables is lower than that of bridges with steel cables; (3) the damping properties of FRP are complex because of their inherent nonlinear material characteristics, but the equivalent damping of in-plane vibration of FRP cables is generally much larger than that of steel cables, whereas the equivalent damping of out-of-plane vibration of FRP cables is smaller than that of steel cables; and (4) the modal damping ratio of out-of-plane vibration can be accurately simulated by Rayleigh damping.