Laboratory-Scale Experimental Setup for Studying Cable Dampers

This study proposes a laboratory-scale experimental setup that simulates the dynamics of a full-scale stay cable with a transverse damper, allowing the full-scale performance of different types of dampers to be evaluated and compared in a laboratory setting. This test scheme resembles hybrid testing in that it retains the physical structural component for experiments, whereas it uses an equivalent model to represent the large-scale main structure instead of the numerical simulation used in a hybrid test. For the cable, a feasible model is presented that is composed of two flexible beams that are suspended vertically, fixed at their upper ends, and connected at their lower ends by a rigid mass; the damper is attached transversely to one of the beams. The setup is modeled as tensioned beams for clamped-guided supports with a terminal mass and an intermediate damper for dynamic analysis, and the characteristic equation is formulated from dynamic-stiffness matrices of beam segments. Modal properties of the setup are found to be similar to those of a cable-damper system, based on which the equivalence conditions are presented. The established equivalence between a cable and a model is further found to be roughly independent of damper properties for practical applications, therefore ascertaining the potential of this setup for a cable-damper study. Experiments have also been conducted in which the damper performance is evaluated on a full-scale cable and on a beam-mass assembly designed to represent the first vibration mode of the stay cable. The amplitude-dependent damping ratios achieved in the laboratory setting are found to be comparable to those achieved for the full-scale cable, suggesting the applicability and effectiveness of this experimental setup. (C) 2014 American Society of Civil Engineers.