Experimental study on the pendulum-type tuned mass damper utilizing wire rope springs

Abstract

Installation of a pendulum-type tuned mass damper (TMD) is one of the most effective solutions to mitigate wind-induced vibrations of tower-like structures such as steel chimneys. Unlike the conventional TMD, which employs viscous dampers as the main damping component, the introduced system utilizes wire rope springs, through which both stiffness and damping can be adjusted. However, due to nonlinear characteristics of the wire rope springs, there is currently no simple general parameter method for an optimal design of the damping system. This study will present data that will be used for design development. Dynamic properties of the wire rope springs were investigated and observed. The dynamic properties of wire rope springs, damping ratio and stiffness, were obtained through free vibration tests of a full-scale pendulum ring TMD model with up to four wire rope springs attached. In comparison with prior studies, roll and tension-compression modes of the wire rope springs were investigated separately as well as combination of both modes. In addition, the effect of increasing the spring coil diameter and number of coils on the stiffness and damping ratio values were observed. The system was found to have the same stiffness and damping ratio values regardless of the excitation direction. The roll mode seemed to have no effect on damping ratio when both modes were combined. However, stiffness is the summation of both modes. The overall trends of damping ratio and stiffness are in agreement with prior studies.