Active Vibration Control of Bridge Tower Under Construction

Abstract

In large structures such as towers of suspension bridges or cable-stayed bridges, we often need to suppress the wind-induced vibration for their safety. Especially in the construction stage, the structures are more flexible than the completed ones. This paper discusses the active dampers used to suppress the wind-induced vibration of a tower of a suspension bridge (The Kurushima Bridge 3P Tower) during the construction. The active damper was used to suppress the wind-induced vibration in multiple modes predicted by wind-tunnel test. The controller design of the dampers is based on an H∞ robust control theory. At each erection step, we measured the dynamic properties of the towers to adjust the parameters of the controller using the active dampers as vibration exciters. The measured dynamic properties of the active controlled structures are compared with those of a non-controlled structure. The analysis of free vibration shows the suppression performance of active damper as expected in the controller design.