Multipoint Wave Measurement in Tuned Liquid Damper Using Laser Doppler Vibrometer and Stepwise Rotating Galvanometer Scanner.

Yoon-Soo Shin,Junhee Kim

doi:10.3390/s21248211

Abstract

Liquid dampers, such as tuned liquid dampers (TLDs), are employed to improve serviceability by reducing wind-affected building vibrations. In order to maximize the vibration suppression efficiency of the liquid damper, the tuning frequency of the liquid damper should match the natural frequency of the building. Experimental evaluation of the tuning frequency of a liquid damper performed in a factory prior to installation in a building is a critical task to ensure correct performance, and for this, multipoint measurement of the TLD is required. In this study, a novel liquid level measurement system combining Laser Doppler Vibrometer (LDV) and a stepwise rotating galvanometer scanner was developed to observe liquid sloshing in TLD. The proposed system can measure the liquid level at multiple points simultaneously with a single laser point. In the experimental phase, the liquid damper’s natural frequency and mode shape are experimentally evaluated utilizing the developed system. The performance of the proposed system was verified by comparison with the video sensing system.

Highlights

Liquid dampers, such as tuned liquid dampers (TLDs), are employed to improve serviceability by reducing wind-affected building vibrations
A tuned mass damper (TMD) is a mechanical device that consists of a spring mass system
To monitor surface motion of liquid in TLDs, a noncontact measurement method utilizing an Laser Doppler Vibrometer (LDV) and a stepwise rotating galvanometer scanner is presented in order to overcome the disadvantages of the single measurement of the conventional contact-type wavemeter and its inability to measure the out-of-plane direction of the noncontact-type video sensor

Summary

Introduction

Liquid dampers, such as tuned liquid dampers (TLDs), are employed to improve serviceability by reducing wind-affected building vibrations. Experimental evaluation of the tuning frequency of a liquid damper performed in a factory prior to installation in a building is a critical task to ensure correct performance, and for this, multipoint measurement of the TLD is required. Energy dissipation technology has been developed to install auxiliary mass dampers to improve the performance of flexible buildings sensitive to earthquake loads and wind [1,2]. Two different configurations of liquid dampers have been investigated: tuned liquid column damper (TLCD) and tuned liquid damper (TLD) These different configurations utilize energy dissipation wave braking/sloshing on free liquid surfaces and liquid motion of oscillating in U-shaped narrow tubes, respectively [10,11]. Unlike the TLCD, where the first oscillating mode is controlled, the first several modes are predominant in the TLD [12]

Methods

Results

Conclusion