The performance of one-dimensional and two-dimensional tuned liquid dampers

摘要

The Tuned Liquid Damper (TLD) is increasingly being used as Dynamic Vibration Absorbers to mitigate resonant motions of structures. They consist of water tanks with a sloshing frequency almost matching the frequency of the mode shape to be suppressed. The efficiency of TLDs can be enhanced by adding internal damping devices to increase their inherent damping. Slat type screens are used throughout this study as they have many practical advantages. The difficulty of designing a TLD arises from its nonlinear response behaviour. The dynamic response of a 1-D TLD equipped with damping screens is first investigated by a series of shake table tests on several scaled TLD models. Results from this experimental study are used to investigate the dynamic response characteristics of the TLD. An equivalent mechanical analog based on an equivalent amplitude dependent Tuned Mass Damper (TMD) is developed to match the experimental results. This equivalent TMD model is subsequently validated by experimental 1-D structure-TLD system tests.;Both linear and nonlinear models are investigated as predictors of the behaviour of TLDs. Both models are capable of simulating the sloshing fluid response of a TLD equipped with damping screens. Shake table tests are conducted to quantify the loss characteristics of the slat screens. The analytical models are then compared with experimental results to verify their limitations.;The first experimental investigation to assess the use of a 2-D TLD for suppressing multidirectional structural motion is presented in the next section. Shake table tests are conducted on two rectangular and one square 2-D TLD tanks to determine if the sloshing responses of a 2-D TLD along its principal directions are coupled. Results from the free surface motion and resulting base shear forces indicate that the responses of a 2-D TLD are uncoupled and can be combined by linear superposition.;The performance of a 2-D structure-TLD is subsequently investigated to demonstrate that the sloshing motion in a 2-D TLD can be represented by the superposition of two independent 1-D TLD systems. The ability to model a 2-D TLD as 2 independent 1-D TLDs is of significant benefit. The 1-D nonlinear model validate earlier is used to model a 2-D TLD. Results indicate that 1-D design theory and models can be applied to 2-D TLD design.;The robustness and efficiency of 1-D and 2-D TLDs for structure-TLD systems excited by random forces is investigated. The findings are of particular importance to the use of such devices to mitigate the wind-induced response of tall buildings. A number of systems are studied and the nonlinear model is validated for different structure-TLD systems. A properly designed TLD is found to operate with high efficiency inside a target range of wind-induced amplitude motions. The efficiency of a TLD remains substantial for motions beyond those of the designated target amplitude motions, indicating the TLD is additionally a robust device.