EXPERIMENTAL STUDIES ON THE CHARACTERISTICS OF TUNED LIQUID DAMPERS FOR REDUCING VIBRATION IN STRUCTURES

摘要

Traditional design approaches usually consider seismic actions as equivalent static actions. Recent research has shown that adopting a dynamic approach where the real characteristics of seismic actions are taken into account may lead to reach significant behavior improvements. The inclusion of energy dissipation passive devices is nowadays seen as an effective way of improving structures protection towards seismic actions. A significant number of this kind of devices is already placed in real structures all over the world. Vibration mitigation of the seismic actions imposed to the structures is being more and more taken into account in structures design. In order to get more effective systems, structure's designers are using more and more passive devices. Systems like Tuned Liquid Dampers (TLDs) have drawn some attention to the scientific and designing community as an effective, easy to implement and economic solution for vibration mitigation. In order to validate TLDs properties a 3.7 ton one degree of freedom transmission system with adjustable dynamic characteristics has been developed to simulate structures natural frequencies between 0.7 and 2 Hz. The variation of frequency in the referred range is achieved by means of a system of air-springs placed in the transmission system. The present paper reports the results of experimental tests made on the air springs in order to characterize them as well as develop a model which rules its mechanical behaviour and that will be very useful for the definition of the characteristics of the transmission system and its response to dynamic actions. Furthermore dynamic tests performed over TLDs to characterize its behaviour and validate theoretical models are described and the corresponding preliminary results presented. This work aims at preparing the testing device to perform parametric studies in order to evaluate the dynamic characteristic of the transmission system with and without TLDs included and its performance for each situation. This paper also describes the equipment and instrumentation used during the experimental programme performed..