Research on Mechanism of Collapse by Aero-elastic Instability of a Tall Building

本研究的目的是探讨高层建筑物在发生涡激振动、驰振和扭转颤振等气动弹性失稳时的倒塌过程。为了实现这一目标，风洞试验已经进行了研究，在光滑和湍流中的高层建筑的动力特性，使用传统的万向节振动锁定模式。试验表明，结构阻尼对失稳临界速度和失稳初期的响应影响不大，本文假定建筑物的失稳在初期就伴随着涡的脱落，并假定涡脱落的频率是可以确定的，从而建立了预测上述失稳行为的分析模型通过考虑振动幅度的有效宽度。该模型可以预测风洞试验中的各种动力特性，为研究建筑物失稳时的弹塑性特性，正在研制新的装置。该装置通过反馈力控制平衡环，实现系统中建筑物的弹塑性行为。通过与传统平衡环的失稳响应比较，表明该装置可用于建筑物的弹塑性性能研究。

The objective of this research is to investigate the process of collapse of a tall building by occurrence of an aero-elastic instability like vortex induced vibration, galloping and torsional flutter. In order to achieve the objective, wind tunnel tests have been performed to investigate the dynamic behaviors of tall buildings in smooth and turbulent flows using conventional gimbals vibrating in locking modes. From the tests, the critical velocity of the instability and the response at the initial stage of the instability hardly affected by structural damping, but affected by mass of the building.The analytical model for predicting the above behavior of the instability has been developed by the assumption that any instability of buildings is accompanied by the vortex shedding at the early stage and the frequency of the vortex shedding can be determined by the effective width considering the amplitude of the vibration. The model can predict the various dynamic behaviors in the wind tunnel tests.The new device is developing in order to investigate the elastic-plastic behaviors of the building in the instability. The device can control the gimbals by giving the feed-back force to realize the elastic-plastic behaviors of the building in the system. By the comparison of the response of the instability between the new device and the conventional gimbals, the device can be used in the investigation of the elastic-plastic behaviors of the building.