Study Of Multi-modal Wind Induced Vibration Coefficient Of Irregular High-rise Flexible Structure

For high-rise flexible structure, wind load is usually the dominant load. The national structural design code (NSDC) has given a series of computational methods for high-rise structures with regular quality and stiffness distribution. However, for those with irregularly changing stiffness or quality structures, no specific analytical or computational method was issued; only the random vibration theory was recommended in such structural analysis. In engineering practice, however, irregular high-rise structures are widely applied. Every year, there are many high-rise structural damage or even structural collapse due to high speed wind excitation, in which miscalculation of the wind load may be one of the main reason that has caused these accidents.The key point of wind load computation is to determine the wind induced vibration coefficient. Wind can be regarded as the superposition of average wind and fluctuating wind. In practice, to take consideration of the fluctuating wind’s influence, the average wind load is multiplied by an amplification coefficient, namely wind induced vibration coefficient. Therefore, the study of wind induced vibration coefficient of different structures is of great significance.This paper firstly introduces the computational methods of the wind induced vibration coefficient of high-rise flexible structure in relevant design codes. Then random vibration theory method for computing the wind induced vibration coefficient is presented. After that, the procedure of computing multi-modal wind induced vibration coefficient of high-rise flexible structure is summarized, and that computing procedure is programmed using MATLAB. On that basis, the wind induced vibration coefficient of a kind of high-rise flexible structure with a lumped mass is calculated, and the following passage makes a comparison between wind induced vibration coefficient of one mode and that of multi modes. At last, this paper makes an analysis on the collapse of a50meter high-rise structure with irregularly changing stiffness, quality.