Modal Parameter Identification Of Super Tall Buildings Under Ambient Wind Excitation

In recent years,with the acceleration of urban modernization,a large number of super tall buildings have been built in the southeast coastal area in China.These super tall buildings have the characteristics of light weight,high flexibility and low damping,resulting in horizontal and torsional wind-induced response of their main structure under the action of typhoons,which affects structural safety.Traditional structural modal parameter identification methods are usually based on stationary assumption.However,the measured dynamic responses of super tall buildings under environmental excitation usually have non-stationary characteristics,so the traditional methods have limitations.Therefore,how to accurately estimate the structural parameters such as frequency and modal damping by non-stationary signals under environmental excitation is the key and core problem of modal parameter identification.Aiming at the current problems,this paper introduces the latest time-frequency analysis method into the area of modal parameter identification of super high-rise building structures based on environmental wind excitation,and develops three sets of modal parameter identification methods combined with the traditional instantaneous frequency and damping ratio solution methods.Through the modal parameter identification analysis of the numerical model and the structural responses of Taipei 101 and Guangzhou CITIC Plaza under the influence of typhoon,it is verified that the modal parameter identification method proposed in this paper is effective,accurate and applicable to the modal parameter identification of super tall buildings.In addition,an improved Random Decred Technique(RDT)is proposed and applied to analyze the acceleration response of the four-storey frame numerical model and the CITIC Square in Guangzhou.The characteristics of structural damping varying with amplitude are evaluated,and the results clearly reveal the nonline ar energy dissipation characteristics of the structure.