The Wind-induced Response And Wind Loads Recognition Of Tall Buildings

Wind load is one of the main design loads of structures. Compared with seismicload, the amplitude of wind load is comparatively small but its occurrences are morefrequent. In recent years, with the trend of tall-buildings becoming taller and moreflexible, the importance of the studies of wind loads and wind-induced responses oftall-buildings has been increasing rapidly. The inverse problem of wind-inducedstructural response is the identification of wind loads on structures by the use of thestructural responses, which is of significance to a deeper understanding of themechanisms of wind loads on tall-buildings, and the structural time-history responseanalysis and the health monitoring of tall-buildings.Combining the wind tunnel test and theoretical analysis, utilizing both thefrequency domain method and the time domain method, a thorough analysis andstudy of the problem of equivalent static wind load, wind-induced response and windload inversion is presented in this thesis, A new method of wind load identificationfor tall buildings is proposed.Through a wind tunnel experiment of a tall building in wind-fields with differentturblulence intensities, this thesis studies the change patterns of equivalent staticwind loads with regard to factors including attacking wind angle, the turbulencelevel of approaching wind and the dynamic characteristics of structures, anddiscusses the influences of these factors on the wind-induce responses such asdynamic amplify coefficient and structure acceleration response, which provides animportant basis for structural wind resistance design.An assumption about the correlation of wind loads and the results of wind tunneltest are used to determine the time-history of the wind loads, and on the basis ofstructural dynamics, the time domain analysis of structures under time-varying windload is carried out and the time history of structural responses of displacement,volecity, and acceleration are calculated.Structural responses and related suppositions of structural wind load are utilized,and according to the self-compiling matlab programs, the normalized statisticalaverage algorithm is adopted to inverse the wind loads of structure with unknownphysical parameters, which retrieves the structure’s wind loads and estimates thestiffness of structure simultaneously. The noise applicability of this method is also assessed and tested. The results show the parameters identification is independent tothe initial value in the absence of noise, the maximum error is less than0.25%, theinversely obtained wind loads are close to the true value. When the noise level of theresponse reachs30%, the error in identification is about8%, the variation of theinversed load is still consistent with the true values.The results presented in this thesis prove that the method is of certain noiseapplicability and it can be applied to the field measurement of wind effects on tallbuildings. Inversing structural wind loads on the basis of field-measuredwind-induced responses paves a new way for structural wind engineering researchand study.