Ambient vibration dynamic test and finite element analysis for high-rise buildings

Natural frequencies and modal shapes of high-rise buildings, obtained from on-site ambient vibration test and operational modal analysis, are very important for evaluation of structural dynamic performance and seismic design. In this paper, a dynamic test project of Guangxi Laibin high-rise buildings was introduced. In this project, 8 high-rise buildings were selected for ambient vibration test to obtain the basic time history signals, then the cross correlation function analysis and fast Fourier transform were utilized to generate cross power spectra, from which the modal parameters such as natural frequencies can be obtained by operational modal analysis. Finite element (FE) models were constructed in PKPM and Sap2000 programs to calculate analytical modal frequencies and mode shapes. In order to consider influence of mass and stiffness of the in-filled wall on the dynamic properties of the high-rise buildings, 3 FE models were built in Sap2000 to estimate modal frequencies and modal shapes. It was found that the measured fundamental frequency is twice larger than that obtained from PKPM analysis. In addition, the structural modes obtained from the FE analysis, which uses shell elements to simulate mass and stiffness contribution of the in-filled wall to the corresponding beams, agree well with those obtained from the test. Finally, the frequencies of the 8 high-rise buildings obtained from the tests were compared with those calculated by the empirical equation in 5 countries. ©, 2015, Tumu Gongcheng Xuebao/China Civil Engineering Journal. All right reserved.