Field measurements of dynamic properties of high-rise buildings

Field measurement techniques, including ambient wind excitation, crane excitation, synchronised human excitation and mechanical shaker methods, commonly employed to measure the dynamic properties of high-rise buildings are presented. The instrumentation, test methodology, merits and limitations of these techniques, including a purpose-built computer-based mechanical shaker, are discussed. The dynamic properties of four residential buildings in Hong Kong ranging in height from 130 m to 256 m were determined using these field measurement techniques. The results show that the dynamic properties, including natural frequencies of vibration, damping values, and deflected mode shapes can be accurately determined. These measured dynamic properties are compared with values suggested by wind load standards, empirical predictors and computed values from finite element models. The measured natural frequencies were found to be in good agreement with the Japanese empirical predictor of 67 divided by building height, attributable in part to the design requirements in both regions to resist typhoon loading.