DYNAMIC RESPONSE OF NINE SIMILAR TOWER BLOCKS

Abstract This paper describes an experimental study to determine the variability in natural frequencies and stiffness of nine similar high-rise buildings. Two of the buildings were subjected to forced vibration tests to obtain a comprehensive description of their dynamic characteristics. The response of each of the buildings to wind loading was recorded and analysed to determine their fundamental natural frequencies. A comparison of the natural frequencies shows that the buildings do not have identical characteristics, indeed there is quite a large difference between two of them. This difference is particularly difficult to explain because the buildings are of the same design and were built at the same site using factory precast panels. The difference in characteristics shows that it may never be possible to provide exact calculations of stresses in buildings at the design stage. Several independent engineers were involved in calculating the stresses produced by wind excitation in one of the buildings, and this involved estimating the overall stiffness of the building. These stiffnesses are compared with measurements to further illustrate the likely accuracy of calculations. The implications of these points are discussed.