Abstract Summary
High-rise buildings are sensitive to wind-induced vibrations. The occupant comfort under these vibrations is assessed based on the peak acceleration. This peak acceleration is strongly dependent on the natural frequency and the damping of the building. Bronkhorst and Geurts showed that the damping and natural frequencies determined in the design phase of high-rise buildings can deviate significantly from measured values. Previous studies have investigated the influence of soil-structure interaction (SSI) on the damping of high-rise buildings, and observed that the overall damping is significantly influenced by soft soils. However, these studies did not explicitly account for the wind loading and applied a simplified analytical modelling approach for the foundation without consideration of piles. Furthermore, they did not investigate the influence of SSI on the peak acceleration under wind loading. In-situ measurements of both wind loads and building accelerations on the residential tower New Orleans (Rotterdam, the Netherlands), provided a good basis to investigate the influence of SSI on the dynamic behaviour of a high-rise building under wind loads. In the research presented here, a model was developed which consists of a frequency dependent description of the pile foundation, the building and the wind load. The dynamic spring stiffnesses of the foundation were obtained with a boundary element method software (Dynapile 2016). The building was modelled as a section-wise Euler-Bernoulli beam; the section bending stiffnesses were obtained with a detailed FEM model of the New Orleans tower. The Power Spectral Density function of the wind loading was obtained from wind load measurements. Finally the dynamic response is computed through the solution of the system of stochastic differential equations in the frequency domain. The results show that the spectral model accurately predicts the measured dynamic response of the New Orleans tower in the along-wind direction. For all the examined dynamic properties (natural frequency, damping and peak acceleration), the error compared with the measurements was smaller than 7%. A comparison with results obtained following the guidelines in EN.1991.1.4 showed a 30%–35% underestimation of the peak acceleration. The guidelines EN.1991.1.4 overestimate the natural frequency and the overall damping of the New Orleans tower, which results in an underestimation of the peak acceleration. More results on the influence of SSI on the dynamic properties will be presented in the full paper. The full paper will provide a more in-depth discussion of the comparison with the original design calculations and the calculations with the currently applicable design code (EN.1991.1.4). Finally, an additional model, will be studied. This model includes, in a simplified manner, the effects of SSI on the natural frequency and modal damping, to the Eurocode procedure. The results of this research show that the EN.1991.1.4 guidelines result in an underestimation of the peak acceleration compared to measurements on the New Orleans tower. In the full paper it will be demonstrated that soil-structure interaction plays an important role in obtaining a better estimate for the peak acceleration.
