No description available.

No description available.

No description available.

The study is concerned with developing an adequate Performance-Based Wind Engineering (PBWE) framework for tall building design. The focus is to introduce advanced modelling and simulation techniques to improve key analysis stages, namely by using Computational Fluid Dynamics (CFD) and Computational Structural Mechanics (CSM). The clearly defined five stage PBWE framework is realised and implemented using both existing and newly developed simulation components. The performance of the developed process is explored by comparative PBWE analyses to assess the wind-induced behaviour of two tall building designs with distinctly different cross sections; a regular rectangular cross section and an irregular „L‟-shaped cross section. The performance of CFD was primarily dependent on the turbulence model. On the basis of an extensive validation study, the Reynolds-Averaged Navier-Stokes (RANS) model was able to adequately compute the mean pressure coefficients acting on the benchmark CAARC tall building. However, its inability to sustain the atmospheric turbulence resulted in a significant under-estimation of the top floor accelerations. Hence, it was concluded that the RANS model is not suitable for competent PBWE studies. The results showed that the Large Eddy Simulation (LES) model offered the closest alternative to wind tunnel testing. However, full LES was too computationally expensive to be used for the PBWE framework, and hence a hybrid RANS-LES simulation strategy was formulated as a compromise. This was considered to offer an appropriate representation of the wind-induced pressure field without prohibitive complexities emanating from a full LES model. The response of the regular tall building was compared for both the RANS and the LES computed wind loads. This identified that the atmospheric turbulence had a much greater affect on the response of a regular prismatic tall building than the structure-induced turbulence. Despite an increase in structure-induced turbulence, the results suggested that the response of an irregular L‟-shaped tall building would also be governed by atmospheric turbulence in the incident wind field.

No description available.

Wind action is particularly important for tall buildings, both in providing a significant contribution to the dynamic overall loading on the structure and by affecting its serviceability. Whereas low and medium-rise buildings are fairly rigid, tall structures are characterized by a greater flexibility and a lower natural frequency, which is more likely to be in the frequency range of wind gusts. In addition, wake effects, such as vortex shedding, can become a significant problem for flexible structures when the vortex shedding frequency is close to the natural frequency of the building. The aim of the present thesis is to assess the validity of commercial CFD codes for modelling the wind flow around a high-rise building, including the consideration of the coupled dynamic response of the building to turbulent wind loading. Three intermediate objectives are set. The first is to develop a tool to couple fluid and structure in a sequential manner. The equations for the air flow are solved using the commercial CFD program ANSYS-Fluent. The response of the structure is found from solving the structural response with a modal approach, the response in each vibration mode being treated as a SDOF problem. This fluid-structure interaction tool is applied to model a 180 m building, allowed to move in the across wind direction. The second objective is to investigate and find a method to generate fully turbulent inflow for LES in order to reproduce an accurate wind spectrum. The chosen method is tested and validated in an empty fetch. Ultimately, both tools are brought together and applied to model a 180 m building, which is allowed to bend in the along wind and across wind directions. Finally, the third intermediate objective brings together the tools developed in the first and second intermediate objective to model the dynamic response of a 180 m building to dynamic wind loading, within a turbulent inflow, using LES.