الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
The analysis of flexible structures under wind load is very difficult and sensitive. The fluctuation of wind load has a great effect on this kind of structures where the structure deflections become more effective. The structure response should be considered simultaneously while calculating the wind load with time throughout the analysis. The typical method to analyze structures under wind load is performed with the aid of the spectral representation method “SRM”, used to generate wind velocity time history, which is used to generate wind pressure. Then, this wind pressure is applied to the structure throughout performing the dynamic analysis. The defect of this approach is that it does not consider the interaction between the generated wind load and the structure deflection. In this thesis an interaction dynamic analysis, proposed by the main supervisor, is introduced. This analysis considers the aeroelastic interaction between the wind and the oscillating structure “the aerodynamic damping”. This aerodynamic damping is very effective in case of flexible structures due to their large deformations. In the present work, a program using Matlab has been developed by the author to generate the wind velocity using the SRM, where the program has been verified through comparison with published results. Then the introduced interaction dynamic analysis has been examined through analyzing plates of several degrees of flexibility under wind load with different levels of turbulence. Moreover this analysis has been evaluated by comparing its results with the CFD “Computational Fluid Dynamics” method results, where good agreement has been obtained.Membrane roof structures have been used for a variety of large-scale structures, such as airports, sports stadiums and shopping malls. These structures are very sensitive to wind load due to their high flexibility and sophisticated geometry that result in susceptible aerodynamic damping. There are two basic stages to analyze these structures. First stage is to find the initial equilibrium configuration of the membrane under a specified prestressing, to achieve its stiffness, through a form-finding process. The updated Reference Strategy (URS) is considered as one of the efficient methods of form-finding analysis. This method has been explained and applied in the present study through Ixforten software. Second stage is to analyze these prestressed membrane structures, after getting their initial shape in the first stage, under wind load using the Computational Fluid Dynamics (CFD) approach through Comsol software.A fully coupled fluid structure dynamic analyses of several saddle membrane roofs have been performed under wind load with different conditions using the CFD method. Through investigating the numerical results of these analyses, the behavior of membrane roofs has been evaluated. It has been cleared that several parameters must be carefully considered in the analysis and design of membrane structures such as the cable sag/span ratio, the membrane sag-span ratio and the membrane initial prestress.