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Title

CONSIDERING THE FORM OF TALL BUILDINGS TO ACHIEVE MINIMUM STRUCTURAL WEIGHT REGARDING ALONG WIND EFFECT

Creator

Alaghmandan, Matin

Date

2014, 2014-07

Description

One of the most influential parameters in structural design of tall buildings, in addition to gravity loads, is the lateral load resulting...
Show moreOne of the most influential parameters in structural design of tall buildings, in addition to gravity loads, is the lateral load resulting from wind and to some extend earthquakes. Tall buildings have to be designed for a larger base shear, resulting from wind forces rather than from seismic forces; however, ductile detailing is used when needed to account for seismic demands. The wind effect occurs primarily in two main modes of action: across wind and along wind. Wind also produces three different types of effects on tall buildings: static, dynamic, and aerodynamic. Structurally, static effect is measured independent of time, while dynamic analysis takes into account the system responses to the changes through the period of time. When the building is flexible, it interacts with the wind load and affects its response, which is called aerodynamic effect. To reduce the static and dynamic impact, there are two main solutions: Architectural and Structural. Architects can mitigate wind effect on tall buildings by designing the form aerodynamically or at least by utilizing aerodynamic modifications, which are categorized in macro and micro modifications such as tapering and setback. Structural engineers can reduce wind effect by choosing and designing efficient structural systems regarding the form of the buildings such as tube systems and diagrid system. This thesis, by utilizing the architectural and structural strategies to reduce wind effect, introduces a new design method in the realm of tall buildings. An innovative design method of tall buildings calls for an integrated approach with considerations for both architectural and structural design requirements and concepts. This design method which considers integrated architectural and structural concepts to reduce the along wind effect, for this particular research, is an effort to achieve the minimum weight of the structure. This method creates an innovative computational workbench to design efficient tall buildings, regarding the along wind effect. This can be achieved by connecting an architectural parametric design procedure in AutoLisp (AutoCAD) to generate the models with different forms of modifications, a Computational Fluid Dynamics program (ANSYS) to do the CFD simulations, a structural analysis program (SAP2000) and the ParaGen visualization interface to consider and compare the results to evaluate the models regarding the criteria such as weight of the structure (ParaGen has also a Genetic Algorithm based optimization procedure that is not used in this research). In this research, the most important architectural and structural parameters of seventy-three of the tallest buildings are also studied. Based on the information gathered, the future trend in the geometry and form and also the structural design used for tall buildings can be predicted. It is necessary to mention, based on the past and current trends in architectural features and structural design of tall buildings, and also the future prediction, the required architectural and structural parameters for an innovative proposed design method can be helped. However, it is not clear whether this trend is in a right way or not, it has to be improved based on the architectural and structural efficient parameters. The research shows that a careful study of core design concepts in architectural features and structural design of tall buildings, along with an integrated approach considering various design requirements, can be an effective method in design of new generation of tall buildings.
Ph.D. in Architecture, July 2014
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