بهینه سازی آیرودینامیک ساختمان های بسیار بلند و ارزیابی کارآیی آن

To improve safety and serviceability of super-tall buildings in strong winds, aerodynamic optimization of building shapes is considered to be the most efficient approach. Aerodynamic optimization is aimed at solving the problem from the source in contrast to structural optimization which is aimed at increasing the structural resistance against winds. However, there are two challenges that usually limit the applicability of aerodynamic optimization in design practice. One is a potential conflict between optimization schemes and other design aspects, and another is a potential conflict between cost and effectiveness. To minimize these conflicts, it is important to conduct aerodynamic studies in early design stage to gain reasonable assessment on various optimization options. This paper summarizes the aerodynamic approaches that have been used with success in building designs, and discusses the principles and effectiveness of these approaches. To provide a guideline for preliminary design, this paper proposes a practical approach to assess the effectiveness of tapering, twisting and stepping, the three common schemes of aerodynamic optimization in super-tall building design.

For super-tall building designs, engineers have to respond to challenges of wind issues. Due to high slenderness, low natural frequencies, low inherent damping levels and high wind speeds at upper level, super-tall buildings are susceptible to wind excitations, particularly to vortex-induced oscillations. From design point of view, not only the wind loads, the wind-induced building motions are also within the scope of design to ensure building’s serviceability. It is well known that the behavior of wind response is largely determined by building shapes. Considerations regarding aerodynamic optimization of building shapes in early architectural design stage is proved to be the most efficient way to achieve in wind-resistant design. Wind-resistant design and aerodynamic optimization are the modern topics in building design community. However, its practice and successful example can be traced back a long time ago. In ancient China, tall buildings appear to be those of traditional pagodas. Some of them even meet the modern definition of slenderness for super-talls.

Aerodynamic optimization of building shapes is an important portion of super-tall building design. Two categories of optimization are discussed in the paper: aerodynamic modifications that are normally considered as remedial measures; and aerodynamic designs that integrate architectural designwith aerodynamic study in the early design stage. While aerodynamic modifications mostly involve building corner treatments, aerodynamic designs have more options in building shapes, including overall elevation optimizations such as tapering, twisting, stepping, opening, top sculpturing, etc. A few examples of aerodynamic optimization schemes that have been implemented with success in building designs are illustrated in this paper.