چکیده:
رفتارشناسی باد در اطراف ساختمان‌های بلند به‌عنوان یکی از مباحث بسیار مهم در طراحی معماری و طراحی سازه شناخته می‌شود. هدف از انجام این پژوهش، بررسی تکنیک‌های آئرودینامیکی و بهینه‌سازی فرم در ساختمان‌های بلند برای کاهش نیروی پسا بود.برای شبیه‌سازی دینامیک سیالات محاسباتی و تونل باد از نرم‌افزار Autodesk Flow Design 2014 بهره‌گیری شد. این شبیه سازی بر روی 29 مدل ساختمانی که با تکنیک‌های آئرودینامیکی طراحی شده بودند انجام شد. تکنیک‌های آئرودینامیکی به دو صورت اصلاحات آئرودینامیکی شامل پخ زدن، نرم کردن و دندانه‌دار کردن و همین‌طور فرم‌های آئرودینامیکی نیز شامل مخروطی، عقب‌نشینی و پیچشی بودند که بر روی اشکال با سطح مقطع مربع، مثلث و دایره مدل‌سازی شدند. یافته‌ها نشان داد برای طراحی ساختمان‌های حدود 150 متر، شکل پایه مثلث با اصلاح آئرودینامیکی پخ خورده و با فرم آئرودینامیکی مخروطی می‌تواند دارای کمترین میزان ضریب پسا و همین‌طور بهترین رفتار آئرودینامیکی را در برابر نیروی باد داشته باشد.
چکیده انگلیسی:
Aerodynamic behavior is an important characteristic of tall and ductile buildings, so aerodynamic design can play a key role in reducing the wind effects. A tall building response to wind can be controlled by application of aerodynamic improvements to building’s design in order to manipulate the wind flow pattern and break the effective wind force acting on the structure. Traditionally the approach of structural engineers to mitigating wind loading and associated deflections and motions on tall buildings was to stiffen the building with the aim of increasing the natural frequency. Tall buildings are extremely sensitive to the wind. Thus, assessment of wind loads to design these buildings is essential. Monitoring the wind, which is forcing extraordinary tall buildings, is highly challenging. Due to increasing construction in recent decades, the study on wind flow over tall buildings has become a popular subject in theoretical research and applied engineering applications. By looking at recent constructions in Iran, it is obvious that despite the fact that constructing tall buildings is spreading, there is less concentration on environmental factors such as the wind’s aerodynamic. In tall buildings, aerodynamic behavior generally becomes important. The wind-induced building response of tall buildings can be reduced by means of aerodynamic from design and modifications that change the flow pattern around the building or break up the wind affecting the building face. Aerodynamic-based design can be divided into two types, “aerodynamic architectural design” and “aerodynamic architectural modifications” and their subgroups. The accurate estimation of the critical response parameters, such as top floor accelerations and displacements, is of fundamental importance when ensuring reliable designs of tall buildings. Methods to this end are typically set in a modal analysis framework and therefore require the estimation of the generalized forcing functions. Tall buildings are particularly prone to dynamic excitations such as those from natural disasters like strong winds and earthquakes, and this has become an especially important design issue. One way to minimize wind-induced vibrations of tall buildings is to focus more on their shapes in the design stage. Investigated aerodynamic forces and wind pressures acting on tall buildings with various unconventional configurations. The proposed of this research, investigation of aerodynamic shape optimization on tall buildings in order to reduce drag force. The aerodynamic forms such as a set-back, tapered and helical (twisted) and also aerodynamic modifications such as a chamfered corner, rounded corner and recessed corner to control and reduce wind forces and vortices on tall buildings are considered. On this basis, the study was carried out with numerical simulation of wind tunnel test on 29 building models. In order to construct 3D models, AutoCAD 2014 software was deployed and also to numerically simulate wind tunnel Autodesk Flow Design 2014 is used. Building samples were entered into the software via format FBX. The results showed that for a tall building with a triangular footprint and height of about 150 meters, base shape with chamfered corners of aerodynamic modification and tapered of aerodynamic form can have the best aerodynamic behavior against wind forces.
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