پديد آورندگان :
بخشي، حسين دانشگاه حكيم سبزواري - دانشكده مهندسي - گروه عمران , رخشاني مهر، مهراله دانشگاه الزهرا - دانشكده فني , رامشيني، محمد دانشگاه حكيم سبزواري
كليدواژه :
مدلسازي لايه مرزي اتمسفريك , تونل باد , درصد توربولانس , آئروديناميك در پلان
چكيده فارسي :
پيشرفت دانش مهندسي روش ها و تكنيك هاي جديد در صنعت ساخت، امكان احداث سازه هايي كه به نحو قابل ملاحظه اي سبك، مرتفع و انعطاف پذير باشند را فراهم كرده است. حساسيت چنين سازه هايي در برابر نيروي باد بيشتر از سازه هاي سنتي و كم ارتفاع مي باشد. اصولاً نيروي باد نقش مهم و تعيين كننده اي در طراحي سازه هاي بلند دارد و لازم است در طراحي آن ها اثر باد و نيروهاي حاصل از آن با دقت بيشتري بررسي شود. يكي از پارامترهاي مهم و تاثيرگذار در رفتار تعادلي سازه و احساس آرامش افراد مستقر در سازه، ميزان ارتعاش سازه است كه با درصد توربولانس معرفي مي شود. به دليل وجود تراكم بيشتر پوشش هاي گياهي و سازه هاي پيراموني در نقاط نزديك به زمين، ميزان درصد توربولانس در ارتفاعات پايين بيشتر مي باشد. در اين تحقيق با استفاده از مطالعات قبلي در خصوص شبيه سازي لايه مرزي اتمسفريك هوا در تونل باد، مدلسازي نرم افزاري پروفيل سرعت باد ايجاد شده در اطراف دو ساختمان در حين ساخت- در مراحل مختلف تكميل ديوارهاي جانبي با شكل هاي متفاوت در پلان، انجام و درصد توربولانس توليدشده در اطراف هر دو ساختمان بررسي مي شود. درنهايت مشخص مي شود سازه هايي كه در پلان از خاصيت آئروديناميك بيشتري برخوردارند رفتار بهتري در برابر نيروي باد از خود نشان مي دهند.
چكيده لاتين :
Engineering knowledge Development has provided new methods and techniques in the manufacturing industry, the possibility to construct structures that are considerably lighter, higher and more flexible. The sensitivity of such structures against wind power is more than that of traditional and low level structures. The wind is driving force for many of the phenomena affecting the urban environment, such as indoor and outdoor air, heat transfer, pollution dispersion and air quality. Despite their importance to human life in the cities, however, urban streams are still not fully understood. Basically, wind power has a significant and decisive role in the design of tall structures and the design and analysis of wind effect and its forces are required to be studied more carefully. One of the most important and effective parameters in the equilibrium behavior of structure and the comfort of individuals in it is the vibrations of the structure that is introduced by turbulence percent. Because of the density of surrounding vegetation and structures in areas close to the ground, turbulence percentage is more at low altitudes. Regulations according to geographical location and weather conditions of area has certain definitions on the behavior of tall buildings. In this study, the regulations of the US (America Society of Civil Engineers ASCE2010) is used. In all field studies, wind engineering is an important issue to determine the atmospheric boundary layer flow around the structures. Atmospheric boundary layer is the boundary layer of air on the surface of the earth at a height above the surface, assuming the friction of natural flow of wind ineffective. Air flow is divided into the mainstream and the boundary layer flow (atmospheric). The most important parameter that separates the two streams is liquid-friction (viscosity, fluid friction). Friction in the mainstream s almost negligible. However, in the boundary layer it is very important. Thus, each area, with any area coverage has a different boundary layer height. Many studies have been conducted on new methods and facilities for simulating atmospheric boundary layer. Comparison of velocity profiles generated in the atmospheric boundary layer is an important issue addressed in previous studies. After reaching a suitable environment that ideal regulation conditions in terms of matching the profiles of wind speed obtained with regulation profiles of wind speed, required studies and results such as the percentage of turbulence in this study can be obtained. In this study, by using previous studies results on simulating atmospheric air boundary layer in the wind tunnel, software modeling profiles of wind speed around the two buildings during the build in various stages of side walls completion were created with different shape in plan, and the turbulence percentage generated around both buildings were checked. It is identified that the amount of turbulence in terms of height in buildings during construction increases to a height equivalent to the height of the gradient (height of boundary layer atmospheric) by increasing elevation, vegetation and coverage of the side walls. From this height, due to the exit from the gradient height and reduced barriers to wind such as buildings surrounding the vegetation, this parameter is reduced and at higher altitudes is almost zero. However, at a height equivalent to the height of the wind tunnel, it is shortly increased because of the wind collision with upper surface of wind tunnel. Finally, structures that has more aerodynamic properties in their plan show better behavior against wind power.
