في هندسة الرياح، تستخدم اختبارات نفق الرياح لقياس السرعة حولها، والقوى أو الضغوط
على الهياكل.المباني العالية جدا، والمباني ذات الأشكال غير عادية أو معقدة
(مثل مبنى برجي شاهق مع منحني مكافئ أو شكل القطعي)
،مثل كابل الجسور المعلقة
يتم تحليل الجسور والأبنية العالية في حدود يشابه الغلاف الجوي
ومنطقة تأثير الأبنية المجاورة على سرعة وشدة الرياح
ضمن أنفاق الرياح المتخصصة. لتمثيل دقيق لسرعة الرياح والاضطراب
وتأثيره على بناء الهيكل.
وذلك بعد عمل ماكيت و مجسمات نموذجية بمقياس
مطابق او مصغر تشابه وتطابق الهيكل الحقيقي
حيث توفر اختبارات نفق الرياح قياسات ومعرفة قوى وشدة الضغط
على المبنى البرجي اللازمة للتصميم
في استخدام التحليل الديناميكي والسيطرة على المباني العالية
من تأثيرات دفع ا لرياح وتقليل او منع انتقال وانحراف وتشوه البناء
Wind engineering testing
In Wind Engineering, wind tunnel tests are used to measure the velocity around, and forces or pressures upon structures. Very tall buildings, buildings with unusual or complicated shapes (such as a tall building with a parabolic or a hyperbolic shape), cable suspension bridges or cable stayed bridges are analyzed in specialized atmospheric boundary layer wind tunnels. These feature a long upwind section to accurately represent the wind speed and turbulence profile acting on the structure. Wind tunnel tests provide the necessary design pressure measurements in use of the dynamic analysis and control of tall buildings
Thank U
Dr. Hammida
3. 3
Some engineering codes should be required to conduct
Wind tunnel experiment
The miniature replicas models within the test tunnel
In case of higher construction design Tower - and skyscrapers
When the requirements and the constitutions of account
The effect of the distribution of the forces of wind and
Pressure Simplified and approximate given that code does
not permit application
4. 4
Wind engineering testing
In Wind Engineering, wind tunnel tests are used to measure the velocity
around, and forces or pressures upon structures. Very tall buildings, buildings
with unusual or complicated shapes (such as a tall building with a parabolic or a
hyperbolic shape), cable suspension bridges or cable stayed bridges are analyzed
in specialized atmospheric boundary layer wind tunnels. These feature a long
upwind section to accurately represent the wind speed and turbulence profile
acting on the structure. Wind tunnel tests provide the necessary design pressure
measurements in use of the dynamic analysis and control of tall buildings
Thank U
Dr. Hammida
7. 7
-إلى سرعتها تصل رياح مقاتلة وبدل خليفة برج في022كلم/يخدعوا أن قرروا التصميم وفريق بيل فان ،ساعة
الرياح.متوقع غير تصميما خليفة لبرج أعطوا لكنهم ومستطيال مسطحا البرج يكن لم.ليحرف مصمم البرج في قسم كل
الدوا قوة يضعف وهذا ،مختلفة بصورة الرياحالهوائية العاصفة قوة ويكسر مات.
-،هائال اختالفا أحدث وهذا المبنى حول وحركتها الرياح هبوب وكيفية الريح نصمم الحقيقة في كنا ،المبنى صممنا عندما
هذا نفعل لم لو االرتفاع هذا إلى لنصل نكن ولم.
1:50 scale model of top of Burj Dubai building, in NRC's 9m x
9m wind tunnel.
Modelling the Burj Dubai Tower
- Designed by Skidmore, Owings and Merrill, the spire atop the tower is
planned to reach a height that exceeds 750 meters (2,460 feet), and the
tower will have 164 floors.
- For its own tests, RWDI had built a model of the entire tower at a scale
of 1:500, and performed the tests at a relatively low Reynolds number.
8. 8
For the NRC tests, RWDI provided a 1:50 scale model of the top third of
the tower made of balsa wood and aircraft plywood, with all the
external detail carefully crafted. "We then fitted it with surface pressure
transducers," says Dr. Larose. The tests were conducted at high wind
speed, yielding a high Reynolds number.
- researchers can generate the wind conditions that are relevant to each
structure, taking its proportions, design and surrounding terrain into
account. "For the Burj Dubai project, we simulated the turbulent
flow conditions that can occur at high elevation in the Dubai region,"
says Dr. Larose. "Wind at the top of a tall building will be much stronger
than at ground level, but less turbulent."
- How do design engineers use this information? "RWDI used the data to
determine the extent of Reynolds number effects, calculate wind loads
on the structure, and pressure on the surface of the building," says Dr.
Larose. "The results from the NRC and RWDI tests together helped the
design engineers define the required size and strength of the
foundations, what cladding is required on the building, and many other
construction decisions right up to the thickness of the glass at the top of
the tower."
9. 9
- According to Dr. Larose, building codes do not provide all the
information needed to ensure the safety of structures with exceptional
proportions and design. In cases like this, engineers must perform wind
tests before making critical decisions on the materials and dimensions
of the foundation. One of the things they need to be able to predict is
"acceleration" – that is, the rate of change of the back-and-forth
movement at the top of the building.
- Although a building has to be flexible to stay upright in the wind, if
there is too much acceleration, people can get seasick. If wind tunnel
tests show the acceleration is too high, the builder must add "damping"
to the structure, like shock absorbers in cars, to reduce vibrations and
swaying. Large damping devices ― such as a mass rolling on rails ― can
be installed at the top of the building where it counters any back-and-
forth movement and absorbs energy.