wind load, types of wind force, calculation of wind load , calculations and example of wind load

2. Calculate wind load on any building
Mahreen Zamir Abro
14ce-16

3. Wind load :
Wind represents masses of air moving mainly horizontally
(parallel to the ground) from an area of high pressure to an area
with low pressure
The main effect of wind is a horizontal loading of buildings
(especially high-rise).This effect of the wind on the structure (i.e.
the response of the structure), depends on the size, shape and
dynamic properties of the structure

4. When the wind enters the building from the windward side and
leeward side is relative closed, internal pressure is developed
that acts like negative pressure Similarly, when high speed wind
passes by a building, it produces a vacuum on the leeward side,
this vacuum results in internal suction producing negative
pressure from the structure Keeping the movements in the
upper levels of the building to acceptable human tolerances is
the goal of the structural engineer

7. Types ofWind Load Forces on Buildings:
Shear Load
Lateral Load
Uplift Load
To assist in your wind loading analysis, use the following
wind load calc to get the necessary wind load calculations.
Accurate wind load calculations will that a safe, durable
structure is assembled

8. Wind Load Calculation :
In order for a structure to be sound and secure, the
foundation, roof, and walls must be strong and wind
resistant.When building a structure it is important to
calculate wind load to ensure that the structure can
withstand high winds, especially if the building is
located in an area known for inclement weather.

9. Calculations :
The generic formula for wind load is Fw = A x P x Cd .
This equation is useful for estimating the wind load on a
specific object, but does not meet building code requirements
for planning new construction.
The simple formula for wind pressure P in imperial units
(pounds per square foot) is P=0.00256V^{2} and the pressure
in SI units (Newtons per square meter) P=0.613V^{2}.

10. Drag is the force that air exerts on the building, affected by the
building's shape, the roughness of its surface, and several other
factors. Engineers typically measure drag directly using
experiments, but for a rough estimate you can look up a typical drag
coefficient for the shape you are measuring. For example:The
standard drag coefficient for a long cylinder tube is 1.2 and for a
short cylinder is 0.8.These apply to antenna tubes found on many
buildings.
The standard coefficient for a flat plate such as the face of a building
is 2.0 for a long flat plate or 1.4 for a shorter flat plate.
The drag coefficient has no units.

11. For example, let’s say you want to determine the wind
load on an antenna that is 3 feet long with a diameter of
0.5 inches in a gust of 70mph win ds. Start by estimating
the projected area.
In this case, A=dw=(3ft)(0.5in)(1ft/12in)=0.125ft^{2}
Calculate the wind
pressure: P=0.00256V^{2}=0.00256(70^{2})=12.5psf}.
For a short cylinder the coefficient of drag is 0.8.
Plugging into the
equation: F=APCd=(0.125ft^{2})(12.5psf)(0.8)=1.25lbs.}
1.25 lbs is the amount of wind load on the antenna