The PPT gives some basic ideas regarding the effects of wind on low rise structures, the forces acting on it with future scope.

1. Wind Effects on
Low Rise Structures
M Gokul (19MCD1016)

2. Introduction:
 Normally wind is one of the criteria for the design of the
structure.
 Due to the effect of the wind on structure, it may lead to the
failure of the structure.

3. Nature of Wind and Pressure
• The variation with height depends primarily on the terrain conditions.
• The magnitude of fluctuating components of the wind speed which is
called gust depends on the average time.

4. Wind Effect on Structures
 It was found that destruction of the cladding is often the beginning of
structure failure and inhabitant injury during an extreme wind event.
 Thus, for the structure’s design, along with other loads, wind load must
also be considered.
 When a building is subjected to wind load, then wind load has mainly
two components:
1. drag force
2. lift force (both may be positive or
negative wind pressures)

5. Wind Effect on High Structures (Cont..)
Geometry of building has a significant effect on distribution of wind pressure on
surface of roof and walls of building.

6. Wind Effect on Low Rise Structures (Cont..)

7. Geometry of Building and Significant Effect on
Low Rise Building:
 Low-rise is a building that is only a few stories tall or any building
that is -shorter than a high- structure, i.e. structure is below 18 -
20 meters.
 Height is based on American wind code and Indian wind code,
respectively(ASCE/SEI: 7-10 2010; IS 875(Part 3) : 2015 2015).
 Strength requirement is a dominant factor.

8. Forces Acting on Building:
• Lift Force:
An lift force is any upward pressure applied to a structure that has the potential
to raise it relative to its surroundings. Uplift forces can be a consequence of
pressure from the ground below, wind, surface water, and so on.
• Drag Force:
1. Drag force used to increase in surge and heave reactions.
2. The influence of the current drag is determined by the extent of the wave energy
spectrum.

9. Basic Flow Direction
1. Windward: The face of the building which is located in the direction of
blowing wind is called windward
2. Leeward: The face of the building which is located on the opposite side
of windward side in the building is called leeward side.

10. Flow Pattern around Building:
Roof Pitch at 15 degree
Roof Pitch at 15 degree
Roof Pitch at 15 degree

11. Pressures on Building:
 Positive Pressure:
The positive pressure acts on the windward direction and therefore the
positive pressure is pushing the building.
 Negative Pressure:
I. The leeward pressure is assumed as negative, as it is opposite in action in
windward side.
II. Hence, the negative pressure in the leeward side pulls the building.

12. Conclusion:
• Wind Engineering has increasingly focused on the modest low rise structure, since
much of the damage and financial loss associated with extreme wind events
happens to these minimally engineered buildings.
• A face perpendicular to the wind direction will have the higher pressure
coefficients as compared to the pressure coefficients on parallel faces.
• It is also noticeable that when the joint of two faces is perpendicular to the wind
direction, then the whole roof surface will have low wind pressure.
• When there are openings in a building, the wind pressure distribution on walls
and roof are significantly affected.

13. Future Scope:

14. Thank You