What is wind terrain category? Types wind terrain categories as per standards?

Terrain is the one of the most important factor in building design and it is related to the wind load type under lateral loading condition. This type of load is comes under the lateral loading condition. The speed of the wind is depending upon the terrain category in building design. The complete concept of the terrain is explained in IS 875-part 3 code provisions. The terrain is purely depends upon the height of the obstacles and roughness of the surface or ground.

Types of wind terrain categories

The wind terrains are classified into four types as per IS code standards.

Terrain category 1

Terrain category 2

Terrain category 3

Terrain category 4

Wind Terrain category 1

This is the first one in wind terrain category. Under this category the height of the obstacle or trees or other types are less than 1.5 meter.

The building constructions in open space or grass land or 1.5 meter less obstacles are some of the examples under this type. The building construction in open space like open ground or obstructions free area are comes under this case.

Wind Terrain category 2

This is the second in the wind terrain. Under this type the normal height of obstacle or trees or other types are in between 1.5 meter to 10 meter.  The scattered obstructions are taken under this type as per IS code standards.

The building construction under 1.5 meter to 10 meter height obstacles with spaced objects like single storey structures and plants comes under this type of category.

Wind Terrain category 3

This is the third type in the wind terrain category. Under this case the number of closely spaced obstructions which is having the building height up to 10 meter from bottom of the earth with or without less number of closely spaced objects is considered.

Wind Terrain category 4

This is the last type of terrain as per the IS 875 part 3 code provisions. Under this type the closely spaced obstructions with the height of the buildings greater than 10m are considered. The buildings in city are comes under the terrain category 4 are the perfect examples in this type.

The complete concepts related to the wind terrain are explained in my YouTube channel Civil Engineering by Shravan please see the complete details in below video.

Conclusions of wind terrain category and Types wind terrain categories as per standards

Well now the above explained concepts are related to wind terrain and types of wind terrain as per the IS 875 part 3 code provisions. As per the code terrains are classified in to four types which are related to the terrain 1, terrain 2, terrain 3 and terrain 4. The height of the obstacle or trees or other types are less than 1.5 meter are considered as terrain 1, the normal height of obstacle or trees or other types are in between 1.5 meter to 10 meter comes under terrain 2, the number of closely spaced obstructions which is having the building height up to 10 meter comes under terrain 3, and the closely spaced obstructions with the height of the buildings greater than 10m are considered in terrain 4.

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