14 Jan 2019

Shear wall

Shear wall
Shear walls

                     Shear wall is a structural member in a reinforced concrete framed structure to resist lateral forces such as wind forces and earthquake forces.

OR                       Shear walls are the resistant element to the horizontal forces acting on it due to severe winds or earthquake.

Structural Mechanism of Shear Wall

                   In concrete buildings construction, a rigid vertical diaphragm capable of transferring lateral forces from exterior walls, floors, and roofs to the foundation in a direction parallel to their planes. Examples are the reinforced-concrete wall or vertical truss. Lateral forces caused by wind and earthquake, and uneven settlement loads. These forces can shear a building apart. Reinforcing a frame by attaching or placing a rigid wall inside it maintains the shape of the frame and prevents rotation at the joints. Shear walls are especially important in high-rise buildings. 
The lateral and gravity load-resisting system consists of reinforced concrete walls and reinforced concrete slabs. Shear walls are the main vertical structural elements with a dual role of resisting both the gravity and lateral loads.
Structural Mechanism of Shear wall

Types of Shear Walls

Based on type of material used, shear walls are classified into following types.
  1. Reinforced Concrete Shear Wall
  2. Concrete Block Shear Wall
  3. Steel Shear Wall
  4. Plywood Shear Wall
  5. Mid-Ply Shear Wall.

1) Reinforced Concrete Shear Wall

Reinforced concrete shear walls are widely used shear walls for residential buildings. The reinforcement is provided in both horizontal and vertical directions. But at the end of each wall, bars are closely spaced and anchored. So, the end zones of RC shear wall is called as boundary elements or barbells.
RC Shear Walls

2) Concrete Block Shear Wall

Concrete block shear walls are constructed using Hollow concrete blocks along with Steel reinforcement bars. Reinforcement is generally used to maximize the effect of concrete block masonry against seismic loads.
RC block Shear Wall

3) Steel Shear Wall

Steel shear wall consists of a steel plate wall, boundary column and horizontal floor beam. The action of steel shear wall is more like a plate girder. Steel plate wall acts as web of plate girder, boundary columns acts as flanges and horizontal beams acts as stiffeners of plate girder.
Steel Shear Wall

4) Plywood Shear Wall

Plywood shear walls are traditional type walls which are also called as timber shear walls. It consists of plywood sheets and studs. Plywood sheets transfer shear force while studs resists the tension or compression.
Plywood Shear Wall

5. Mid-Ply Shear Wall
Mid-ply shear wall is an improved version of normal plywood shear wall. In this case, extra plywood sheet is arranged at the center of normal plywood wall and series of pairs of studs are positioned on the both sides of mid-ply. Studs joint the mid-ply with outer plywood sheets standard shear walls and lateral load carrying capacity is higher for mid-ply shear walls.
Mid-Ply Shear wall
Shear Walls Location in a Building
 Structurally, the best position for the shear walls is in the centre of each half of the building.
Locationof shear walls

Limitation for Shear Walls:

  • Limitations on the use of building,
  • Adverse effects on the behavior of non-load bearing elements,
  • Degradation in the appearance of the building,
  • Discomfort for the occupants.
Generally, the relative lateral deflection in any one storey should not be more than the storey height divided by 500.
Limit for Shear Wall

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