What is Shear Wall?

What is a Shear Wall?

Shear wall is a structural member used to resist lateral forces i.e. parallel to the plane of the wall such as wind and seismic loads. Many young engineers are able to answer this much. They know that a shear wall needs to provide lateral load resistance. This is absolutely right. However still that is not a complete understanding of what a shear wall is. For slender walls where the bending deformation is more, Shear wall resists the loads due to Cantilever Action. In other words, Shear walls are vertical elements of the horizontal force resisting system.

Exact Definition?

All RC walls are not shear walls. It needs to behave as a shear wall to call it a shear wall. Shear wall meaning is not some thing that can be defined. There is no clear definition in IS 456 or even in IS 1893. However, American codes tie it to the sway and also give a rough thumb rule based on the stiffness of wall to that of all columns put together. If the stiffness or the inertia of wall is many times more than that of the columns put together, then it qualifies as a shear wall.

Many consultants also check the bending in the wall and if it’s behaving as vertical cantilever, then consider it as a shear wall.

Position of a shear wall?

Ideal position of a shear wall should be carefully decided in larger projects. If the Center of lateral mass coincides with the Center of stiffness, the building won’t be subjected to torsion, when the ground moves. A wrong stiffness concentration around corner of a building may lead to undesirable torsion in the building during earthquakes. The position needs to be finalized based on careful analysis. Structurally, the best position for the shear walls is in the center of each half of the building. This is rarely practical, since it also utilizes the space a lot, so they are positioned at the ends. It is better to use walls with no openings in them. So, usually, the walls around lift shafts and stairwells are used. Also, walls on the sides of buildings that have no windows can be used.

Shear wall design similar to columns?

Shear wall is a vertical member carrying all forces similar to columns. The lateral shear will be much higher. Though the design procedure is interactive as in columns, there are many other careful considerations that needs to be adopted for shear wall design.

Importance?

Shear walls are especially important in high-rise buildings subject to lateral wind and seismic forces. Generally, shear walls are either plane or flanged in section, while core walls consist of channel sections. They also provide adequate strength and stiffness to control lateral displacements. The shape and plan position of the shear wall influences the behavior of the structure considerably.