Shear wall

A shear wall is an element of a structurally engineered system that is designed to resist in-plane lateral forces, typically wind and seismic loads.

A shear wall resists loads parallel to the plane of the wall. Collectors, also known as drag members, transfer the diaphragm shear to shear walls and other vertical elements of the seismic-force-resisting system. Shear walls are typically made of light framed or braced wood sheathed in shear-resisting material such as plywood or other structurally rigid panels, reinforced concrete, reinforced masonry, or steel plates.

While plywood is the conventional material used in wood (timber) shear walls, advances in technology and modern building methods have produced prefabricated options such as sheet steel and steel-backed shear panels used for narrow walls bracketing an opening that have proven to provide stronger seismic resistance.

In many jurisdictions, the International Building Code and International Residential Code govern the design of shear walls.

A shear wall is stiffer in its principal X and Y axes than it is in its Z axis. It is considered as a primary structure which provides relatively stiff resistance to vertical and horizontal forces acting in its plane. Under this combined loading condition, a shear wall develops compatible axial, shear, torsional and flexural strains, resulting in a complicated internal stress distribution. In this way, loads are transferred vertically to the building's foundation. Therefore, there are four critical failure mechanisms; as shown in Figure 1. The factors determining the failure mechanism include geometry, loading, material properties, restraint, and construction. Shear walls may also be constructed using light-gauge steel diagonal bracing members tied to collector and ancor points.

The slenderness ratio of a wall is defined as the ratio of its effective height divided its effective thickness. It is highly related to the slenderness limit that is the cut-off between elements being classed "slender" or "stocky". Slender walls are vulnerable to buckling failure modes, including Euler in-plane buckling due to axial compression, Euler out-of-plane buckling due to axial compression and lateral torsional buckling due to bending moment. In the design process, structural engineers need to consider all these failure modes to ensure that the wall design is safe under various kinds of possible loading conditions.

In actual structural systems, the shear walls may function as a coupled system instead of isolated walls depending on their arrangements and connections. Two neighboring wall panels can be considered coupled when the interface transfers longitudinal shear to resist the deformation mode. This stress arises whenever a section experiences a flexural or restrained warping stress and its magnitude is dependent on the stiffness of the coupling element. Depending on this stiffness, the performance of a coupled section will fall between that of an ideal uniform element of similar gross plan cross-section and the combined performance of the independent component parts. Another advantage of coupling is that it enhances the overall flexural stiffness dis-proportionally to shear stiffness, resulting in smaller shear deformation.

The location of a shear wall significantly affects the building function, such as natural ventilation and daylighting performance. The performance requirements vary for buildings of different functions.