What is Shear ?

Definition of Shear in Construction

Shear is opposing structural forces, which causes slippage, on a plane and failure. A rigid member such as a masonry brick, if half of the brick is experiencing a force down, and the other half of the brick has an opposing force, up, the brick will split in half. Shear is the force that occurs, if a load is laterally projected against an unmovable condition, the shear force will either push through the system and cause failure, or the system will remain static and unmoving. The system has resisted the shear force and was adequately designed to withstand the push.

However, if this force was placed on a column in a parking garage, and the shear force was enough force to cause the column to fail or break, then the shear force would have been more than the system could withstand. In many instances once a shear force causes any type of failure, numerous other stresses, from tensile to bending occur due to the failure caused by the shear force. The shifting of loads and forces within a structure, once part of the structural system, has been compromised and is unpredictable and very difficult to engineer. Due to the immediate and 100% failure that normally occurs if a structural system fails due to a shear force, this type of failure can be catastrophic to the structure.

Shear is an important engineering element when designing a structural system and engineers are constantly designing new methods of distributing shear loads in efforts to limit any concentration of the force. In addition, the engineering of new and stronger synthetic materials, allows the structural systems to be designed both smaller and lighter, to resist the necessary shear forces.