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Understanding Shear Keys in Construction: Their Functions and Applications

The shear keys have been used in the construction structure to enhance the resistance to sliding. The shear is an extension of the vertical stem that extends below the bottom of the base. The shear keys have been installed to enhance the extra passive resistance that has been developed by the height of the shear keys. The shear keys have been developed and used in various structures which helps to provide resistance to the lateral loads including earthquake loads and sliding forces in various structures.

The shear key has been constructed from concrete as in the case of precast construction, or manufactured from steel as in the case of steel column base plate. Steel reinforcement can also be used in the shear keys for instance among footing and basement walls. The shear key helps to prevent the movement of different components of structure thus helping to improve the overall stability of the construction structure.

In the foundation structure, the shear keys have been provided to carry the shear forces. The shear keys have been placed at the raft foundations. Based on the nature of the construction process, Waterstops have been provided in the foundations. The Waterstops have been placed at the center of the foundation or the bottom of the foundation, whereas, the water bars have been placed in the case of there are movement joints.

Applications of Shear Keys in various Construction Structures

The shear forces have been applied in different structures to resist certain forces including lateral forces, shear forces and earth pressure. There are different functions and positions of shear keys in various structures, which are as follows:

Retaining walls

At the base of the retaining wall, shear keys have been provided to enhance the sliding resistance. The placement of the shear keys under the stem of the retaining wall helps to simplify the placement of the reinforcement which can also be extended from the stem into the other stem.

Bridge structure

In the case of the abutments to the small to medium-sized bridge structure, shear keys can be placed to provide lateral transverse support to the superstructure under the lateral loads. In the bridge structure, the shear key also plays a crucial role in resisting seismic loads.

Footing-basement wall

The shear key has been also provided at the joint among the footings and the basement walls. The shear key has been cast as the part of the wall which extends into the groove or keyway that formed into the footing. The upturned shear key has been cast as part of the footing which is not usually used in residential work. The reinforcement bars can be provided to resist bending, this is the reason, bars can be used as the replacement of the shear key.

Steel column base and footing joint

A special shear key has been installed at the bottom of the steel column base plate. This type of shear key helps to resist the shear forces at the base of the column.

Masonry wall

The masonry blocks have been equipped along with the shear keys in the seismic regions during the manufacturing process. This helps to resist the out-of-plane forces among the adjacent blocks during the incidents of the earthquake.

Precast concrete elements

In the precast construction, shear keys have been also used to connect two separate precast components. This is also effective in increasing the shear resistivity of the surface of the joints.

Partitions

The vicinity shear key can also be needed at the bottom of keeping partitions which have been placed just beneath the stem. In this case, the shear key helps to prevent sliding of the bottom at some point of the utility of the strong lateral force.

Applied in beams

The shear keys have been provided for the slab on the basis of the span of the slab and the loads that have been applied to the slab. If there is no larger span in the slab, the shear key can be avoided.

Applied in slabs

The shear keys have been placed in the beams in a similar manner to the slab. Most of the time, shear dowels have been placed in the beam construction joints.

Functions of the shear keys in column

The shear keys have been provided to the column to provide a mechanical connection among the two adjacent structural elements with the help of a ley-shaped groove and corresponding projection. This mechanical connection helps to prevent sliding or other related movement among the components which helps to increase the overall stability of the structure as well as helps to transfer the structural burden.

Lateral forces resistance

The primary function of the shear key is to resist the shear or lateral forces. The shear key helps to provide additional stability against the horizontal movements that have occurred by wind loading, earthquakes and the displacement of the soil.

Transferring loads

The transmission of the loads has been facilitated by the shear keys among the adjacent structural elements including beams, walls, columns and foundations. The shear key helps to make a strong connection which helps to ensure that the applied forces have been transmitted as well as distributed effectively among the connected elements.

Displacement reduction

The shear key helps to limit the movement or displacement of the structural components in the meantime of dynamic events which helps to reduce the structural damage as well as helps to preserve the structural integrity of the construction structure.