In construction, engineers employ shear keys in diverse structures to bolster resistance against lateral forces, such as those induced by earthquakes and sliding pressures. These keys find application in a variety of scenarios, including bridges, retaining walls, residential building basements, precast constructions, culverts, masonry walls in seismic regions, and steel columns.
Shear keys can be crafted from concrete in precast constructions or residential building basements. Alternatively, they may be manufactured from steel, especially in instances like steel column base plates. Occasionally, steel reinforcement steps in to perform the role of a shear key, as seen between basement walls and footings.
Shear keys serve diverse functions within structures, such as sacrificial roles in bridges or impeding the movement of distinct components in precast structures. In essence, shear keys play a crucial role in enhancing the overall stability of structures.
The primary objective of shear keys is to offer resistance against lateral forces, encompassing earth and water pressures, seismic events, and wind-induced pressures.
Different structures require shear keys to counter specific forces, including shear forces, lateral forces, and earth pressure. Let’s delve into the functions and positions of shear keys in various structures:
Shear keys are strategically positioned in the abutments of small to medium-sized bridges to furnish lateral transverse support to the superstructure under lateral loads. They play a pivotal role in resisting seismic loads during strong earthquakes. There are two types of shear keys in bridge structures: exterior and interior shear keys, each with its merits and demerits.
Shear keys are incorporated at the base of retaining walls to enhance sliding resistance. Placement beneath the stem of the retaining wall is convenient, simplifying reinforcement placement. The shear key should be proportioned considering width and depth to ensure strength against shear forces.
Shear keys are integrated at the joint between the footing and basement wall. The construction involves casting the shear key as part of the wall extending into the keyway or groove formed in the footing. Different forms of shear keys, including combinations with reinforcing bars, are employed for structural integrity.
Special shear keys, like blocks of I-stub or T-section, are used at the base of columns to resist shear
Shear keys are utilized in precast constructions to connect separate precast components and augment shear resistivity at joint surfaces.
In seismic regions, masonry blocks are equipped with shear keys during manufacturing to resist out-of-plane forces between adjacent blocks during earthquakes. This proactive approach enhances the seismic resilience of masonry structures.
By understanding the purpose and functions of shear keys in different structures, engineers can make informed decisions to fortify their constructions against various lateral forces and ensure long-term stability.