Where do you put a shear key?

Shear keys are provided at the base of retaining walls to increase its sliding resistance. Practically, it is convenient to place the shear key beneath the stem of the retaining wall because it simplifies the placement of reinforcement that can be extended from the stem directly into the stem.

What is shear key in retaining wall?

Shear key is a structural element which is sometimes used in the footing of retaining walls to reduce wall’s sliding. The shear key sides are vertical which continue all along the wall. The soil mass behind and below the wall is dry and cohesionless.

How do you check the shear on a retaining wall?

In essence the shear strength depends strongly on the effective height d of the section, but also on the concrete class fck and the rate of tensile longitudinal reinforcement to deflection ρl = Asl /bw ∙ d.

Why shear key is provided in column?

When structure is failing in Sliding criteria during the stability check due to large horizontal forces on the column , Shear key is provided during construction joint of column to stop the sliding of column from joint there by increasing factor of safety for sliding.

How do I increase the resistance of my sliding retaining wall?

When the friction plus passive forces are not high enough to counteract the pushing force, a shear key can be designed under the wall footing. This structural element will bear laterally against the soil, increasing the sliding resistance.

What are cantilever retaining wall shear keys used for?

Reinforced concrete cantilever retaining walls bearing on soil usually have a shear key incorporated into their footing base. The intended function of the key is to increase the sliding resistance of the wall. A study of the efficiency of shear keys and their location on the footing (toe, stem, or heel) was performed.

What is the function of a shear key in retaining wall How does it help against sliding?

Shear key is provided to increase the resistance to sliding. The shear key is generally an extension of the vertical stem and extends below the bottom of the base. The main purpose of the installation of shear keys is to increase the extra passive resistance developed by the height of shear keys.

What is the role of shear strength in designing the foundation and retaining wall?

When a shear key is installed at the base of the retaining wall, the failure surface is changed from the wall base/soil horizontal plane to a plane within foundation soil. Therefore, the friction angle mobilized in this case is p instead of 0.8p in the previous case and the sliding resistance can be enhanced.

What is a shear check?

A shear test is designed to apply stress to a test sample so that it experiences a sliding failure along a plane that is parallel to the forces applied.

What is maximum height limit of cantilever wall?

Cantilever retaining walls are found best up to a height of 6m. For greater heights earth pressure due to retained fill will be higher due to lever arm effect, higher moments are produced at base, which leads to higher section for stability design as well as structural design.

What is shear key?

The shear key is a part of the structural element mostly used to make the structure stable against the lateral loads. Depending on the type of construction and nature of the loading, the application of shear is different. Mostly the shear keys are constructed between two structural elements.

What is the function of the shear key?

Where to place the shear key on a retaining wall?

Practically, it is convenient to place the shear key beneath the stem of the retaining wall because it simplifies the placement of reinforcement that can be extended from the stem directly into the stem.

What is a shear key in a basement?

Shear keys are provided at the joint between footing and basement wall. The shear key is cast as part of the wall extending into the keyway or groove formed in the footing. Different forms of shear key at the joint between footing and basement wall are shown in Fig-3.

What are the different types of shear keys in bridge structure?

There are two types of shear keys in bridge structure: exterior and interior shear keys. The former has the demerit of the ease of inspection and repair. 2. Retaining Walls Shear keys are provided at the base of retaining walls to increase its sliding resistance.

When to use shear key for footings?

The use of shear key is required when one can not get F.S. against sliding which is a common problem when the base of footing has waterproofing membrane or tanking of concrete with epoxy paint etc. Consider the the steps of construction, for a shallow key conforming the requirements, you should provide a recess at binding concrete .