Shear strength
Shear is a type of stress in which an applied force causes a structure to 'slide' in two or more directions. Shear can cause a structural member to split vertically or diagonally. For example, a cantilever beam built into a wall may shear at the point of support due either to its own weight or the applied forces, or both.
Shear strength is the ability of a material or component to resist shear forces without failing or, put another way, the maximum shear force that can be accommodated before failing.
Shear strength is analogous to ultimate tensile strength (UTS). The difference is that in shear the strain is parallel to the face (or cross-section) of the element in question whereas tensile strain is at right angles.
In structures, knowing the shear strength of materials is critical to be able to design or specify structural components (e.g beams, plates, bolts etc) economically whilst still withstanding shear forces.
In timber, shear strength tends to be affected by the direction of loading in relation to the grain. The shear strength tends to be around 10-15% of its tensile strength (in the direction of the grain). But shear strength will be reduced by the presence of knots, cracks and faults.
Adhesives tend to have high shear strengths. This can be measured by bonding two strips together then pulling them apart under a constant load. Typically, an epoxy resin adhesive can have shear strengths in the region of 26MPa, however, this is an idealised test and in use the shear strength of an adhesive can depend on many variables including surface preparation, conditions and so on.
Bolts can have a critical function in structures, for example, if they are used to connect a steel frame together or fix steel beams to a concrete core. In such instances, bolts may be required to withstand significant shear forces.
Typical shear strengths include:
In soil mechanics, the shear strength of soil is the shear force which can be sustained by the soil. This is dependent on numerous variables such as the friction between particles and the degree of interlock between them, whether they are cemented together or bonded at contact surfaces and so on.
Determining the shear strength of a cohesionless soil can be achieved by using either a direct shear test or a box shear test. Using the direct shear method allows the cohesion and angle of internal friction of soil to be established, which can be useful in the engineering design of elements such as foundations and retaining walls.
The direct shear test can be applied to the following soil conditions:
- Unconsolidated-undrained.
- Consolidated-undrained.
- Consolidated-drained.
See also: Shear.
[edit] Related articles on Designing Buildings Wiki
Featured articles and news
The benefits of engaging with insulation manufacturers
When considering ground floor constructions.
Lighting Industry endorses Blueprint for Electrification
The Lighting Industry Association fully supports the ECA Blueprint as a timely, urgent call to action.
BSRIA Sentinel Clerk of Works Training Case Study
Strengthening expertise to enhance service delivery with integrated cutting-edge industry knowledge.
Impact report from the Supply Chain Sustainability School
Free sustainability skills, training and support delivered to thousands of UK companies to help cut carbon.
The Building Safety Forum at the Installershow 2025
With speakers confirmed for 24 June as part of Building Safety Week.
The UK’s largest air pollution campaign.
Future Homes Standard, now includes solar, but what else?
Will the new standard, due to in the Autumn, go far enough in terms of performance ?
BSRIA Briefing: Cleaner Air, Better tomorrow
A look back at issues relating to inside and outside air quality, discussed during the BSRIA briefing in 2023.
Restoring Abbotsford's hothouse
Bringing the writer Walter Scott's garden to life.
Reflections on the spending review with CIAT.
Retired firefighter cycles world to raise Grenfell funds
Leaving on 14 June 2025 Stephen will raise money for youth and schools through the Grenfell Foundation.
Key points for construction at a glance with industry reactions.
Functionality, visibility and sustainability
The simpler approach to specification.
Architects, architecture, buildings, and inspiration in film
The close ties between makers and the movies, with our long list of suggested viewing.
SELECT three-point plan for action issued to MSPs
Call for Scottish regulation, green skills and recognition of electrotechnical industry as part of a manifesto for Scottish Parliamentary elections.
UCEM becomes the University of the Built Environment
Major milestone in its 106-year history, follows recent merger with London School of Architecture (LSE).
Professional practical experience for Architects in training
The long process to transform the nature of education and professional practical experience in the Architecture profession following recent reports.