Loadbearing capacity

In construction, a loadbearing element (sometimes called a ‘bearing’ element), such as a structural wall, is an active structural part of a building. Typically, it carries and transfers dead or imposed loads down into the foundations. Loadbearing walls are often constructed from high strength materials such as brick, block or concrete.

Loadbearing capacity is the maximum ability of a structural member or material to take loading before failure occurs. For example, before the onset of unacceptable bending.

The opposite of a loadbearing structural member is one that is non-loadbearing and which only carries its own weight, such as a non-loadbearing partition. Typically, these elements can be removed or repositioned relatively easily since they carry no loads and so will not affect the stability of a structure. However, some elements that are generally considered to be non-loadbearing, such as cladding panels, may be affected by dynamic loads, such as wind loading which can cause deflection or suction failure.

In loadbearing construction, applied loads (dead, imposed and dynamic) are distributed in a variety of ways, including through walls, columns, beams, slabs etc. The builders of the large Gothic cathedrals invented a novel way to increase the loadbearing capacity of the external walls which may otherwise have been pushed outwards by the enormous lateral forces exerted on them by the roof vaults. The problem was solved by the addition of flying buttresses which relieved the loads from the external walls and conveyed forces from the roof into the ground.

The loadbearing capacity of an element of structure can be influenced by:

• Size – a thick wall can take higher loads than a thinner wall of similar material and construction. A tall concrete-block wall may be more prone to buckling than one which is a quarter of its height and of identical material, construction and loading.
• Density – dense materials such as stone and concrete are more able to resist failure under loading compared to materials such as aerated blocks.
• Material properties such as density, compressive strength, resistance to shear forces, bending, vibration and so on.
• Structural design – by virtue of its shape. For example, a folded-plate roof may be able to accept higher loads than one that is a simple flat slab. Similarly, a diagonally-braced structure will have a higher loadbearing capacity (and therefore be more rigid) than an identical structure that is unbraced.
• Environmental conditions such as temperature, fire, frost, moisture and so on.

[edit] Related articles on Designing Buildings

• Arches.
• Bearing capacity.
• Bending moment.
• Biaxial bending.
• Braced frame.
• Concept structural design of buildings.
• Concrete-steel composite structures.
• Dead loads.
• Elastic limit.
• Elements of structure in buildings.
• Floor loading.
• Force.
• Lateral loads.
• Live loads.
• Load bearing.
• Load-bearing wall.
• Long span roof.
• Moment.
• Point of contraflexure.
• Shear force.
• Shear wall.
• Stiffness.
• Subsidence.
• Supported wall.
• Uniformly Distributed Load.