What is load-bearing capacity?
Load-bearing capacity is the maximum load or weight that a structure, building element or subsoil can carry before failure or unacceptable deformation occurs. It is expressed in kilonewtons (kN), kilograms (kg) or as load per area (kN/m²).
What determines load-bearing capacity?
Load-bearing capacity depends on:
- Material properties — compressive, tensile and bending strength
- Geometry — thickness, width, height and span
- Connections — joints between elements
- Subsoil — for foundations, soil quality is decisive
Applications
The concept of load-bearing capacity plays a role in virtually every structural design problem:
- Floors — a residential floor must be able to carry at least 1.5 kN/m² (≈ 150 kg/m²)
- Piles — a concrete pile can have a load-bearing capacity of 500–2000 kN
- Foundations — the soil must be able to absorb the building load
- Beams and joists — steel profiles are selected based on capacity and deflection
Calculation
Load-bearing capacity is determined using limit-state calculations according to the Eurocode. The calculation takes into account:
- Permanent loads — self-weight of the structure
- Variable loads — people, furniture, snow, wind
- Accidental loads — fire, earthquake, impact
- Safety factors — to allow for uncertainties in material and load
Distinctions
- Design load-bearing capacity — calculated value including safety factor
- Characteristic value — average strength from tests
- Failure load — the point at which the structure fails
Related terms
- Load
- Failure
- Structure
- Eurocode
- Foundation
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