Structural failure is the collapse or breakdown of a structure or structural element when the applied load exceeds its load-bearing capacity. During failure, the element loses its ability to carry loads, which can result in deformation, fracture or total collapse.
Types of failure
- Flexural failure — a beam or slab breaks when bending forces become too great
- Shear failure — the material ruptures due to a transverse force
- Buckling — a slender column or strut suddenly deflects sideways under compressive load
- Punching shear — a column punches through a flat slab
- Fatigue — repeated cyclic loading eventually causes fracture, even below the ultimate strength
Limit states
Structural design distinguishes two limit states:
- Ultimate limit state (ULS) — the point at which the structure is on the verge of failure. Design checks include partial safety factors
- Serviceability limit state (SLS) — deflection or cracking becomes unacceptable, but the structure does not collapse
Application
The concept of structural failure is essential in:
- Structural design — every structure is designed against failure using safety factors
- Inspection and maintenance — signs of impending failure (cracks, excessive deflection) are monitored
- Forensic investigation — after a collapse, the cause of failure is determined
Related terms
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