Earthquake resistant means that a structure is designed and built to withstand the forces of an earthquake without collapsing. An earthquake-resistant building is not indestructible, but it is engineered to protect the safety of its occupants and limit structural damage during seismic activity.
Why build earthquake resistant?
In seismically active regions, building codes require structures to meet specific earthquake resistance standards. In Europe, Eurocode 8 (EN 1998) sets out the seismic design requirements for buildings. In the United States, the International Building Code (IBC) governs seismic design, with stricter requirements in high-risk zones like California.
Even in areas with low natural seismic activity — such as the Groningen province in the Netherlands, where gas extraction causes induced earthquakes — earthquake-resistant construction has become a requirement.
Principles of earthquake-resistant construction
Structural measures
- Reinforcement — Additional steel reinforcement in walls, floors and foundations absorbs the tensile forces generated by earthquakes
- Ring beams — Reinforced concrete beams on top of walls distribute forces evenly across the structure
- Expansion joints — Separation joints allow different parts of a building to move independently
- Lightweight materials — The lighter the building, the less mass is set in motion during a quake
Foundation
A solid foundation is critical:
- Raft foundation — A single continuous concrete slab that supports the entire building and moves as one unit
- Pile foundation — Piles driven down to a load-bearing soil layer, with a rigid concrete slab on top
Building shape
- Symmetrical floor plans — Square or rectangular buildings distribute forces more evenly than L-shaped or irregular structures
- Low-rise construction — Lower buildings are more stable under horizontal loads
- Rigid connections — All structural elements must be securely connected to one another
Retrofitting existing buildings
Older buildings in earthquake zones can be strengthened with:
- Steel frames added to the inside of walls
- Additional reinforcement in masonry walls
- Carbon fibre strips bonded to the masonry
- New foundations constructed beneath existing structures
Related terms
- Reinforcement
- Foundation
- Concrete
- Ring beam
- Expansion joint
- Structural steel
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