ACI 318
Building Code Requirements for Structural Concrete and Commentary
The structural design and construction rules for reinforced concrete buildings in the United States, adopted by reference into the building codes that actually carry legal force.
Who needs it
Structural engineers, plan reviewers, special inspectors, and contractors building anything more structural than residential flatwork.
What the test involves
It covers analysis and design of concrete members, reinforcement detailing, anchorage, seismic provisions, and construction and inspection requirements. It also establishes the durability framework that ties a project's environment to its mix requirements through exposure categories — freezing and thawing, sulfate, contact with water, and corrosion protection of reinforcement — each with severity classes such as F0 through F3. A published commentary explains the reasoning behind the provisions, which is often more useful to a contractor than the code text itself.
Common misconceptions
- ACI 318 is not itself law. It becomes enforceable when a jurisdiction adopts a building code that references a specific edition, and which edition applies varies by location.
- Exposure classes are assigned from the environment the concrete will actually live in, not from the building type — an interior slab and an exterior stair on the same project can land in different classes.
- Meeting the specified strength does not mean meeting the durability requirements. A mix can hit its psi and still be non-compliant for its exposure.
Official source
We summarize scope and purpose only. The full text belongs to the issuing body — read it at the official source. American Concrete Institute