ASTM A706/A706M
Standard Specification for Deformed and Plain Low-Alloy Steel Bars for Concrete Reinforcement
Weldable low-alloy rebar with controlled chemistry and controlled ductility, the bar specified for seismic force-resisting systems.
Who needs it
Structural engineers in seismic regions, rebar fabricators, welders, and inspectors on projects with special seismic detailing.
What the test involves
It restricts the chemical composition so the bar can be welded reliably using standard procedures, and it constrains the relationship between actual and specified yield strength so a member fails in the ductile manner the designer intended. That second requirement is the reason it appears in seismic detailing: a bar that is much stronger than assumed can push failure into a brittle mode elsewhere in the member. Bars are marked so the material type is identifiable in the field.
Common misconceptions
- It is not simply 'better rebar.' It is chemistry- and ductility-controlled rebar, and paying for it where the design does not require it buys nothing.
- Substituting carbon-steel bar for specified weldable low-alloy bar is a substitution of a different material, even at the same grade number.
- Being weldable does not mean welding is unrestricted — welding still follows a qualified procedure and is often prohibited at specific locations by the structural drawings.
Official source
We summarize scope and purpose only. The full text belongs to the issuing body — read it at the official source. ASTM International