A307 anchor bolts are ideal for where ductility and economy are priorities, but ultra-high strength is not required.
A307 bolts are unless specified. For anchor bolts, corrosion is a frequent failure mode.
The anchor bolt is a critical load-transfer component in structural engineering, connecting structural elements to concrete foundations. Among the various grades available, the bolt (specifically Grade A) occupies a unique and often misunderstood niche. While higher-strength bolts (e.g., F1554 Grade 55 or 105, A325, A490) are common for moment-resisting and high-tension applications, A307 remains the standard for low-strength, ductile, and cost-effective anchorage. This paper defines the material properties, appropriate applications, critical limitations, and inspection criteria for A307 anchor bolts in accordance with IBC, ACI 318, and OSHA standards. a307 anchor bolt
| Property | Value | | :--- | :--- | | | 60 ksi (414 MPa) minimum | | Yield Strength | 36 ksi (248 MPa) minimum (typical, not mandatory by ASTM but implied by material) | | Elongation | 18% minimum (in 8 in.) – High ductility | | Hardness | Brinell 100–241 | | Threads | UNC series (Class 1A or 2A) | | Material | Low-carbon steel (e.g., A36, 1018) |
The ASTM A307 anchor bolt is not a “lesser” product—it is an product for specific roles. Its high ductility (18% elongation) exceeds that of higher-strength bolts, making it valuable for connections requiring plastic deformation without fracture. However, engineers must resist the temptation to “upgrade” to A307 for simplicity. For seismic, high-tension, or cyclic loading, F1554 Grade 55 or Grade 105 is required. When used correctly—embedded in concrete for light structural or non-structural anchorage—the A307 bolt provides safe, reliable, and economical service for decades. A307 anchor bolts are ideal for where ductility
Do not use mechanically galvanized or electroplated coatings for embedded anchor bolts—hydrogen embrittlement risk is elevated for low-carbon bolts.
| Environment | Required Protection | | :--- | :--- | | | As-rolled (plain) acceptable | | Exterior, moderate | Hot-dip galvanized per ASTM A153 (minimum 2.0 oz/ft²) | | Coastal/marine | Stainless steel (Type 304 or 316) – A307 spec does not apply; use F1554 | | Embedded in concrete | No coating required (alkaline passivation) – but cutoff must be above ground | The anchor bolt is a critical load-transfer component
Using AISC 360 and ACI 318-19, the nominal steel strength of an A307 anchor bolt in tension is: