Anchor Bolt Embedment
Required embedment depth of a cast-in headed anchor for a factored uplift.
Example
You enter
- Factored uplift Nua (lb, LRFD) 5000
- Bolt diameter (in) 0.625
- Concrete fc (psi) 3000
You get
- Embedment (in) 2.6635
- Embedment (ft) 0.22196
- T (lb) 5000
No published worked example is on file for this calculation. It is checked against a hand-worked derivation of its method and an independent reference test.
Details, formula, and sources
ScopeFrom ACI 318-19 concrete breakout (hef = [Nua / (0.70 x 1.25 x 24 sqrt(fc))]^(2/3)), cracked or uncracked, with the 1.5 hef edge-distance flag.
Formula or tableACI 318-19 §17.6.2 concrete breakout of a single cast-in headed anchor solved for the embedment: hef = [Nua / (0.70 x psi_c,N x 24 x lambda x sqrt(f'c))]^(2/3), psi_c,N = 1.25 uncracked / 1.0 cracked, Nua the factored tension; the critical edge distance 1.5 x hef is flagged. The inverse of concrete-anchor-breakout. Bolt steel (§17.6.1), pullout (§17.6.3) and code minimum embedments are separate checks.
Source and editionACI 318-19 §17 (Anchoring to Concrete). IBC 2021 (International Building Code). §1908 references ACI 318.
Free accessACI 318 licensed; principles free in published structural texts.
What governsEstimate. AHJ and licensed structural engineer govern.
API field namesuplift_lb, bolt_diameter_in, fc_psi, embedment_in, embedment_ft, T_lb
- Manufacturer ICC-ES report user-supplied for post-installed anchors; required for code complianceICC-ES evaluation reports