Masonry Headed Anchor Bolt Tension (TMS 402 ASD)
The allowable tension of a headed anchor bolt in grouted masonry.
Example
You enter
- Masonry strength f'm (psi) 1500
- Effective embedment lb (in) 4
- Bolt effective tensile area Ab (in², net: 1/2 in 0.142, 3/4 in 0.334) 0.334
- Bolt yield fy (psi, A307 = 36000) 36000
You get
- Masonry breakout Bab 2,433 lb
- Steel Bas 7,214 lb
- Allowable tension Ba 2,433 lb (masonry breakout governs)
Checked against published worked examples from: NCMA / CMHA.
Details, formula, and sources
ScopeThe anchor that fastens a ledger or sill to a CMU wall. TMS 402 allowable-stress design takes the lesser of masonry breakout Bab = 1.25 x Apt x sqrt(f'm), with Apt = pi x lbe^2 the projected breakout cone, and steel Bas = 0.6 x Ab x fy. A 3/4 in anchor (effective tensile area Ab = 0.334 in^2, NCMA TEK 12-03C; Fy 36 ksi) embedded 4 in in 1,500 psi masonry gives Bab = 2,433 lb and Bas = 7,214 lb, so masonry breakout governs at 2,433 lb; double the embedment to 8 in and Bab rises to 9,733 lb, so now the 7,214 lb steel governs. Edge distance reduces Apt; shear (pryout) is a separate check. A design aid, not a substitute for the engineer of record's stamped design.
Formula or tableApt = pi x lbe^2; Bab = 1.25 x Apt x sqrt(f'm) (masonry breakout, ASD); Bas = 0.6 x Ab x fy (steel); Ba = min(Bab, Bas).
Source and editionTMS 402 (Building Code Requirements for Masonry Structures) allowable-stress anchor-bolt tension provisions, as compiled in the Masonry Designers' Guide and CMHA TEK notes, by name.
Free accessCMHA TEK notes on anchor-bolt design are free public CMHA technical notes; the 1.25 x Apt x sqrt(f'm) and 0.6 x Ab x fy arithmetic is public.
What governsEstimate. AHJ and licensed professional govern.
API field namesfm_psi, lbe_in, ab_in2, fy_psi, bab_lb, bas_lb, ba_lb
- Lesser of two modes the allowable is the lesser of masonry breakout Bab = 1.25 x Apt x sqrt(f'm) and steel Bas = 0.6 x Ab x fyTMS 402 ASD
- Full-cone projected area Apt = pi x lbe^2 assumes a full breakout cone; edge distance or overlapping cones reduce AptTMS 402
- Tension only axial tension only; anchor shear (pryout) and combined shear-tension are separate checksTMS 402