Masonry Headed Anchor Bolt Tension (TMS 402 ASD)

The 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 (Ab = 0.442 in^2, Fy 36 ksi) embedded 4 in in 1,500 psi masonry gives Bab = 2,433 lb and Bas = 9,547 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 9,547 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.

Apt = 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).

TMS 402 (Building Code Requirements for Masonry Structures, ACI 530 / ASCE 5) allowable-stress anchor-bolt tension provisions, as compiled in the Masonry Designers' Guide and CMHA TEK notes, by name.

CMHA 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.

Estimate. AHJ and licensed professional govern.

Field names used by the API: fm_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