Single-Shear Bolted / Dowel Lateral Design Value (NDS Yield-Limit Z)
How much lateral load one bolt, or one lag screw entered by its root diameter, through two wood members carries.
Example
You enter
- Bolt diameter D, or a lag screw's root diameter Dr (1/4 to 1 in; a 3/8 in lag is 0.265) 0.5
- Main-member bearing length lm (in; for a lag, the penetration less the tapered tip) 3.5
- Side-member bearing length ls (in) 1.5
- Main-member specific gravity Gm 0.5
- Side-member specific gravity Gs 0.5
- Bolt bending yield Fyb (psi) 45000
You get
- Mode Im 2,450 lb
- Mode Is 1,050 lb
- Mode II 913 lb
- Mode IIIm 1,103 lb
- Mode IIIs 615 lb
- Mode IV 716 lb
- Z (lb) 614.841
Checked against published worked examples from: American Wood Council; American Wood Council (AWC).
Details, formula, and sources
ScopeFrom the NDS European yield model: all six single-shear yield modes (Im, Is, II, IIIm, IIIs, IV) computed from the dowel bearing strengths, the bolt bending yield, and the geometry, with the governing Z the smallest. A 1/2 in bolt into a thin side member almost always governs in mode IIIs. The reference value before the CD / CM / Cg / geometry adjustment factors, which the user applies. A design aid, not a substitute for the engineer of record.
Formula or tableFe|| = 11,200 G; Fe_perp = 6,100 G^1.45 / sqrt(D); Hankinson blend to theta; Re = Fem/Fes; Rt = lm/ls; Ktheta = 1 + 0.25(theta/90); the six single-shear yield modes Z_Im..Z_IV of Table 12.3.1A; Z = min of the six.
Source and editionNDS Table 12.3.1A single-shear yield-limit equations, the 12.3.3 dowel bearing strengths, and the Table 12.3.1B reduction terms, by name.
Free accessThe yield-limit equations, dowel bearing strengths, and reduction terms are published in NDS Chapter 12 (AWC, free read-only at awc.org); the arithmetic is public.
What governsEstimate. AHJ and licensed professional govern.
API field namesd_in, lm_in, ls_in, gm, gs, fyb_psi, z_im, z_is, z_ii, z_iiim, z_iiis, z_iv, z_lb
- Governing mode Z is the smallest of the six single-shear yield modes; a bolt into a thin side member usually governs in mode IIIsNDS Table 12.3.1A
- Reference value only Z is before the CD / CM / Ct / Cg / C_delta / Ceg adjustment factors and any group / row multiplication; the user applies thoseNDS Table 11.3.1
- Bolt band the 1/4 to 1 in diameter band selects the (4, 3.6, 3.2) bolt reduction terms and excludes small-dowel nails / screws and the geometry / spacing checksNDS Table 12.3.1B