Reinforced CMU Shear Wall In-Plane Shear (TMS 402 ASD)

The masonry term Fvm = 0.5 x ((4.0 - 1.75 M/(V dv)) sqrt(f'm)) + 0.25 P/An that grows with axial compression and shrinks with slenderness, the horizontal-steel term Fvs = 0.5 Av Fs dv/(An s), and the combined stress against the shear-span-graded 3-to-2 sqrt(f'm) cap, times the net area for the allowable force. An 8 in by 8 ft wall under 20 kip of axial with #4 horizontals at 48 in carries 76 psi and 55.7 kip -- the capacity the seismic base-shear demand is checked against. Sustained axial only; special-reinforced detailing is separate. A design aid, not a substitute for the engineer of record's stamped lateral design.

Fvm = 0.5 x ((4.0 - 1.75 x M/(V dv)) x sqrt(f'm)) + 0.25 x (P/An); Fvs = 0.5 x (Av Fs dv)/(An s); Fv = Fvm + Fvs, capped at 3 sqrt(f'm) (M/(V dv) <= 0.25) grading to 2 sqrt(f'm) (>= 1.0); Va = Fv An.

TMS 402-16 (ACI 530 / ASCE 5) allowable-stress in-plane shear provisions, as compiled in the Masonry Designers' Guide and CMHA TEK 14-07C, by name.

CMHA TEK notes on shear-wall allowable-stress design are free public CMHA technical notes; the Fvm / Fvs arithmetic is public.

Estimate. AHJ and licensed professional govern.

Field names used by the API: fm_psi, b_in, dv_in, p_lb, mvd, av_in2, s_in, fs_psi, an_in2, fvm, fvs, fv, fv_max, va_kip

• Two contributions plus a cap the masonry diagonal-tension term (raised by axial compression, lowered by slenderness) plus the horizontal-steel term, with the combined stress capped on the shear-span-graded 3-to-2 sqrt(f'm) lineTMS 402-16
• Sustained axial only P is the sustained compression acting with the shear; do not count live load that may be absent when the lateral force arrivesTMS 402-16 / Masonry Designers' Guide
• Detailing separate special-reinforced shear-wall detailing, minimum reinforcement ratios, and the shear-friction base check are separate code requirementsTMS 402-16