How the masonry shear wall calculator works
This free masonry shear wall calculator checks a reinforced concrete masonry (CMU) wall resisting in-plane lateral load, such as a story shear from wind, using TMS 402-16 strength design, the edition referenced by the Florida Building Code, 8th Edition (2023). Enter the wall length and height, jamb and distributed vertical bars, horizontal bond-beam bars, grouting, f'm, the lateral force and the gravity loads, and the checks update as you type.
What it checks
- In-plane flexure with axial load from a strain-compatibility interaction diagram (εmu = 0.0025, 0.80f'm stress block), checked with each end of the wall in compression
- In-plane shear: Vn = (Vnm + Vns)γg, with Vnm = [4.0 − 1.75(Mu/Vudv)]An√f'm + 0.25Pu and Vns = 0.5(Av/s)fydv, limited to the maximum Vn
- Sliding at the base by shear friction (§9.3.6.5)
- Axial compression with the slenderness reduction of TMS 402-16 Eq. 9-11
- Maximum vertical reinforcement for information, and a φPn–φMn interaction diagram with the load points
Method
The wall is divided into 8 in. cells. Cells with vertical bars are grouted and act over the full thickness; ungrouted cells carry compression on their two face shells only. Bars in compression are neglected because they are not laterally tied, which is conservative. For each load combination the neutral axis is found so that the internal forces balance the factored axial load, which gives the nominal moment strength at that load.
Loads follow the ASCE 7-22 strength combinations 0.9D + 1.0W, 1.2D + 1.0W + L + 0.5Lr, 1.2D + 1.6Lr + 0.5W and 1.2D + 1.6L + 0.5Lr, with the wall's own weight added. The base moment is V·hv for a cantilever wall and V·hv/2 for a pier fixed at both ends.
Assumptions and limitations
- One rectangular wall segment in running bond with a single curtain of vertical bars and concentric gravity load. Flanged walls and walls with openings are not covered; check each pier separately.
- Wind and other non-seismic in-plane loads. Seismic detailing for intermediate or special reinforced walls, boundary elements and capacity-design shear are not checked.
- Story drift and out-of-plane loads are not checked. Use the masonry wall calculator for out-of-plane design.
- Wall weight is estimated from typical unit densities unless you enter it.
Frequently asked questions
Why is 0.9D + 1.0W usually the governing combination?
Axial compression adds to the flexural strength of a lightly loaded shear wall and to its sliding resistance. The combination with the least dead load, minus any wind uplift, therefore gives the lowest capacity for the same lateral force.
What is γg in the shear equation?
TMS 402-16 multiplies the shear strength of partially grouted shear walls by γg = 0.75 because tests show they are weaker in shear than fully grouted walls. Fully grouted walls use γg = 1.0.
Why does the calculator ignore vertical bars in compression?
TMS 402 does not count reinforcement in compression unless it is laterally tied like column reinforcement. Typical wall bars are not tied, so only the masonry carries compression.
How do I model a wall that spans several stories?
Enter the total base shear as V and the height of the resultant lateral force as hv, so that V·hv equals the base overturning moment. Use the full wall height for h, which sets the slenderness reduction.
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For educational and preliminary design purposes only. Always verify results with a licensed PE.