Sample inputs and resulting tension check
| Case | t | L | h | P | M | ft | Tension demand | Allowable | Utilization |
|---|---|---|---|---|---|---|---|---|---|
| Metric | 200 mm | 1000 mm | 3000 mm | 150 kN | 12 kN·m | 0.25 MPa | 1.050 MPa | 0.100 MPa | 10.500 |
| Metric | 150 mm | 800 mm | 2700 mm | 90 kN | 6 kN·m | 0.2 MPa | 1.389 MPa | 0.068 MPa | 20.576 |
| Imperial | 8 in | 36 in | 120 in | 25 kip | 600 kip-in | 29 psi | 1,475.694 psi | 11.600 psi | 127.215 |
Stress from combined axial load and bending
- A = (L · t) · kn
- Z = (L · t² / 6) · kn
- σax = P / A
- σb = M / Z
- σmax = σax + σb (compression side)
- σmin = σax − σb (may become tensile)
- σtension = max(0, −σmin)
Step-by-step workflow for site and design checks
- Select your unit system to match project documents.
- Enter wall thickness and length for the checked section.
- Provide axial load and either moment or eccentricity.
- Choose no-tension or allowable-tension design approach.
- Set material strength and safety/quality factors as required.
- Apply a load factor for the load combination you are checking.
- Review tension demand, allowable, utilization, and warnings.
- Export CSV or PDF to attach with calculations and notes.
Masonry tensile checks for practical wall design
Masonry performs best in compression, yet many real projects introduce small bending effects that create tension at one face of a wall. Common sources include eccentric axial loads, out-of-plumb construction, wind pressure, floor diaphragm drag, openings, and uneven bearing at supports. A masonry tensile check helps you quantify whether those effects remain within an acceptable range for your chosen design approach.
This calculator uses a simplified rectangular wall section to estimate extreme-fiber stress from combined axial load and bending. Axial stress is computed from the factored axial load divided by an effective net area. Bending stress is computed from the factored moment divided by an effective section modulus. The minimum face stress may become negative; when it does, the magnitude represents the tensile stress demand.
In many unreinforced applications, designers adopt a conservative “no-tension” assumption where allowable tension is taken as zero. Where tensile capacity is permitted, an allowable tensile stress can be estimated from the masonry tensile strength reduced by workmanship and section efficiency factors, and divided by a safety factor. The quality factor (kq) can represent joint quality and construction control, while the net factor (kn) reduces capacity for voids or discontinuities. The load factor (LF) lets you run service or factored combinations consistently.
Use the example table as a quick reality check. For instance, a 200 mm thick wall segment with 150 kN axial load and 12 kN·m moment may show little or no tension if compression dominates. Conversely, reducing thickness or increasing eccentricity can raise the tensile demand rapidly because bending stress scales with the square of the thickness through the section modulus. If utilization exceeds 1.0, consider increasing thickness, reducing eccentricity, improving load path alignment, adding reinforcement, or changing boundary conditions.
Treat results as a screening tool: final design should verify stability, slenderness effects, detailing, and governing code requirements for your project’s masonry system and exposure conditions.
Common questions about masonry tension
1) What does “tension demand” mean?
It is the tensile stress at the most critical wall face after combining axial and bending stresses. It becomes nonzero when bending exceeds the compressive axial stress at that face.
2) When should I use no-tension mode?
Use it for conservative checks of unreinforced masonry where the design method assumes masonry carries compression only. If any face tension appears, consider reinforcement or revised loading.
3) Why do kn and kq reduce capacity?
kn reduces effective section properties for voids or discontinuities, while kq represents workmanship and joint quality. Both factors lower the allowable tensile stress to reflect real construction variability.
4) Can I enter eccentricity instead of moment?
Yes. Select the eccentricity option and input e. The calculator converts it using M = P·e in the chosen unit system, then performs the same combined-stress check.
5) Does this replace a full masonry code check?
No. It is a fast screening calculation for combined stress. Final design should include code-specific limits, slenderness and stability checks, reinforcement detailing, and serviceability requirements.
6) What does the allowable moment output represent?
It is the approximate bending moment that would bring the tension at one face to the allowable limit, given the current axial load, factors, and section properties.
7) How should I select tensile strength ft?
Prefer project-specific test data or code-based values for your masonry units and mortar. If unavailable, use conservative typical values and apply appropriate reduction and safety factors.