Check concrete and stirrup contribution fast for any beam today during design. See capacity, utilization, and pass or fail status for quick review reports.
Enter beam geometry, material strengths, and stirrup details.
Sample inputs and typical output format for quick checking.
| f'c (MPa) | fy (MPa) | bw (mm) | d (mm) | Av (mm^2) | legs | s (mm) | phi | phiVn (kN) |
|---|---|---|---|---|---|---|---|---|
| 28 | 420 | 300 | 500 | 100 | 2 | 150 | 0.75 | ~260 |
| 35 | 500 | 250 | 450 | 126 | 2 | 125 | 0.75 | ~285 |
| 25 | 420 | 350 | 550 | 100 | 4 | 200 | 0.75 | ~380 |
Example outputs are approximate and depend on your entered factor settings.
This calculator applies common reinforced concrete shear capacity components.
Units: MPa for strengths, mm for dimensions, and kN for shear results.
Shear failures in reinforced concrete beams are sudden and brittle, leaving little warning compared with flexural yielding. Construction teams benefit from quick checks confirming whether provided stirrups and section dimensions can safely resist governing shear demand at critical regions.
For common simply supported beams, shear is highest at supports and reduces toward midspan. Continuous beams may show multiple peaks at interior supports. Concentrated loads create steep shear jumps, while uniformly distributed loads create linear shear diagrams. Enter Vu as the factored design shear at the checked section.
Concrete resists part of the shear through aggregate interlock, uncracked compression zones, and dowel action. As compressive strength increases, the square-root trend means gains are steady but not proportional. Raising f’c increases Vc, but gains are not proportional. As a quick reference, many projects specify 25–40 MPa for typical beams, and higher strengths for heavily loaded or durability-driven elements.
Stirrups provide the ductile, controllable portion of shear resistance. Increasing the number of legs or bar size raises total Av, while reducing spacing s increases Vs directly. Halving spacing doubles Vs, often the fastest upgrade option.
Web width bw and effective depth d both scale shear capacity. Wider webs carry more shear and reduce stress concentrations, while deeper beams increase the lever arm and stirrup effectiveness. A 10% increase in d raises both Vc and Vs similarly, so placement accuracy matters.
Normalweight concrete typically uses lambda = 1.00, while lightweight mixes reduce shear capacity through lower aggregate interlock. The lambda option reflects this reduction and encourages closer stirrup detailing.
When Vu is entered, utilization Vu/(phiVn) indicates margin. Values below 1.00 suggest capacity exceeds demand, while values above 1.00 indicate strengthening or redesign is required. Many teams target 0.80 to allow for tolerances and adjustments.
Record the input assumptions, calculated components, and the design strength phiVn in inspection notes, submittals, or RFI responses. The CSV and PDF exports support traceable documentation. They also simplify reviews during inspections, audits, and closeout. Always cross-check with governing project specifications and code requirements for minimum reinforcement and maximum spacing rules.
Vc is the estimated concrete contribution to shear resistance. It depends on concrete strength, a unit weight factor, and beam dimensions, and is added to the stirrup contribution to form total nominal capacity.
Select the phi value required by your design standard for shear. Many reinforced concrete provisions use a lower strength factor for shear than flexure to reflect uncertainty and brittle behavior.
Leave Vu blank to compute capacity only. You can later enter Vu from your structural analysis output to see utilization and a pass or fail result for the checked section.
Total Av equals the entered stirrup area multiplied by the number of legs crossing the shear crack plane. Closed stirrups commonly have two effective legs, while some configurations may have more.
Lightweight concrete generally has lower aggregate interlock, which reduces shear transfer across cracks. The lambda factor accounts for this reduction so the shear estimate is more realistic for the mix type.
This tool assumes vertical stirrups and a simplified approach. If you have inclined bars, unusual loading, or deep beam behavior, use code-specific methods and detailed checks beyond this estimate.
No. Passing indicates estimated design strength exceeds entered demand. Final compliance also requires checks for minimum shear reinforcement, spacing limits, detailing, development, and any additional project or code provisions.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.