Free Steel Connection Check Calculator — AISC 360
Check all steel connection limit states in one place: bolt group shear and tension, weld group strength, block shear rupture, shear tab capacity, stiffener requirements, and prying action in end plates. Covers AISC 360-22 Chapter J, AS 4100 Section 9, EN 1993-1-8, and CSA S16 Section 13.
Connection types: single-plate shear tabs, double-angle connections, end-plate moment connections, gusset plates, bracket connections, and splice plates.
How to Use
- Select connection type from the library.
- Enter connection geometry: plate dimensions, bolt layout, weld size and length.
- Specify material properties: Fy and Fu for all plies, bolt grade, weld electrode.
- Apply factored loads: moment, shear, axial at the connection interface.
- Review results: individual utilization ratios for all limit states.
Design Checks Performed
| Limit State | AISC 360 | AS 4100 | EN 1993-1-8 | CSA S16 |
|---|---|---|---|---|
| Bolt shear + bearing | J3.6, J3.10 | Cl 9.3 | Cl 3.6.1 | Cl 13.12 |
| Weld strength | J2.2 | Cl 9.7 | Cl 4.5 | Cl 13.13 |
| Block shear | J4.3 | Cl 9.2.2 | Cl 3.10.2 | Cl 13.11 |
| Prying action | J3.6 | Cl 9.3.2.2 | Cl 6.2.4 | Cl 13.12 |
| Shear tab flexure | J4.5 | Cl 9.3.1 | Cl 6.2 | Cl 13.10 |
| Web local yielding | J10.2 | Cl 5.13 | Cl 6.2.6.2 | Cl 14.3 |
| Web crippling | J10.3 | Cl 5.13 | Cl 6.2.6.3 | Cl 14.3 |
Prying Action Overview
Prying action occurs in tension-loaded bolted connections (such as end plates) where bolt tension induces flexure in the connected plate, amplifying the actual tension demand on the bolts. AISC 360-22 Section J3.6 provides the prying action equations. The key parameters are the plate thickness (tp), bolt gauge (g), and the ratio of flange flexural stiffness to bolt axial stiffness. Increasing plate thickness is the most effective way to reduce prying amplification.
Design Guidance
Key Design Parameters
When performing structural steel design calculations, the following parameters govern the design:
- Material properties: Yield strength (Fy) and tensile strength (Fu) determine section capacity. For US projects, common grades include A992 (Fy=50 ksi) for W-shapes and A36 (Fy=36 ksi) for angles and plates.
- Design method: LRFD (Load and Resistance Factor Design) or ASD (Allowable Stress Design). LRFD applies load factors >1.0 and resistance factors <1.0 for consistent reliability across limit states.
- Load combinations: Per ASCE 7-22, the governing combination depends on the direction and magnitude of each load type. Typically 1.2D + 1.6L governs for gravity-dominated cases.
- Limit states: Strength (ultimate) and serviceability (deflection, vibration). Both must be checked per the applicable design code.
- Applicable codes: AISC 360-22 (US), EN 1993-1-1 (EU), AS 4100 (Australia), CSA S16 (Canada).
Design Procedure
- Establish design criteria: code edition, material grade, design method (LRFD/ASD)
- Determine loads and applicable load combinations
- Analyze structure for internal forces (axial, shear, moment, torsion)
- Check member strength for all applicable limit states
- Verify serviceability criteria (deflection, drift, vibration)
- Detail connections to transfer calculated forces
Worked Example
Problem: Design a structural element for the following conditions:
Span/Height: 15 ft | Load: 50 kips (factored) | Section: W12×65 (A992, Fy=50 ksi) | Code: AISC 360-22 LRFD
Solution:
- Demand: Pu = 50 kips (axial compression)
- Section properties: A = 19.1 in², rx = 5.28 in, ry = 3.02 in
- Slenderness: KL/r = 1.0 × 15 × 12 / 3.02 = 59.6 (controls about weak axis)
- Critical stress: Fcr per AISC Eq E3-2 (intermediate slenderness range)
- Design strength: φcPn = 0.9 × Fcr × Ag — Verify against applied load
- Interaction: Check combined forces per AISC Chapter H if applicable
Result: Section is adequate if φcPn ≥ Pu (50 kips).
Frequently Asked Questions
What design codes does this calculator support?
This calculator supports AISC 360-22 (US LRFD and ASD), EN 1993-1-1 (Eurocode 3), AS 4100 (Australia), and CSA S16 (Canada). Each code edition is verified against the respective design standard. Select your governing code in the calculator interface before entering loads.
How accurate are the results from this calculator?
Results are verified against published design examples and textbook solutions. The calculation engine uses the exact code provisions from the applicable standard. Always verify critical results independently and have designs reviewed by a licensed Professional Engineer. Results are preliminary until independently verified.
Can I save and export my calculations?
Registered users can save calculations to their account for later reference. Currently 10 calculations per hour and 50 per day are available on the free tier. Pro subscription ($19.99/month) increases limits to 500 calculations per month with PDF export capability.
Frequently Asked Questions
What is the most common governing limit state for steel connections? For shear connections, bolt shear or bearing at the bolt holes typically governs. For moment connections, either weld strength at the beam flange or prying action in the end plate governs. Block shear frequently governs in gusset plates and coped beams. Always check all applicable limit states — the weakest link determines the connection capacity.
How does block shear differ from bolt bearing failure? Block shear is a rupture failure along a path combining shear planes (parallel to load) and tension planes (perpendicular to load), causing a block of material to tear out. Bolt bearing is a localized crushing failure around a single bolt hole. Block shear typically governs when bolt groups are close to a free edge; bearing governs for interior bolts with adequate edge distance.
What is the minimum edge distance for bolt holes in structural steel? AISC 360-22 Table J3.4 specifies minimum edge distances by bolt diameter and edge type (sheared or rolled/plasma-cut). For 3/4-inch bolts, minimum edge distance is 1-1/8 inches for sheared edges and 7/8 inches for rolled edges. These are absolute minimums — practical edge distances for full bearing capacity are 2-3 times the bolt diameter.
Is this connection check calculator free? Yes, completely free with unlimited calculations. No registration required.
Related pages
- Steel bolted connection design
- Weld group calculator
- Tension member design
- Bolt bearing reference
- Welded connection reference
Disclaimer (educational use only)
This page is provided for general technical information and educational use only. It does not constitute professional engineering advice. All structural designs must be verified by a licensed Professional Engineer (PE) or Structural Engineer (SE). The site operator disclaims liability for any loss or damage arising from the use of this page.