Steel Connection Design Cheatsheet -- Quick Reference with Tables
Steel connection design involves checking multiple limit states across different code provisions, each with its own geometry-dependent formulas and capacity factors. This cheatsheet consolidates the essential numbers into quick-reference tables: bolt shear and tension capacities by diameter and grade, fillet weld capacity per unit length, minimum edge distance and spacing requirements, and a complete limit state checklist. Covering AISC 360-22, AS 4100:2020, EN 1993-1-8, and CSA S16:24.
Use alongside the free connection calculators at SteelCalculator.app.
PRELIMINARY -- NOT FOR CONSTRUCTION. Tabulated values are illustrative and based on standard assumptions (threads in shear plane, standard holes, deformation a design consideration). Always verify with the governing code and applicable National Annex. Connection design must be independently verified by a licensed Professional Engineer.
Copyright Notice
This cheatsheet does not reproduce copyrighted code tables verbatim. Values are computed from published formulas and standard assumptions. Consult the official standard for authoritative requirements.
1. Bolt Shear Capacity Quick Reference
All values assume single shear, threads in shear plane, standard holes. Multiply by 2 for double shear.
Imperial Bolts (A325)
| Bolt Size | A325-N Shear (kips) | A325-X Shear (kips) | A325 Tension (kips) |
|---|---|---|---|
| 1/2" | 9.3 | 11.9 | 19.9 |
| 5/8" | 14.6 | 18.6 | 31.1 |
| 3/4" | 21.0 | 26.8 | 39.8 |
| 7/8" | 28.6 | 36.5 | 54.1 |
| 1" | 37.3 | 47.6 | 70.7 |
| 1-1/8" | 47.2 | 60.3 | -- |
| 1-1/4" | 58.3 | 74.4 | -- |
A325-N: threads in shear plane (phi=0.75). A325-X: threads excluded (higher). A490 (F_u=150 ksi): multiply A325 by 1.25.
Metric Bolts (Grade 8.8, M20)
| Code | Shear Capacity (kN) | Notes |
|---|---|---|
| AS 4100 | 85.9 | phi=0.80, threads in shear |
| EN 1993 | 82.0 | gamma_M2=1.25 (CEN rec.) |
| CSA S16 | 82.3 | phi=0.80, threads in shear |
M20 Grade 8.8 tension capacity: AS 4100 = 97.0 kN, EN 1993 = 92.2 kN (gamma_M2=1.25), CSA S16 = 97.0 kN.
2. Fillet Weld Capacity
All values assume E70XX (70 ksi / 480 MPa) electrode.
| Code | Capacity per mm of Throat | 6 mm Fillet (throat=4.24 mm) |
|---|---|---|
| AISC 360 (LRFD) | 1.392 kips/in per 1/16" leg | 1.46 kN/mm |
| AS 4100 (SP) | 0.816 kN/mm per mm throat | 3.46 kN/mm |
| AS 4100 (GP) | 0.612 kN/mm per mm throat | 2.60 kN/mm |
| EN 1993 (simplified) | 0.91 kN/mm (S355, E42XX)¹ | 3.86 kN/mm |
| EN 1993 (directional) | Up to 22% higher | 4.71 kN/mm |
| CSA S16 | 0.69 kN/mm per mm throat | 2.93 kN/mm |
¹EN 1993 simplified: f_u / (sqrt(3) x beta_w x gamma_M2). S355 (f_u=490), E42 (beta_w=0.90), gamma_M2=1.25.
How to use: For 6 mm fillet weld, throat = 6/sqrt(2) = 4.24 mm. Length = 150 mm. AS 4100 SP: 0.816 x 4.24 x 150 = 519 kN total.
3. Edge Distance and Spacing
Minimum Edge Distances
| Bolt Size | AISC 360 (sheared) | AS 4100 (sheared) | EN 1993 (1.2 x d0) | CSA S16 |
|---|---|---|---|---|
| M16 / 5/8" | 28 mm (1.125") | 24 mm | 22 mm (d0=18mm) | 24 mm |
| M20 / 3/4" | 32 mm (1.25") | 30 mm | 26 mm (d0=22mm) | 30 mm |
| M24 / 1" | 38 mm (1.5") | 36 mm | 32 mm (d0=26mm) | 36 mm |
Bolt Spacing
| Parameter | Minimum | Preferred (Full Bearing) | Maximum |
|---|---|---|---|
| Centre-to-centre | 2.67 d (AISC) / 2.5 d_f (AS) | 3.0 d | min(14t, 7") / 200 mm |
| End distance | 1.5 d_f | 3.0 d (or d0 for EN) | No code max |
Full bearing requires: spacing >= 3d AND end distance >= 3d_0 to achieve alpha_b = 1.0 (EN 1993) or maximum bearing constants in AISC/AS/CSA.
4. Slip-Critical Reference
| Bolt Size | Class A (mu=0.30) | Class B (mu=0.50) |
|---|---|---|
| 3/4" A325 | 8.9 kips (39.5 kN) | 14.8 kips (65.9 kN) |
| 7/8" A325 | 12.2 kips (54.3 kN) | 20.3 kips (90.4 kN) |
| 1" A325 | 15.9 kips (70.8 kN) | 26.5 kips (118 kN) |
| M20 8.8 (AS 4100) | 34.0 kN | 56.7 kN |
AISC 360: slip resistance = mu x D_u x h_f x T_b x n_s. Pretension: 3/4" A325 = 28 kips. Class A: clean mill scale. Class B: blast-cleaned.
5. Block Shear Quick Check
Block shear combines shear on planes parallel to load and tension on perpendicular plane:
Across Codes
| Code | Formula | phi/gamma |
|---|---|---|
| AISC 360 | 0.60F_uA_nv + U_bsF_uA_nt <= 0.60F_yA_gv + U_bsF_uA_nt | 0.75 |
| AS 4100 | 0.60f_upA_nv + f_upA_nt | 0.75 |
| CSA S16 | phi_u x (U_tA_nF_u + 0.60A_gv(F_y+F_u)/2) | 0.75 |
| EN 1993 | f_uA_nt/gamma_M2 + (1/sqrt(3))f_yA_nv/gamma_M0 | 1.25/1.00 |
6. Complete Limit State Checklist
| # | Limit State | Applies When |
|---|---|---|
| 1 | Bolt shear | Always (shear connections) |
| 2 | Bolt tension | Axial tension, prying, hangers |
| 3 | Bolt combined shear + tension | Any connection with both V and N |
| 4 | Bolt bearing (edge) | Bolts near plate edge |
| 5 | Bolt bearing (interior) | Bolts with sufficient spacing |
| 6 | Block shear rupture | Coped beams, gussets, angles |
| 7 | Net section tension | Tension members with bolt holes |
| 8 | Gross section yielding | Away from bolt holes |
| 9 | Weld strength (fillet/groove) | Any welded element |
| 10 | Slip resistance | Slip-critical connections |
| 11 | Prying action | Tension bolts through flexible flange |
| 12 | Weld metal / base metal | Any welded connection |
| 13 | Plate tear-out | Short edge distance (e < 2d) |
| 14 | Panel zone shear | Moment frame beam-column joints |
Code Section References
| # | AISC 360-22 | AS 4100 | EN 1993-1-8 | CSA S16 |
|---|---|---|---|---|
| 1 | J3.6 | 9.3.2 | Table 3.4 | 13.12 |
| 2 | J3.6 | 9.3.3 | Table 3.4 | 13.12 |
| 3 | J3.7 | 9.3.6 | Table 3.4 | 13.12 |
| 4 | J3.10 | 9.3.4.3 | Table 3.4 | 13.12 |
| 5 | J3.10 | 9.3.4.4 | Table 3.4 | 13.12 |
| 6 | J4.3 | 9.1.9 | 3.10.2 | 13.11 |
| 7 | J4.1 | 9.1.8 | 6.2.3 | 13.2 |
| 8 | J4.1 | 9.1.7 | 6.2.3 | 13.2 |
| 9 | J2.4 | 9.7.3 | 4.5.3 | 13.13 |
| 10 | J3.8 | 9.3.5 | 3.9 | 13.12.2 |
7. Typical Assumptions
All tabulated values assume:
- Threads in shear plane unless marked "X" (excluded)
- Standard holes (d_0 = d + 1/16" or d + 2 mm metric)
- Deformation is a design consideration
- A36 plate (AS 4100 Gr 250, EN 1993 S235) for bearing checks
- A325 or Grade 8.8 bolts unless A490/Grade 10.9 shown
- E70XX electrodes for weld tables
- Single shear unless marked "double shear"
Adjust when: plate grade differs, hole size differs, threads excluded, or double shear.
Frequently Asked Questions
What are standard bolt capacities for A325 and Grade 8.8 bolts?
A325 3/4": shear = 21.0 kips (N-type), 26.8 kips (X-type), tension = 39.8 kips. M20 Grade 8.8: 82-86 kN shear (varies by code). The variation comes from differing phi/gamma_M2 factors and thread-in-plane assumptions.
What are minimum edge distances?
AISC: 1-1/4" (3/4" bolt, sheared). EN 1993: 1.2 x d_0. AS 4100: 1.5 d_f (sheared). Safe default: 1.5 x bolt diameter. Full bearing requires 3 x d_0.
What is the weld capacity per mm for E70XX fillet weld?
AISC LRFD: 1.392 kips/in per 1/16" leg. AS 4100 SP: 0.816 kN/mm per mm throat. EN 1993 simplified: ~0.91 kN/mm per mm throat (S355, E42). CSA S16: 0.69 kN/mm per mm throat. A 6 mm fillet weld: ~3.46 kN/mm (AS 4100 SP).
What limit states must be checked for bolted connections?
Essential: bolt shear, bolt bearing (edge + interior), block shear, net section tension, gross section yielding. For tension: add bolt tension and combined shear+tension. For moment: add prying and weld checks. For slip-critical: add slip resistance. Complete 14-item checklist in Section 6.
Is this calculator a replacement for professional engineering judgment?
No -- quick reference for educational use only. All designs must be independently verified by a licensed Professional Engineer. Results are PRELIMINARY -- NOT FOR CONSTRUCTION.
Run This Calculation
- Bolted Connections Calculator -- Any of four codes for bolt shear, bearing, tension, block shear, slip-critical
- Welded Connections Calculator -- Fillet and groove weld capacity with directional method
- Base Plate & Anchors Calculator -- Column base plates with anchor bolt checks
- Beam Capacity Calculator -- Beam-to-connection interface moment and shear values
Related Pages
- Steel Connection Design Guide -- Types, Checks & Worked Examples
- EN 1993-1-8 Steel Connection Design -- Bolt & Weld Checks
- Fillet Weld Size Selection Guide
- Block Shear Design Guide -- Four Codes
- Bolt Capacity Guide -- AISC, EN 1993, AS 4100
- Bearing vs Slip-Critical Bolts
- Disclaimer (educational use only)