AISC 360 Bolted Shear Tab Design — Worked Example
This worked example covers a bolted shear tab (single plate shear connection) design per AISC 360-22 Chapter J. Educational use only — always verify with a qualified engineer.
Problem Statement
Beam: W18x35, A992, Fy = 50 ksi, Fu = 65 ksi Reaction (design shear): Vu = 40 kips (LRFD factored) Connection: Shear tab to support column flange Bolts: 3 × 3/4" diameter A325-N bolts in standard holes Bolt spacing: 3" vertical, 1-1/2" edge distance (top and bottom) Shear tab: PL 5/16" × 9" × 0'-9", A36, Fy = 36 ksi, Fu = 58 ksi Weld to support: 1/4" fillet, E70XX
Step 1 — Bolt Shear Capacity (AISC 360 Section J3.6)
For A325-N bolts (threads in shear plane), Fnv = 54 ksi.
Design shear strength per bolt:
phi_rn = phi × Fnv × Ab
= 0.75 × 54 × (pi × 0.75² / 4)
= 0.75 × 54 × 0.4418
= 17.9 kips/bolt
Total bolt shear capacity (3 bolts):
phi_Rn = 3 × 17.9 = 53.7 kips > Vu = 40 kips ✓
Bolt shear: PASS (ratio = 40 / 53.7 = 0.74)
Step 2 — Bearing on Shear Tab (AISC 360 Section J3.10)
Standard hole diameter for 3/4" bolt = 13/16" (AISC Table J3.3).
Bearing strength per bolt on tab (deformation at service load considered):
phi_rn = phi × 2.4 × Fu × d × t
= 0.75 × 2.4 × 58 × 0.75 × 0.3125
= 24.4 kips/bolt
Total: 3 × 24.4 = 73.1 kips > 40 kips ✓
Bearing on tab: PASS
Step 3 — Block Shear on Shear Tab (AISC 360 Section J4.3)
Block shear failure path: shear along the bolt line + tension across the top or bottom edge.
Net shear area:
Anv = t × [Lv - (n - 0.5) × dh]
= 0.3125 × [7.5 - 2.5 × (13/16 + 1/16)]
= 0.3125 × [7.5 - 2.5 × 0.875]
= 0.3125 × 5.31
= 1.66 in²
Net tension area:
Ant = t × [Le - 0.5 × dh]
= 0.3125 × [1.5 - 0.5 × 0.875]
= 0.3125 × 1.063
= 0.332 in²
Block shear strength (tension rupture governs when Ubs × Fu × Ant < 0.6 × Fy × Agv):
phi_Rn = phi × (0.6 × Fu × Anv + Ubs × Fu × Ant)
= 0.75 × (0.6 × 58 × 1.66 + 1.0 × 58 × 0.332)
= 0.75 × (57.8 + 19.3)
= 57.8 kips > 40 kips ✓
Block shear: PASS (ratio = 40 / 57.8 = 0.69)
Step 4 — Shear Yielding of Tab (AISC 360 Section J4.2)
Gross shear area:
Agv = t × d_tab = 0.3125 × 9.0 = 2.81 in²
phi_Rn = phi × 0.6 × Fy × Agv = 1.0 × 0.6 × 36 × 2.81 = 60.7 kips > 40 kips ✓
Shear yielding of tab: PASS
Step 5 — Shear Rupture of Tab (AISC 360 Section J4.2)
Net shear area (3 holes):
Anv = t × [d_tab - n × dh] = 0.3125 × [9.0 - 3 × 0.875] = 0.3125 × 6.375 = 1.992 in²
phi_Rn = phi × 0.6 × Fu × Anv = 0.75 × 0.6 × 58 × 1.992 = 52.2 kips > 40 kips ✓
Shear rupture of tab: PASS
Step 6 — Weld to Support (1/4" Fillet, E70XX)
Weld capacity per inch (AISC 360 Section J2.4):
phi_rn = phi × 0.6 × FEXX × te = 0.75 × 0.6 × 70 × (0.707 × 0.25) = 5.57 kip/in
Weld length = 9" (two sides of tab, single weld each side):
phi_Rn = 5.57 × 9 = 50.1 kips > 40 kips ✓
Weld to support: PASS
Summary
| Check | Demand (kips) | Capacity (kips) | Ratio | Status |
|---|---|---|---|---|
| Bolt shear (3 bolts) | 40.0 | 53.7 | 0.74 | PASS |
| Bearing on tab | 40.0 | 73.1 | 0.55 | PASS |
| Block shear | 40.0 | 57.8 | 0.69 | PASS |
| Shear yielding of tab | 40.0 | 60.7 | 0.66 | PASS |
| Shear rupture of tab | 40.0 | 52.2 | 0.77 | PASS |
| Weld to support | 40.0 | 50.1 | 0.80 | PASS |
Governing check: Bolt shear at ratio 0.74
Common Pitfalls
Ignoring the 1/16-in hole deduction for net area. AISC B4.3 requires adding 1/16 in to the actual hole diameter for net area calculations to account for punching damage. For a 3/4-in bolt in a 13/16-in standard hole, the effective deduction is 13/16 + 1/16 = 7/8 in (0.875 in), not 13/16 in. This error changes the net section and block shear capacity.
Confusing A325-N and A325-X. Threads in the shear plane (N): Fnv = 54 ksi. Threads excluded (X): Fnv = 68 ksi. Using the wrong designation changes bolt shear capacity by 26%. Verify which condition the detail shows — if unclear, use N (conservative).
Not checking tear-out at edge bolts. The edge bolt (closest to the plate end) has less clear distance than interior bolts. Tear-out capacity (1.2 Lc t Fu) can be significantly lower than bearing capacity (2.4 d t Fu). In this example, the bottom bolt tear-out is 20.2 kips vs 24.4 kips bearing — a 17% reduction.
Using the wrong block shear path. The block shear failure path must follow the actual bolt pattern. For a vertical bolt line in a shear tab, the shear path runs along the bolt line and the tension path runs across the top or bottom edge. Drawing the wrong path changes both Anv and Ant.
Forgetting to check shear yielding of the tab. Shear yielding (gross area) and shear rupture (net area) are separate limit states. A thin tab with large holes can fail in rupture before yielding. Both must be checked.
Undersizing the weld to the support. The weld must transfer the full beam reaction plus any moment from eccentricity. A single-sided 1/4-in weld on a 9-in tab gives only 50.1 kips — barely above the 40-kip demand in this example (ratio = 0.80). Increasing the reaction to 50 kips would require a larger weld.
Code Comparison
| Limit State | AISC 360-22 | AS 4100-2020 | EN 1993-1-8 | CSA S16-19 |
|---|---|---|---|---|
| Bolt shear phi | 0.75 | 0.80 | gamma_M2 = 1.25 | 0.80 |
| Bolt shear strength (equivalent to A325-N) | Fnv = 54 ksi (A325-N) | fuf = 830 MPa, phi Vf = phi x 0.62 fuf | fub = 800 MPa, Fv,Rd = 0.6 fub As / gamma_M2 | 0.60 Fu Ab |
| Bearing phi | 0.75 | 0.90 | gamma_M2 = 1.25 | 0.80 |
| Bearing formula | 2.4 d t Fu (deformation at service) | 3.2 d tp fup | 2.5 d t fu / gamma_M2 | 3.0 d t Fu |
| Block shear phi | 0.75 | 0.75 (effective) | Not explicit — uses net section approach | 0.75 |
| Block shear formula | 0.6 Fu Anv + Ubs Fu Ant | 0.6 fy Agv + fu Ant (different basis) | Combined approach per Cl 3.10 | 0.6 Fu An + Ubs Fy Ag |
| Weld phi (fillet) | 0.75 | 0.80 (SP) | gamma_Mw = 1.25 | 0.67 |
| Shear tab convention | AISC Manual Part 10 — standardized tables | Not standard — typically use web side plate (flexible end plate) | Fin plate per SCI P358 | Shear tab per CISC Handbook |
Frequently Asked Questions
What governs the design of a shear tab (single plate) connection? In this example, bolt shear governed at ratio 0.74, but any of the six limit states can govern depending on geometry and loading. For short tabs with large bolts, bolt bearing often controls. For narrow tabs, block shear or shear rupture of the plate typically controls. For large eccentricities, the instantaneous centre of rotation method may reduce effective bolt shear capacity significantly.
Why is the bolt shear capacity 17.9 kips per bolt when the table shows higher values? The 17.9 kips accounts for the eccentricity of the load relative to the bolt group centroid. The shear tab applies load at the beam centreline, offset from the support by the tab length. This eccentricity is resolved through the instantaneous centre method, which reduces the effective shear on the critical bolt. Direct shear without eccentricity would give higher per-bolt capacity.
What is block shear and when does it govern? Block shear is a combined tension-plus-shear failure where a block of material tears out of the connected element. For a shear tab, it involves shear fracture along the bolt line and tension fracture across the top or bottom. AISC 360 Section J4.3: φRn = φ(0.6 × Fu × Anv + Ubs × Fu × Ant). Block shear typically governs for narrow plates with few bolts or when the bolt group is close to a plate edge.
What weld size is typically used to connect a shear tab to a column? For a 3/8" single plate and A992 column flange, a 1/4" E70XX fillet weld on both sides is common in practice (minimum weld size for 3/8" plate per AISC Table J2.4 is 3/16"). The example uses 1/4" weld. The weld must develop the full shear and any moment from eccentricity. Long welds parallel to the load use φRn = 0.75 × 0.6 × FEXX × 0.707 × w per inch of weld.
Can a shear tab be used for beams with significant axial load? Standard shear tabs are designed for shear only. If axial load (from thermal expansion, frame action, or catenary forces) is also present, the connection must be checked for combined shear and axial interaction. This typically requires a more robust connection type (end plate, bolted flange plate) or supplementary stiffeners.
What is the minimum bolt edge distance for a 3/4-inch bolt in a shear tab per AISC? Per AISC Table J3.4, the minimum edge distance for a 3/4-inch bolt in a standard hole is 1 inch for a sheared edge and 1 inch for a rolled or gas-cut edge (the preferred 1-1/4 inch applies to most practical cases). The absolute minimum clear distance for bearing and tear-out is the clear distance from the hole edge to the plate edge, which must satisfy c_l ≥ 1.5d_b = 1.125 in. The AISC Design Manual recommends 1-1/2 in edge distance as standard practice for 3/4-inch bolts.
When does the instantaneous centre of rotation (ICR) method apply to shear tabs? The ICR method applies when the bolt group is loaded eccentrically — meaning the shear force acts at a distance from the bolt group centroid. In a shear tab, the beam reaction is applied at the beam web, which is offset from the support face by the tab length. For the 3-bolt, 9-inch tab in this example with standard 3-inch spacing, the eccentricity is small and direct shear governs. For longer tabs or larger eccentricities (e.g., extended shear tabs), the ICR method reduces the effective capacity of the critical bolt and can govern over the simple shear summation.
Run This Calculation
→ Bolted Connection Calculator — bolt group checks with eccentric shear and block shear per AISC 360, AS 4100, EN 1993, and CSA S16.
→ Gusset Plate Calculator — gusset plate sizing and weld design for bracing connections.
→ Welded Connection Calculator — fillet and groove weld capacity per AISC 360 Chapter J.
Related pages
- Guides and checklists
- Bolted connection checklist
- Bolted connections calculator
- AISC bolt hole sizes — Table J3.3
- Bolt capacity table — A325 & A490
- Bolt spacing and edge distance reference
- Bolt torque chart — ASTM A325 & A490
- Steel Fy & Fu reference — yield and tensile strength by grade
- Steel connection design overview
- How to verify calculator results
- Disclaimer (educational use only)
- AISC 360 design notes
- Bolt hole sizes reference
- Steel connection types
Disclaimer (educational use only)
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