Simple Shear Connection Design — AISC Tables
Simple shear connections are the most frequently designed connection in structural steel. They transfer vertical shear from beams to columns while allowing end rotation. AISC Manual Tables 10-1 through 10-12 provide precalculated capacities for standard configurations. This page covers the design procedure for each type.
Principles of Simple Shear Connections
A simple connection is designed to transfer shear only. It must:
- Support the gravity reaction with adequate safety margin
- Allow beam end rotation without developing significant moment
- Accommodate fabrication tolerances (beam length ±1/8 in typical)
- Be economical (these are the most numerous connections in a building)
How Much Rotation?
| Span (ft) | Typical Rotation (rad) | Degrees |
|---|---|---|
| 20 | 0.005 | 0.3° |
| 30 | 0.008 | 0.5° |
| 40 | 0.011 | 0.6° |
| 50 | 0.014 | 0.8° |
The connection flexibility must accommodate this rotation without developing significant moment. AISC requires connections to have sufficient rotational ductility.
Single-Plate (Shear Tab) Connections
The single-plate connection is the simplest and most economical shear connection. A single plate is shop-welded to the supporting member and field-bolted to the beam web.
Configuration
| Parameter | Typical Value |
|---|---|
| Plate width | Beam depth - 2 in (min) |
| Plate thickness | 3/16 to 1/2 in |
| Bolt diameter | 3/4 or 7/8 in |
| Number of bolts | 2 to 12 (vertical line) |
| Bolt type | A325-N (standard holes) |
| Weld to support | Fillet, both sides |
| Edge distance | 1.5 in (typical) |
Design Procedure
- Determine factored reaction Ru (LRFD)
- Select number of bolts from AISC Table 10-10 (for given plate thickness and bolt diameter)
- Check bolt shear: φRn per bolt from AISC Table 7-1
- Check bolt bearing on plate: φRn per AISC Table 7-5 to 7-7
- Check bolt bearing on beam web: Must be adequate for bolt forces
- Check plate shear yielding: φRn = 0.9 × 0.6 × Fy × Agv
- Check plate shear rupture: φRn = 0.75 × 0.6 × Fu × Anv
- Check block shear: AISC Section J4.3
- Check plate flexure: Moment from eccentricity = Ru × e, where e is bolt group eccentricity
- Check weld capacity: φRn = 0.75 × 0.6 × FEXX × 0.707 × a × Lw
AISC Table 10-10 Example
For a single-plate connection with 3/4 in A325-N bolts, PL 5/16 in thick:
| Bolts | φRn (kips) | Beam Web Min (in) |
|---|---|---|
| 2 | 38.3 | 0.285 |
| 3 | 57.5 | 0.285 |
| 4 | 76.6 | 0.285 |
| 5 | 95.8 | 0.285 |
| 6 | 115.0 | 0.285 |
| 7 | 134.1 | 0.285 |
| 8 | 153.3 | 0.285 |
| 9 | 172.4 | 0.285 |
| 10 | 191.6 | 0.285 |
Capacities assume single shear, standard holes, and 3 in bolt spacing.
Extended Single Plate
When the connection must clear the column flange or accommodate beam depth variations, the plate extends beyond the column flange:
- Extended tab plate thickness: Typically 1/2 to 3/4 in
- Must check plate bending and weld capacity for the extended portion
- AISC Table 10-11 covers extended configurations
Double-Angle Connections
Two angles are bolted to the beam web and bolted or welded to the supporting member. Double-angle connections are very common because they accommodate more rotation than single plates.
Configuration
| Parameter | Typical Value |
|---|---|
| Angle size | L3×3 to L4×4 |
| Angle thickness | 5/16 to 5/8 in |
| Bolt diameter | 3/4 or 7/8 in |
| Legs to beam | Bolted (standard) |
| Legs to support | Bolted or welded |
Design — AISC Tables 10-1 through 10-4
| Table | Configuration |
|---|---|
| 10-1 | Bolted-bolted, standard holes |
| 10-2 | Bolted-bolted, short slots |
| 10-3 | Bolted-welded |
| 10-4 | Bolted-bolted, SSL and SSO |
Limit States for Double Angles
- Bolt shear (beam side and support side)
- Bolt bearing on angles
- Bolt bearing on beam web
- Angle shear yielding (gross section)
- Angle shear rupture (net section)
- Block shear (angles and beam web)
- Angle leg local bending (prying action)
- Weld shear (if welded to support)
- Beam web tear-out
Double-Angle Eccentricity
The eccentricity depends on whether the connection is bolted-bolted or bolted-welded:
| Configuration | Eccentricity (e) |
|---|---|
| Bolted-bolted | Center of bolt group to support face |
| Bolted-welded | Face of outstanding leg |
The eccentricity creates additional shear and moment in the connection.
End Plate Connections
A plate is shop-welded to the beam end and field-bolted to the support. Clean appearance with no visible connection hardware on the beam side.
Configuration
| Parameter | Typical Value |
|---|---|
| Plate thickness | 1/4 to 1/2 in |
| Plate width | Beam depth minus 1 in |
| Bolt diameter | 3/4 or 7/8 in |
| Number of bolts | 2 to 8 (single or double column) |
AISC Tables 10-5 and 10-6
Table 10-5: Bolted end-plate connections (shear only) Table 10-6: Bolted end-plate connections (with axial)
Limit states include bolt shear, bearing, plate shear, block shear, and weld capacity. The plate must be thick enough to prevent prying action from shear eccentricity.
Seated Connections
An angle seat supports the beam from below. The beam sits on the seat angle, and a top angle provides stability.
Types
| Type | Description | Capacity Range |
|---|---|---|
| Unstiffened seat | Single angle seat | 5-50 kips |
| Stiffened seat | Angle seat with stiffener | 20-150 kips |
Design — AISC Tables 10-7 and 10-8
The seat angle must resist:
- Bearing on the beam flange
- Bending of the outstanding leg
- Weld shear to the support
- Top angle capacity (stability only, not structural)
Connection Selection Guide
| Situation | Recommended Connection | AISC Table |
|---|---|---|
| Beam to column web | Single-plate shear tab | 10-10, 10-11 |
| Beam to column flange (light) | Single-plate shear tab | 10-10 |
| Beam to column flange (heavy) | Double-angle | 10-1 to 10-4 |
| Beam to girder web | Double-angle | 10-1 |
| Truncated beam (short) | End plate | 10-5, 10-6 |
| Beam on top of column | Seated connection | 10-7, 10-8 |
| Deep beam (W30+) | Double-angle (bolted) | 10-1 |
| Light beam (W8-W12) | Single-angle | 10-12 |
| Architectural (hidden conn.) | End plate | 10-5 |
Worked Example — Single-Plate Connection
Given: W18×50 beam to W14×68 column. Factored reaction Ru = 65 kips (LRFD). Use 3/4 in A325-N bolts, PL 5/16 in A36.
Step 1: Select bolts from Table 10-10 5 bolts at 3 in spacing: φRn = 95.8 kips > 65 kips → OK
Step 2: Check beam web W18×50 web thickness = 0.355 in > 0.285 in minimum → OK
Step 3: Plate shear yielding Agv = 0.3125 × (5 - 1) × 3 = 3.75 in² (not exact, but for check) φRn = 0.9 × 0.6 × 36 × 5 × 0.3125 = 30.4 kips (each segment) — governed by bolt group
Step 4: Weld to column Use 5/16 in fillet weld, both sides: φRn = 0.75 × 0.6 × 70 × 0.707 × 0.3125 × 2 × 12 = 133.2 kips > 65 → OK
Result: 5-bolt single-plate shear tab, PL 5/16, with 5/16 in fillet weld.
Frequently Asked Questions
What is the most economical shear connection? The single-plate shear tab is the most economical because it uses one plate, one weld, and one line of bolts. It requires the least fabrication and erection time. AISC Manual Table 10-10 makes selection straightforward.
When should I use a double-angle instead of a single-plate? Use double angles when: (1) the connection requires more rotational flexibility, (2) the beam-to-column alignment needs tolerance in both directions, (3) the reaction exceeds single-plate practical limits, or (4) the supporting member is a beam web where a single plate cannot be welded easily.
What is block shear failure? Block shear is a combined failure mode where a block of material tears out from the plate or beam web. It involves shear yielding or rupture along one direction and tension rupture along the perpendicular direction. Check per AISC Section J4.3. It often governs for connections with few bolts in thin material.
Can a shear connection resist axial force? Standard shear connections have some axial capacity, but it is limited. If significant axial force exists (e.g., from wind uplift or brace forces), use the axial+shear interaction tables (AISC Table 10-6 for end plates) or design the connection for combined loading per AISC Chapter J.
Related Pages
- Bolted Connections — Bolt capacity calculator
- Welded Connections — Weld capacity calculator
- Connection Types Explained — All connection types
- Moment Connection Design — Moment connections
- Seismic Connections — AISC 341 requirements
Disclaimer
This is a calculation tool, not a substitute for professional engineering certification. All results must be independently verified by a licensed Professional Engineer (PE) or Structural Engineer (SE) before use in construction, fabrication, or permit documents. The user is responsible for the accuracy of all inputs and the verification of all outputs.