13 Steel Connection Types Compared — Bolted Shear to Moment End Plate

A comprehensive reference for the 13 most common steel connection types used in building construction. Covers shear connections, moment connections, splices, base plates, and bracing connections. Includes design considerations, governing limit states, and links to the Designer Hub connection design tools.

Connection Classification — Shear vs Moment

Steel connections are classified by the forces they transfer and the restraint they provide:

Shear (simple) connections transfer vertical shear force but negligible bending moment. The beam end is free to rotate, so the connection is modelled as a pin in the structural analysis. Shear connections are simpler to fabricate and erect than moment connections and are preferred where possible.

Moment (rigid or semi-rigid) connections transfer both shear and bending moment and provide rotational restraint. The actual degree of fixity depends on the connection stiffness relative to the connected member stiffness. Full moment connections (greater than approximately 90 percent fixity) are modelled as fixed in the analysis. Semi-rigid connections (20 to 90 percent fixity) require explicit modelling of the connection rotational stiffness.

The Designer Hub S6 connection design stage supports both shear and moment connection types, with the connection category (shear or moment) derived from the S0 geometry input (pinned or fixed base, simple or moment-resisting beam-column connections).

Shear Connection Types (1-6)

1. Shear Tab (Single Plate)

A single vertical plate is shop-welded to the supporting member (column or girder web) and field-bolted to the beam web. Also called a single-plate shear connection or fin plate (UK terminology).

How it works. The beam end reaction is transferred through the bolts in single shear into the plate, then through the weld into the support. The connection allows rotation through plate flexure and bolt slip.

Design checks: bolt shear (single shear), bolt bearing on the plate and beam web, plate shear yielding, plate shear rupture, weld capacity (fillet weld between plate and support), block shear of the plate and beam web.

Typical use. Beam-to-column or beam-to-girder connections where the beam frames into the support at 90 degrees. Standard for floor and roof beam connections in braced frames. Plate thickness typically 6 to 12 mm, 2 to 5 bolts per connection.

Advantages. Simple fabrication (one plate, fillet welds), fast erection (one side only), low cost. Limitations: limited to shear-only transfer, single-shear bolts have lower capacity than double-shear.

2. Double Angle (Web Angles)

Two angles are bolted or welded to the beam web (shop) and bolted or welded to the supporting member (field). Also called clip angle or web cleat connections.

How it works. The outstanding legs of the angles are field-bolted to the support. The beam end reaction is transferred through the bolts in double shear (where angles are on both sides of the web). Rotation is accommodated through angle leg flexure.

Design checks: bolt shear (double shear if both legs are bolted), bolt bearing, angle leg flexure, angle shear yielding, block shear, weld capacity.

Typical use. Beam-to-column web or beam-to-girder connections. Common in industrial buildings and older construction. Still widely used where the beam depth does not permit a shear tab.

Advantages. Accommodates some beam end rotation through angle leg flexibility, double-shear bolts provide approximately twice the capacity of single-shear bolts for the same bolt diameter. Limitations: requires two angles (more pieces than a shear tab), shop bolting or welding to the beam adds a fabrication step.

3. Seated Connection (Unstiffened and Stiffened)

The beam bears on a seat angle or seat plate attached to the support. A top angle or clip provides lateral restraint but does not carry vertical load. Seated connections are either unstiffened (for light reactions) or stiffened (with stiffener plates under the seat for heavier reactions).

How it works. The beam end reaction is transferred by bearing on the seat angle horizontal leg. The vertical leg of the seat angle transfers the reaction to the support through bolts or welds. The top angle prevents the beam from twisting and provides nominal lateral restraint.

Design checks: seat angle bending (horizontal leg), seat angle shear (vertical leg), bolt shear and bearing, weld capacity, beam web local yielding and web crippling at the bearing point, stiffener design (if stiffened seat).

Typical use. Erection seat for beam placement before final bolting. Also used where the beam end reaction is too high for a shear tab (a stiffened seat can carry reactions of 500 kN or more).

Advantages. Provides a positive bearing seat during erection, high capacity for stiffened seats. Limitations: more complex fabrication (seat angle fitting, stiffeners), may interfere with floor slab details, top angle required for lateral restraint.

4. End Plate Shear Connection (Flush or Partial Depth)

A vertical plate is shop-welded to the beam end and field-bolted to the supporting member. Unlike a moment end plate, the plate is flush with or slightly shorter than the beam depth, and the bolt layout is not designed to transfer moment.

How it works. The beam end reaction is transferred through the end plate in shear and bearing to the support bolts. The end plate is welded to the beam web (and sometimes flanges, but the flange welds are not designed for moment transfer). Bolt rows are near the top and bottom of the plate for erection stability but not proportioned for moment.

Design checks: bolt shear (single shear), bolt bearing on end plate, end plate shear yielding, weld between beam and end plate (fillet weld to web), block shear of end plate.

Typical use. Alternative to shear tab where the beam frames into a column flange or where field bolting from one side is preferred. Common in the UK (flexible end plate) per SCI P358.

Advantages. All welding is shop-done, field connection is bolting only, no beam copes required. Limitations: not a moment connection, end plate fabrication adds cost compared to a shear tab.

5. Single Angle Connection

A single angle is bolted or welded to the beam web (shop) and bolted or welded to the support (field). Economical for light to moderate reactions.

How it works. Similar to the double angle, but with one angle on one side of the web. The reaction is transferred through single-shear bolts into the outstanding leg.

Design checks: bolt shear (single shear), bolt bearing, angle leg bending, block shear, weld capacity.

Typical use. Light beam connections (reactions up to approximately 100 kN), infill beams, mezzanine floor beams.

Advantages. Minimum material (one angle), simple fabrication. Limitations: lower capacity than double angle, eccentricity of load path must be considered when the connection is on one side only.

6. Knife Plate (Through Plate)

A plate passes through a slot in the supporting hollow section (HSS or CHS column) and is welded on both sides. The beam web is field-bolted to the protruding plate. This is the standard shear connection for HSS columns where a shear tab on the column face would cause local wall bending.

How it works. The plate passes through the column section, transferring the beam reaction to both column walls in bearing plus weld shear. This eliminates the HSS wall punching shear and wall bending limit states that govern face-mounted connections.

Design checks: bolt shear, bolt bearing on plate, plate shear and tension yielding, weld between plate and column walls, HSS wall local yielding at the slot edges, column net section at the slot.

Typical use. Beam-to-HSS-column connections in braced frames, truss connections to HSS chords.

Advantages. High capacity, avoids HSS wall local failure modes, symmetric load transfer. Limitations: requires slotting the HSS (fabrication complexity), plate must be sized for column interior access.

Moment Connection Types (7-10)

7. Flush End Plate Moment Connection

A vertical end plate is shop-welded to the beam end and field-bolted to the column flange. The plate is the full depth of the beam (flush with both flanges). Bolt rows are provided in the tension zone (near the top flange) and the compression zone (near the bottom flange).

How it works. The applied moment is resolved into a tension-compression couple: the tension flange bolts carry the tension component, and the compression flange bolts or bearing transfer the compression. The end plate bending and bolt tension govern the connection capacity.

Design checks: bolt tension (including prying), bolt shear, bolt combined tension + shear interaction, end plate bending (yield line analysis), beam flange to end plate weld (full-penetration or fillet), beam web to end plate weld (fillet), column flange bending, column web panel zone shear, column web local yielding, column web crippling, column flange local bending.

Typical use. Beam-to-column moment connections in portal frames and moment-resisting frames. For light to moderate moments. For higher moments, an extended end plate (see type 8) is used.

Advantages. All welding shop-done, field bolting only, simpler than welded moment connections. Limitations: bolt rows must fit within the beam depth, limiting the lever arm and moment capacity. Prying amplification can be significant.

8. Extended End Plate Moment Connection

Similar to the flush end plate, but the end plate extends beyond the tension flange (and optionally the compression flange) to provide additional bolt rows outside the beam depth, increasing the lever arm and moment capacity.

How it works. The extended portion above the top flange carries one or two additional bolt rows, increasing the tension couple lever arm by 100 to 200 mm compared to a flush end plate. The compression side may also be extended to provide symmetry and simplify fabrication.

Design checks: Same as flush end plate plus: end plate bending for the extended portion (cantilever or T-stub behaviour), bolt rows in the extension, stiffener plates between the extended end plate and the beam flange (if required to control plate bending).

Typical use. Portal frame eaves connections, moment-resisting frame beam-column connections, anywhere a high moment capacity is required. The most common moment connection for multi-storey steel frames.

Advantages. Higher moment capacity than flush end plate (15-30 percent increase from the extended bolt rows), all shop welding, field bolting only. Limitations: end plate extends beyond beam depth (may interfere with floor slab or ceiling services), more bolts, thicker end plate, higher fabrication cost.

9. Welded Flange Moment Connection

The beam flanges are field-welded to the column flange using full-penetration groove welds. The beam web is field-bolted to a shear tab welded to the column. This is the classic "welded moment connection" used in high-seismic applications.

How it works. The beam flange welds transfer the flange forces (tension and compression) directly into the column. The web shear tab transfers the shear. The connection is modelled as fully rigid when the flange welds develop the full flange capacity.

Design checks: flange weld capacity (full-penetration, matched to flange strength), shear tab bolt shear and bearing, shear tab weld, column flange bending, column web panel zone shear, column web local yielding and crippling, beam web to shear tab block shear.

Typical use. Special moment frames (SMF) in high-seismic regions, connections requiring field welding for architectural or access reasons, base plate moment connections.

Advantages. Full moment capacity (can develop Mp of the beam), compact (no protruding end plate), preferred for seismic applications per AISC 341. Limitations: field welding requires inspection (ultrasonic testing), weather protection during welding, higher erection cost than bolted connections.

10. Bolted Flange Plate Moment Connection

The beam flanges are connected to the column flange using flange cover plates and bolts (or splice plates). The beam web is bolted to a shear tab. This is a fully bolted moment connection — no field welding required.

How it works. Top and bottom flange plates transfer the flange forces through bolts in shear and bearing. The web shear tab transfers the vertical reaction. The connection provides moment transfer without field welding.

Design checks: bolt shear (single or double shear) in flange plates, bolt bearing on flange plates and beam/column flanges, flange plate tension yielding and rupture, net section at bolt holes, shear tab design (as for a shear connection), block shear of flange plates.

Typical use. Where field welding is prohibited or impractical (remote sites, extreme weather), or where the connection must be demountable.

Advantages. No field welding, all-bolted erection, demountable. Limitations: flange plates protrude beyond the beam flanges (aesthetic and clearance issues), more bolts than a welded connection, slip-critical bolts may be required for load reversal.

Special Connection Types (11-13)

11. Beam Splice

A beam splice connects two beam segments end-to-end, either at a point of contraflexure (zero moment) or at a location selected for transport and erection convenience. Splices for long-span beams (longer than trucking length, typically 12 to 18 metres) are required for delivery.

How it works. The splice transfers axial force, shear, and moment (depending on location) from one beam segment to the next. Flange splice plates transfer flange forces. Web splice plates transfer shear and the web portion of the moment. If the splice is at a point of contraflexure, moment transfer is minimal and the design is simplified.

Design checks: flange plate tension/compression capacity, web plate shear capacity, bolt shear and bearing on all plates, net section at bolt holes, block shear, flexural capacity of the spliced section (must restore the beam moment capacity unless located at a point of zero moment).

Typical use. Long-span beams and girders, bridge girders, crane runway girder splices, any beam exceeding trucking length.

Advantages. Enables construction of beams longer than transport limits. Limitations: complex fabrication (multiple plates, many bolts), more expensive than a continuous beam if transport permits.

12. Column Base Plate (Pinned and Fixed)

The column base plate transfers the column axial force, shear, and moment (if fixed) to the concrete foundation. The connection between the steel column and the concrete footing is through anchor bolts.

Pinned base plate. Thin plate with 2 or 4 anchor bolts, designed for axial compression and shear only. No moment transfer. The plate is sized for the bearing stress on the concrete (ACI 318, EN 1992, or AS 3600).

Fixed base plate. Thick plate with 4 to 8 anchor bolts, stiffeners, and designed for combined axial, shear, and moment. The anchor bolts in the tension side of the base plate resist the uplift component of the moment couple. The compression side bears on the concrete through the base plate.

Design checks (fixed base): concrete bearing stress (axial + moment), base plate thickness (bending from concrete bearing pressure), anchor bolt tension capacity (including concrete breakout and pullout per ACI 318), anchor bolt shear capacity (including concrete pryout), base plate stiffener design (compression and weld), weld between column and base plate, shear key design if required.

Typical use. Every steel column requires a base plate connection to the foundation.

Advantages. Standardised design procedures (AISC Design Guide 1, SCI P398), well-understood behaviour. Limitations: anchor bolt placement tolerances are critical (template required), fixed base plates are materially expensive (thick plate, many bolts and stiffeners), foundation size increases for overturning resistance.

The Designer Hub S6 base plate design page checks both pinned and fixed base plates for all four design standards.

13. Bracing Connection (Gusset Plate)

Bracing connections transfer axial force from a diagonal brace (angle, channel, HSS, or W-shape) to the beam-column joint through a gusset plate. The gusset plate is welded to the beam and column and bolted to the brace.

How it works. The brace axial force is resolved into horizontal and vertical components at the beam-column joint. The gusset plate transfers these forces through welds to the beam and column. The Whitmore section (effective width of gusset plate for tension and compression) is checked. The gusset-to-brace connection may be bolted (for erection) or welded (shop-assembled).

Design checks: gusset plate tension yielding and rupture (Whitmore section), gusset plate compression buckling, gusset plate block shear, bolt shear and bearing (brace-to-gusset), weld between gusset and beam/gusset and column, beam and column local checks (web yielding, crippling, flange bending) at the gusset attachment, interface forces transferred to the beam-column joint.

Typical use. Concentrically braced frames (CBF), eccentrically braced frames (EBF), buckling-restrained braced frames (BRBF), vertical bracing in industrial buildings for longitudinal stability, roof and wall bracing in portal frame buildings.

Advantages. Simple fabrication (flat plate), all-bolted brace-to-gusset connection possible, standardised design per AISC 360 Section J4 and AISC Design Guide 29. Limitations: gusset plate may interfere with cladding or services, bracing layout must be coordinated with architectural openings.

Connection Design Workflow in the Designer Hub

The Designer Hub S6 connection design stage follows this sequence for each connection:

  1. Extract forces from S4 FEA results for the governing load combination. This provides the axial force, shear force, and bending moment at each member end.

  2. Classify the connection type based on the S0 geometry and S1 section assignments. The pipeline determines whether each beam-column junction requires a shear or moment connection, and whether splices or base plates are needed.

  3. Select the connection configuration. For bolted connections, the pipeline suggests bolt diameter, grade, and spacing based on the member sizes and force demands. For welded connections, the pipeline suggests weld type, size, and extent.

  4. Check all applicable limit states per the governing design standard. For each connection, 8 to 15 individual limit states are checked, depending on the connection type.

  5. Report the governing limit state and DCR. If any check exceeds 1.0, the pipeline suggests modifications: increase bolt diameter, increase end plate thickness, add stiffeners, or change the connection type.

The Designer Hub S6 page displays a schematic of each connection with the bolt layout, weld sizes, and utilisation ratios.

Frequently Asked Questions

What is the difference between a shear connection and a moment connection?

A shear connection transfers only vertical shear and allows rotation (pinned behaviour). A moment connection transfers shear plus bending moment and restrains rotation (fixed or semi-rigid behaviour). Shear connections use angles, shear tabs, or fin plates. Moment connections use end plates, flange plates, or welded flanges. The connection type determines whether the frame is analysed as simply supported or continuous, which affects member sizes, drift, and foundation design.

How are bolted end plate connections designed for moment?

The tension flange bolts are treated as an equivalent T-stub per AISC 360 Part 9 or EN 1993-1-8 Clause 6.2.4. Bolt row forces are proportional to their distance from the compression flange. The end plate thickness is sized for the bending demand from the bolt forces, including prying action. Extended end plates provide additional bolt rows above the top flange, increasing the lever arm and moment capacity by 15 to 30 percent compared to flush end plates.

What is prying action and how is it accounted for?

Prying action occurs when a connecting element (end plate or angle leg) deforms under bolt tension, creating additional tension in the bolt beyond the directly applied load. The prying force can add 20 to 50 percent to the bolt tension demand. Prying is controlled by increasing the fitting thickness or using smaller bolt gauge distances. AISC 360 Manual Part 9 and EN 1993-1-8 provide calculation methods.

When should slip-critical bolts be used instead of bearing bolts?

Slip-critical bolts are required when: (1) the connection is subject to fatigue or load reversal, (2) oversized or slotted holes are used with loads parallel to the slot, (3) minimal deformation under service loads is needed (crane girders, machinery supports), or (4) the code mandates SC bolts for specific seismic connections. In all other cases, bearing-type (snug-tight) bolts are permitted and cost less.

Related Resources

Disclaimer: This content is for educational purposes only. Results must be verified by a licensed professional engineer. Steel Calculator provides preliminary design tools — NOT a substitute for professional engineering judgment.