----------------- | :----------------------- | :---------------: | :-------------: | | Simply supported | L/4 from support | 24% of midspan Mf | 50% of end Vf | | Continuous (end span) | ~0.20L from support | ~15% of Mf_pos | ~60% of end Vf | | Continuous (int span) | Inflection point (0.21L) | Near zero | Moderate | | Cantilever | Back-span connection | Full support Mf | Full support Vf |

For transportation constraints, practical beam lengths are typically 12 m to 18 m maximum. Splices are required for longer spans or when site access limits piece size.

Bolted Beam Splice Design

Flange Splice Plates

Per CSA S16 Clause 13.10, flange splice plates develop the flange force through bolts in shear and bearing. The flange force at the splice:

Pf = Mf / (d - tf)

Where Mf = factored moment at splice, d = beam depth, tf = flange thickness.

For a W610×155 beam with Mf = 800 kN·m: d = 611 mm, tf = 19.3 mm Pf = 800 × 10^6 / (611 - 19.3) = 1,352 kN per flange

Flange Plate Sizing

Web Splice Plates

The web splice transfers shear force and a portion of the moment resisted by the web. Web splice plates (two sides) are designed for:

Vf_web = Vf_total (shear at splice) Mw = (tw × hw^3 / 12) / Ix × Mf (web portion of moment)

For a W610×155: Ix_web = 11.6 × (611 - 2×19.3)^3 / 12 = 11.6 × 572.4^3 / 12 = 181 × 10^6 mm^4 Ix_total = 1,290 × 10^6 mm^4 Moment fraction to web = 181 / 1,290 = 14%

Web Plate Bolts

Slip-Critical vs Bearing-Type

For beam splices subject to fatigue or reversal, slip-critical (SC) bolts per CSA S16 Clause 13.12.3 are required:

• SC Class A (clean mill scale): slip coefficient μ = 0.30
• SC Class B (blast-cleaned): slip coefficient μ = 0.50

Slip resistance: V_sr = 0.53 × 0.70 × μ × n_b × A_b × F_u (single shear, one bolt, one shear plane)

For M20 A325M SC-B: V_sr = 0.53 × 0.70 × 0.50 × 1 × 314 × 825 / 1000 = 48.0 kN per bolt per shear plane.

CJP Welded Beam Splice

Complete-joint-penetration groove welds provide full-strength moment splices. Per CSA S16 Clause 14, CJP welds matching the base metal strength develop the full capacity of the connected sections without requiring strength calculations for the weld itself.

CJP Splice Preparation

Welding consumable: E4918 (E7018) low-hydrogen electrodes for 350W and 350WT steels. Preheat for thickness > 38 mm: 65°C minimum per CSA W59.

Weld Access Hole Requirements

Per CSA S16 Clause 14.5, weld access holes (rat holes) are required at beam flange-to-web CJP splices to ensure continuity of the web weld past the flange. Minimum dimensions:

• Length: 1.5 × flange thickness (typical 30-50 mm)
• Height: 25 mm clear from flange
• Radius at web end: 10 mm minimum

Worked Example — W610×155 Beam Splice

Given: W610×155 beam, 350W steel. Splice at L/4 of a 12 m simply supported span. Factored moment Mf = 800 kN·m, factored shear Vf = 350 kN. Bolted splice with flange plates and web plates. M22 A325M bolts, SC Class B.

Step 1 — Flange Force: d = 611 mm, tf = 19.3 mm Pf = 800 × 10^6 / (611 - 19.3) = 1,352 kN per flange

Step 2 — Flange Plate Design: Try 230 mm wide × 22 mm thick plate (Grade 350W). Ag = 230 × 22 = 5,060 mm^2 Tr_plate = 0.90 × 5,060 × 350 / 1000 = 1,594 kN > 1,352 kN. OK.

Step 3 — Flange Bolts (SC-B, single shear per bolt pair): V_sr per bolt = 48.0 kN (M20) or 58.1 kN (M22) Number of bolts: n = Pf / (V_sr × 1 bolt/row × 2 shear planes) = 1,352 / (58.1 × 2) = 11.6 → 12 M22 bolts (6 per side, 2 rows of 3). Use 8 M22 bolts per side (2 rows of 4). OK.

Step 4 — Web Splice: Web portion moment: Mw = Mf × (Iw/Ix) = 800 × 0.14 = 112 kN·m Web force couple: Pw = Mw / (hw - edge_dist) = 112 × 10^6 / (572 - 70) = 223 kN Total vertical on web bolts: V_shear = 350 kN Resultant per bolt = sqrt((223/4)^2 + (350/4)^2) = sqrt(55.8^2 + 87.5^2) = 103.7 kN V_sr_bearing per M20 bolt in 11.6 mm web (t = 11.6 mm): Br = 3 × 0.80 × 20 × 11.6 × 450 / 1000 = 250 kN >> 103.7 kN. Bearing OK.

Step 5 — Block Shear (web plate): Ant = (70 - 0.5×22) × 11.6 = 59 × 11.6 = 684 mm^2 Agv = (3×70 + 50) × 11.6 = 260 × 11.6 = 3,016 mm^2 Tr_block = 0.90 × (0.60 × 350 × 3,016 + 450 × 684) / 1000 = 0.90 × (633 + 308) = 847 kN > 350 kN. OK.

Result: W610×155 beam splice with 230×22 flange plates and 10 mm web plates, M22 A325M SC-B bolts. All limit states satisfied per CSA S16:24.

Frequently Asked Questions

Where should a beam splice be located for best efficiency? Beam splices should be placed at points of low bending moment — typically L/4 from the support for simply supported beams, or at inflection points (~0.21L from support) for continuous beams. At L/4, the moment is approximately 19-24% of the peak midspan moment, minimizing the flange force that the splice must transfer. For transportation-limited beams (12-18 m), two splices per beam at the third points may be optimal.

When are slip-critical bolts required for beam splices? Per CSA S16 Clause 13.12.3, slip-critical bolts are required when: (a) the connection is subject to fatigue loading or stress reversal, (b) slip would impair structural performance (e.g., at braced frame connections), or (c) the splice is in a hybrid girder where the joint must behave monolithically. For typical static building beam splices, bearing-type bolts are acceptable unless the beam is part of the lateral load-resisting system.

What is the advantage of a CJP welded splice over bolted? CJP welded splices develop the full capacity of the connected sections with no bolts, plates, or slip checks. They are the preferred choice for highly-loaded moment splices where the flange force exceeds practical bolt arrangements. However, CJP splices require qualified welders per CSA W59, preheat for thick sections, NDT (UT or RT), and are more expensive to execute in the field. Bolted splices are more common for field connections due to simpler QA/QC.

How is block shear checked for splice plates? Per CSA S16 Clause 13.11, block shear in splice plates follows the same procedure as gusset plates: Tr = 0.90 × min(U × F_u × A_nt + 0.60 × F_y × A_gv, U × F_u × A_nt + 0.60 × F_u × A_nv). For splice plates, multiple bolt rows in shear typically result in a tear-out pattern that spans the full bolt group. Check both the flange plate and the web plate for block shear.

Related Pages

• CSA S16 Beam Design Guide
• CSA S16 Bolt Design Guide
• CSA S16 Weld Capacity Reference
• CSA S16 Weld Inspection
• CSA S16 Column Design
• Bolted Connection Calculator
• All Canadian References

This page is for educational reference. Beam splice design per CSA S16:24 Clauses 13 and 14 and CSA W59 welding requirements. Verify splice location, design forces, and bolt/weld capacities with project structural engineer. Results are PRELIMINARY — NOT FOR CONSTRUCTION without independent PE/SE verification.

Design Resources

Calculator tools

• Bolted Connection Calculator
• Weld Capacity Calculator
• End Plate Moment Connection Calculator
• Fin Plate Shear Connection Calculator
• Beam Capacity Calculator

Design guides

• Bolted Connection Worked Example
• Bolted Connection Checklist
• Weld Design Checklist
• Steel Connection Calculator Guide
• How to Verify Calculations

Reference pages

• CA Bolt Bearing & Tearout
• CA Shear Tab Design
• CA End Plate Connection