Introduction: The Heart of Structural Continuity
Steel frame moment connection design dictates PEB survival. You fabricate the primary portal frame in segments. You join them on-site. The knee splice (SPL-1). The ridge splice (SPL-2). These rigid joints must instantly transfer massive bending moments (M), axial forces (N), and shear forces (V). Joint failure equals catastrophic building collapse. Zero margin for error.
1. High-Strength Bolt Assembly Specifications (Grade 10.9S)
We exclusively specify Grade 10.9S Large Hexagon Head Bolt Assemblies (GB/T 1228 / GB/T 1231) for moment splices. No exceptions. One bolt. One heavy hex nut. Two hardened flat washers. The engineering data is absolute.
| 螺栓规格 (Bolt Spec) | 螺距 (Pitch, mm) | 垫圈下头部高 (K, mm) | 设计预拉力 (P0, kN) | 抗拉强度 (fub, MPa) |
| M16 | 2.0 mm | 10.0 mm | 100 kN | 1040 MPa |
| M20 | 2.5 mm | 12.5 mm | 155 kN | 1040 MPa |
| M22 | 2.5 mm | 14.0 mm | 190 kN | 1040 MPa |
| M24 | 3.0 mm | 15.0 mm | 225 kN | 1040 MPa |
| M27 | 3.0 mm | 17.0 mm | 290 kN | 1040 MPa |
| M30 | 3.5 mm | 18.7 mm | 355 kN | 1040 MPa |
2. Connection Modality: Friction-Type vs. Bearing-Type
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Friction-Type (Slip-Critical): Dynamic loads. Overhead cranes. Seismic zones. This relies entirely on the frictional resistance of clamped contact surfaces. Slip coefficient μ ≥ 0.40 is mandatory. You must verify this on-site. Three standard friction test specimens (Part No. 902438) ship with every project.
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Bearing-Type: Shank shear and hole wall bearing. Specify this for standard static gravity loads only.
3. Standard Bolt Hole Tolerances
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Primary Splice Holes: +1.5mm absolute tolerance. M16 dictates Ø17.5mm. M20 dictates Ø21.5mm. M24 requires Ø25.5mm. Too tight? Installation fails. Too loose? Structural slip.
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Foundation Anchor Bolt Holes: Strictly +6.0 mm. Concrete placement is never perfectly accurate. This gap absorbs the variance.
4. Flange Plate Geometric Splicing Rules
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Thickness Transition: The 4mm rule. When T2 – T1 > 4 mm, the thicker plate demands a 1:4 slope bevel machine cut. Only then can you execute the full-penetration butt weld.
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Width Transition: When W2 – W1 > 4 mm, a 1:4 slope transition cut across the width is mandatory.
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Ridge Outer Flange (SPL-2): Roof slope < 3% and flange thickness t ≤ 10 mm? Run the outer flange continuously. Slope ≥ 3% or t > 10 mm? Cut and splice. Period.
5. High-Strength Bolt Assembly Parts Matrix
| 零件号 (Part No.) | 规格型号 (Description) | 最大连接板厚 (Max Grip) | 螺栓长度 (Length) | 单套重量 (Unit Wt, kg) |
| G902274 | M16X50 H.S. Large Hex (10.9S) | 21 mm | 50 mm | 0.2296 kg |
| G902275 | M16X60 H.S. Large Hex (10.9S) | 31 mm | 60 mm | 0.2445 kg |
| G902278 | M20X60 H.S. Large Hex (10.9S) | 27 mm | 60 mm | 0.4192 kg |
| G902280 | M20X80 H.S. Large Hex (10.9S) | 47 mm | 80 mm | 0.4684 kg |
| G902282 | M20X100 H.S. Large Hex (10.9S) | 67 mm | 100 mm | 0.5203 kg |
| G902283 | M22X60 H.S. Large Hex (10.9S) | 22 mm | 60 mm | 0.5182 kg |
| G902285 | M22X80 H.S. Large Hex (10.9S) | 42 mm | 80 mm | 0.5778 kg |
| G100065 | M24X70 H.S. Large Hex (10.9S) | 30 mm | 70 mm | 0.7067 kg |
| G902288 | M24X80 H.S. Large Hex (10.9S) | 40 mm | 80 mm | 0.7428 kg |
| G902290 | M24X100 H.S. Large Hex (10.9S) | 60 mm | 100 mm | 0.8159 kg |
| G902294 | M27X100 H.S. Large Hex (10.9S) | 57 mm | 100 mm | 1.0873 kg |
| G902298 | M30X100 H.S. Large Hex (10.9S) | 53 mm | 100 mm | 1.3532 kg |