Steel · Connections: moment & splices
Bolted flange splice (cover plates) calculator
Flange force from moment and axial share; outer cover plate tension yield/fracture and short-column compression; bolts in single shear.
Standard: AS 4100 Cl 9.1.4, 7.2, 9.3 (simplified)
Inputs in the worked example
The live calculator starts with these values; change any of them and every result, check and diagram updates instantly.
| Input | Value | Unit |
|---|---|---|
| Design moment at splice M* | 300 | kNm |
| Axial force (tension +) | 0 | kN |
| Beam depth | 460 | mm |
| Flange thickness | 14.5 | mm |
| Flange width | 190 | mm |
| Gross section area | 9520 | mm² |
| Cover plate width | 190 | mm |
| Cover plate thickness | 16 | mm |
| Plate grade | Grade 250 plate | |
| Bolts each side of joint (per flange) | 6 | |
| Holes across a section | 2 | |
| Bolt pitch | 70 | mm |
| Bolt size | M24 | |
| Bolt category | 8.8/S |
Worked example — results
| Result | Value | Unit |
|---|---|---|
| Bolt diameter df | 24.00 | mm |
| Bolt tensile strength fuf | 830.0 | MPa |
| Tensile stress area As | 353.0 | mm² |
| Core area Ac (threads) | 324.0 | mm² |
| Shank area Ao | 452.0 | mm² |
| Plate yield stress fy (AS/NZS 3678) | 250.0 | MPa |
| Plate tensile strength fu | 410.0 | MPa |
| Flange force M/(d − tf) + N·bf tf/A | 673.4 | kN |
| Hole diameter | 26.00 | mm |
| Plate gross area | 3,040 | mm² |
| Plate net area | 2,208 | mm² |
| φNt = 0.9 min(Ag fy, 0.85 An fu) | 684.0 | kN |
| Plate λn over 0.6·pitch | 9.09 | |
| φNc (αc ≈ 1 if λn < 25) | 684.0 | kN |
| Bolt group capacity nb·min(φVf, φVb) | 800.3 | kN |
- ✓ Cover plate tension
- ✓ Cover plate compression
- ✓ Bolts
Method, formulas and assumptions
- Bolt diameter df = CHOOSE(4,12,16,20,24,30,36) = 24 mm
- Bolt tensile strength fuf = IF(2=1,400,830) = 830 MPa
- Tensile stress area As = CHOOSE(4,84.3,157,245,353,561,817) = 353 mm²
- Core area Ac (threads) = CHOOSE(4,76.2,144,225,324,519,759) = 324 mm²
- Shank area Ao = CHOOSE(4,113,201,314,452,707,1018) = 452 mm²
- Plate yield stress fy (AS/NZS 3678) = CHOOSE(1,IF(16<=8,280,IF(16<=12,260,250)),IF(16<=8,320,IF(16<=12,310,IF(16<=20,300,280))),IF(16<=12,360,IF(16<=20,350,340))) = 250 MPa
- Plate tensile strength fu = CHOOSE(1,410,430,450) = 410 MPa
- Flange force M/(d − tf) + N·bf tf/A = ABS(300*1000/(460-14.5)+0*190*14.5/9520) = 673.4 kN
- Hole diameter = 24+2 = 26 mm
- Plate gross area = 190*16 = 3040 mm²
- Plate net area = 3040-2*26*16 = 2208 mm²
- φNt = 0.9 min(Ag fy, 0.85 An fu) = 0.9*MIN(3040*250,0.85*2208*410)/1000 = 684 kN
- Plate λn over 0.6·pitch = 0.6*70/(16/SQRT(12))*SQRT(250/250) = 9.0933
- φNc (αc ≈ 1 if λn < 25) = 0.9*3040*250*IF(9.0933<25,1,0.9)/1000 = 684 kN
- Bolt group capacity nb·min(φVf, φVb) = 6*MIN(0.8*0.62*830*324/1000,0.9*3.2*24*MIN(16,14.5)*410/1000) = 800.31 kN
Related steel calculators
- Bolted moment end plate (extended, 8.8/TB) — Extended end plate on a UB beam framing into a UC column flange. The flange force M*/(d − tf) goes to the…
- Flush end plate moment connection — Bolt tension from elastic distribution about the compression flange, end plate thickness from a…
- Extended end plate (4-bolt unstiffened) — Bolt rows either side of the tension flange share the flange force; plate checked as a T-stub…
- Bolted web splice — Web carries the shear plus its share of moment (Iw/I); double web plates; bolt group polar analysis with…
- Butt-welded splice (CP / IP) — Complete penetration butt weld at parent strength, or incomplete penetration treated as a fillet on the…
- Portal knee: column web panel zone — Shear in the column web panel from the rafter moment; diagonal stiffener area required if the web is…
For preliminary design and education. Check every result against the current standard and your own engineering judgement before use.