IQEG CALCULATION LAB
Bolt group forces
IQ-CAL-013 · Rev 0 Indicative · 11/11/2026 · Not a certificate
IQ Engineering Group · Sydney · IQ-CAL-013 · Bolt group forces · millimetres, kN, kNm, MPa unless noted
Arrangement
Actions at the group centroid C. Toggle bolts on the drawing or below. Pitch is centre-to-centre.
Glossary
- px, py
- Pitch centre-to-centre, mm. The picture is a fixed grid — only the notes update.
- Ixx, Iyy
- Σ y² and Σ x² of the bolts that are on, mm².
- Mz
- In-plane torsion. Side-plate eccentricity e: Mz = V e.
- Toggle
- Click a bolt on the drawing or the chips to omit it. C moves.
Toggle bolts
Bolt group · x–x / y–y
Elastic point group. Gold fill = bolt on. Open circle = omitted. Red ring = governing. C is the centroid of bolts that are on. Actions at C: Vx 40 kN, Vy 40 kN, N 200 kN, Mxx 18 kNm, Myy 10 kNm, Mz 0 kNm. Four bolts, square. Typical UC base or cap. Compression + biaxial moment + shear.
Capacity
Elastic, all bolts. Compression is counted in the N distribution. The tension check uses max(N, 0). Not a T-stub / prying / plastic analysis.
Calculation · separated by action
- 01
One-bolt capacities for the selected grade and size. φ = 0.80. Threads in plane use As; shank uses An.
M20 8.8 fu = 830 MPa ns = 1 threads IN (As) φNtf = 162.7 kN φVf = 100.9 kN - 02
Centroid C of the n bolts that are on. Ixx = Σ y², Iyy = Σ x² about C. J = Ixx + Iyy. Each bolt is a unit point.
n = 4 C (0.0, 0.0) mm Ixx = 19,600 mm² Iyy = 19,600 mm² J = 39,200 mm² - 03
Direct actions shared equally. N is normal to the plate (tension positive). Vx, Vy are in-plane shear.
N/n = 200 / 4 = 50.00 kN Vx/n = 40 / 4 = 10.00 kN Vy/n = 40 / 4 = 10.00 kN - 04
Moments at a bolt (x, y) from C. Mxx and Myy produce axial force. Mz produces in-plane shear. Units: kNm × 1000 × mm / mm² = kN.
Governing B4 at (70.0, 70.0) x = 70.0 y = 70.0 mm from C N(Mxx) = Mxx·y / Ixx = 18×10³ × 70.0 / 19,600 = 64.29 kN N(Myy) = Myy·x / Iyy = 10×10³ × 70.0 / 19,600 = 35.71 kN Vx(Mz) = −Mz·y / J = -0.00 Vy(Mz) = Mz·x / J = 0.00 kN - 05
Combine. Axial N_i = N/n + N(Mxx) + N(Myy). Shear V_i = √(vx² + vy²). Tension check uses Nt = max(N_i, 0).
N = 50.00 + 64.29 + 35.71 = 150.00 kN Nt = max(N, 0) = 150.00 kN vx = 10.00 + -0.00 = 10.00 vy = 10.00 + 0.00 = 10.00 V = √(vx² + vy²) = 14.14 kN - 06
AS 4100 circular interaction on the governing bolt. Compression does not reduce shear capacity here.
(V/φVf)² + (Nt/φNtf)² = (14.14/100.9)² + (150.00/162.7)² = 0.870 PASS · util 0.870
Per-bolt forces
4 of 4 on · M20 8.8 · φNtf 162.7 kN · φVf 100.9 kN. Highlighted row is governing.
| Bolt | x mm | y mm | N(N) | N(Mxx) | N(Myy) | N kN | vx | vy | V kN | util |
|---|---|---|---|---|---|---|---|---|---|---|
| B1 | -70.0 | -70.0 | 50.0 | -64.3 | -35.7 | -50.0 | 10.0 | 10.0 | 14.1 | 0.020 |
| B2 | 70.0 | -70.0 | 50.0 | -64.3 | 35.7 | 21.4 | 10.0 | 10.0 | 14.1 | 0.037 |
| B3 | -70.0 | 70.0 | 50.0 | 64.3 | -35.7 | 78.6 | 10.0 | 10.0 | 14.1 | 0.253 |
| B4 | 70.0 | 70.0 | 50.0 | 64.3 | 35.7 | 150.0 | 10.0 | 10.0 | 14.1 | 0.870 |