Bolt Group Force Calculator
A bolt group under eccentric shear is sized by finding the load demand on the worst bolt. For a circular bolt pattern, the working calculator splits direct shear and moment into per-bolt force components.
Circular bolt group
For equal bolts on a single bolt circle, every bolt has the same radius from the centroid. The moment component is equal in magnitude on every bolt.
F_t = M / (N * R)
Direct shear share
Direct in-plane shear is split equally across the bolts before adding the moment component to the worst bolt.
F_v = V / N
Worst bolt demand
The conservative circular-pattern result adds the direct and tangential components where they line up.
F_max = F_v + F_t
After demand
Use F_max as demand. Compare it with bolt shear capacity, plate bearing, edge distance and any governing code or joint-specific reduction.
Frequently asked questions
Is this for irregular bolt groups?
The working calculator handles a single circular bolt group. Irregular bolt groups use the same elastic method but need each bolt coordinate and distance from the centroid.
Does this calculate bolt capacity?
No. It calculates demand. Use the bolt shear strength and bolt bearing stress calculators for the next checks.
Related pages
- Bolt pattern force calculator - working bolt-group shear demand calculator.
- Bolt shear strength calculator - compare worst-bolt demand against bolt capacity.
- Bolt bearing stress calculator - check plate bearing after the bolt-group force split.
- Bolt circle coordinate calculator - lay out evenly spaced bolt holes on a BCD.
- Weld group calculator - parallel eccentric-load workflow for rectangular weld groups.