KEVOS® MAKEOS · Fasteners
Eccentric Bracket Bolt Check (Bolt Group Forces, Shear and Bearing Stress)
For a bracket bolted with a group of bolts and loaded off-centre, which bolt carries most, and are its shear stress and the plate bearing stress within limits?
Check of a bolted bracket with an eccentric load in the plane of the bolts: the centroid of the bolt group, the moment of the load about it, the direct and torsional force on each bolt and the most heavily loaded bolt (as the eccentric bolt group tool), then the shear stress in that bolt and the bearing stress it puts on the plate (as the bolt shear and bearing tool), against your allowable stresses.
Open the calculatorRuns in your browser. No account needed.
How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Number of bolts | bolts | Number of bolts in the group (the first n positions are used). |
| Bolt 1 | ||
| X | mm | X position of bolt 1. |
| Y | mm | Y position of bolt 1. |
| Bolt 2 | ||
| X | mm | X position of bolt 2. |
| Y | mm | Y position of bolt 2. |
| Bolt 3 | ||
| X | mm | X position of bolt 3. |
| Y | mm | Y position of bolt 3. |
| Bolt 4 | ||
| X | mm | X position of bolt 4. |
| Y | mm | Y position of bolt 4. |
| Bolt 5 | ||
| X | mm | X position of bolt 5. |
| Y | mm | Y position of bolt 5. |
| Bolt 6 | ||
| X | mm | X position of bolt 6. |
| Y | mm | Y position of bolt 6. |
| Load | ||
| Load X component | kN | Horizontal component of the load. |
| Load Y component | kN | Vertical component of the load (negative downwards). |
| Load X position | mm | X position of the load’s line of action. |
| Load Y position | mm | Y position of the load’s line of action. |
| Bolts and plate | ||
| Bolt diameter at the shear plane | mm | Bolt diameter where it is sheared (shank or thread). |
| Shear planes per bolt | choice | Whether each bolt is sheared once or twice. |
| Thinnest plate thickness in bearing | mm | Thickness of the thinnest plate the bolts bear on. |
| Allowable bolt shear stress | MPa | Allowable shear stress of the bolts. |
| Allowable bearing stress | MPa | Allowable bearing stress of the plate. |
Method and formulas
- Centroid of the bolts; polar moment J = Σ r²; moment of the load about the centroid (as the eccentric bolt group tool).
- Each bolt: direct share P ÷ n plus M r ÷ J perpendicular to its radius; the largest resultant governs.
- Shear stress = F ÷ (planes × π d² ÷ 4); bearing stress = F ÷ (d t) (as the bolt shear and bearing tool).
- Example: bolt 2 carries 21.506 kN, giving 106.96 MPa shear and 134.41 MPa bearing.
Limitations
- Elastic method with rigid plates; the instantaneous-centre method gives more capacity.
- Bolts in bearing (no slip-critical friction).
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Check a bracket carrying an offset load
- Find the critical bolt in a connection
- Choose bolt size and plate thickness for a bracket
Who it is for
- Design engineers
- Structural detailers
- Fabrication engineers
What you get
- Group centroid and moment
- Force on each bolt and the critical bolt
- Shear and bearing stress of the critical bolt
Interpreting the result
- Spreading the bolts further from the centroid cuts the moment share faster than adding bolts near it.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 1535, 1720–1735. Topic reference; no source tables or recommended settings are reproduced.
WORKOS tools are screening and decision-support utilities. Verify important financial, engineering, safety, legal or operational decisions using appropriate professional standards and your organisation’s approved data.
Open the Eccentric Bracket Bolt Check (Bolt Group Forces, Shear and Bearing Stress) calculator
