Eccentricity of load causing shear stress from bolt group centroid.
Polar moment of inertia
$$ I_{bg} = {\left({ n_{c_{bg}} \cdot {n_{r_{bg}} \over 12} }\right) \cdot \left({ s_{r_{bg}} ^ 2 \cdot \left({ n_{r_{bg}} ^ 2 - 1 }\right) + s_{c_{bg}} ^ 2 \cdot \left({ n_{c_{bg}} ^ 2 - 1 }\right) }\right)} $$
Critical bolt horizontal force
$$ F_{3_{bg}} = {P_{bg} \cdot e_{s_{bg}} \cdot \left({ n_{r_{bg}} - 1 }\right) \cdot {s_{r_{bg}} \over \left({ 2 \cdot I_{bg} }\right)}} $$
Vertical bolt force without eccentricity
$$ F_{1_{bg}} = {{P_{bg} \over \left({ n_{c_{bg}} \cdot n_{r_{bg}} }\right)}} $$
Critical bolt vertical force
$$ F_{2_{bg}} = {P_{bg} \cdot e_{s_{bg}} \cdot {s_{c_{bg}} \over \left({ 2 \cdot I_{bg} }\right)}} $$
Calculates required shear or slip resistance of the critical bearing or friction grip bolt in bolt group. SABS0162.
Factored resistance of bearing bolts in shear, Grade 8.8.
Bolt size | Single shear [kN] | Double shear [kN] |
M12 | 27.2 | 54.5 |
M16 | 48.5 | 97 |
M20 | 75.7 | 151 |
M24 | 109 | 218 |
M30 | 171 | 341 |
Factored resistance of friction grip bolts, Grade 8.8S.
Bolt size | Pre-Tension [kN] | Class A | Class B | Class C |
(M12) | 49 | 13.5 | 22.1 | 17.9 |
M16 | 91 | 23.9 | 39.4 | 31.8 |
M20 | 142 | 37.4 | 61.5 | 49.8 |
M24 | 205 | 53.9 | 88.6 | 71.5 |
M30 | 326 | 84.1 | 138 | 112 |
M36 | 475 | 121 | 199 | 161 |
Combined shear force per bolt in a bolt group
$$ F_{R_{bg}} = {\sqrt{ F_{3_{bg}} ^ 2 + \left({ F_{1_{bg}} + F_{2_{bg}} }\right) ^ 2 }} $$