Correct Answer - Option 1 :
\(\frac{{Force}}{{Bolt\;value}}\)
Explanation:
To find the number of bolts required in a bolted joint, the force to be resisted is divided by the bolt value.
∴ the answer should be \(\frac{{Force}}{{Bolt\;Value}}\)
Bolt value is the strength of the bolt.
Strength of bolt is taken as the minimum value of the following
- Shearing strength in a bolt
- Bearing strength in a bolt
- Tensile strength in a bolt.
|
Type of Stress
|
Formula
|
|
Shear Strength
|
Vdsb = \(\frac{{{f_{ub}}}}{{\sqrt 3 \times {\gamma _{mb}}}}\)
Vdsb = Shearing Strength of bolt
fub = Ultimate tensile stress of the bolt
γmb = Partial safety factor for the material
|
|
Bearing Strength
|
Vdpb = \(2.5\frac{{{k_b}dt{f_u}}}{{{\gamma _{mb}}}}\)
Vdpb = Bearing strength of bolt
kb = co-efficient;
smaller of (e/3d0 , \(\frac{p}{{3\;{d_0}}} - 0.25\),
fub / fu & 1)
e = end distance
p = pitch distance
d = nominal diameter of bolt
d0 = diameter of bolt hole
t = thickness of the connected plates experiencing bearing stress
fu = ultimate tensile stress of the plate
fub = ultimate tensile stress of the bolt
γmb = Partial safety factor
|
|
Tensile Strength
|
Tdb\(\frac{{0.9\;{f_{ub}}\;{A_{nb}}}}{{{\gamma _{mb}}}}\) < \(\frac{{{f_{vb}}{A_{sb}}{\gamma _{mb}}}}{{{\gamma _{m0}}}}\)
Tdb = Tensile strength
fub = ultimate tensile stress f bolt
fvb = yield stress of bolt
Anb = net tensile area of bolt
Asb = Shank area of bolt
γmb = partial safety factor for material of bolt = 1.25
γm0 = partial safety factor for material resistance governed by yielding = 1.10
|
