Nominal shear capacity of a bolt is 82335 N. What is the design capacity of the bolt, if slip resistance is designated at service load?
- A82335 N
- B74850 NCorrect
- C449.099 N
- D395.208 N
Solution
Concept
Design capacity = nominal capacity divided by partial safety factor γmf. As per IS 800:2007, γmf = 1.10 when slip resistance is designated at service load.
Formula
Vdsf = Vnsf / γmf
Step-by-step solution
1. Nominal slip resistance Vnsf = 82335 N. 2. Slip resistance is designated at service load, so γmf = 1.10 (IS 800:2007). 3. Vdsf = 82335 / 1.10 = 74850 N.
Explanation
For friction type (HSFG) bolts, design capacity is nominal capacity divided by γmf. When slip is checked at service load, γmf = 1.10. So design capacity = 82335 / 1.1 = 74850 N.
Why the other options are wrong
A: no partial safety factor is applied. C: value is far too small and has no basis. D: value is far too small and has no basis.
Shortcut
Service load: divide by 1.1. Ultimate load: divide by 1.25.
Common mistake
Using γmf = 1.25 (ultimate load case) or γmb = 1.25 instead of 1.10 for the service load case.
Correct answer: B) 74850 N