The permissible maximum shear stress τvm for a steel beam should not exceed (where fy is yield stress of steel.)
- A0·36 fy
- B0·45 fyCorrect
- C0·65 fy
- D0·87 fy
Solution
Concept
Permissible shear stress in working stress design
Formula
τvm = 0.45 fy
Step-by-step solution
1. Permissible bending stress = 0.66 fy. 2. Permissible average shear stress = 0.40 fy; permissible maximum shear stress = 0.45 fy.
Explanation
In working stress design of steel (IS 800:1984), the maximum shear stress in a beam is limited to 0.45 fy.
Why the other options are wrong
0.36 and 0.65 are not the shear stress limits, and 0.87 fy is the limit state design stress for steel in RCC.
Shortcut
Bending 0.66 fy; shear max 0.45 fy; average 0.40 fy.
Common mistake
Choosing 0.66 or 0.87.
Correct answer: B) 0·45 fy