As per IS:800-1984, the maximum thickness of plate girder web plate should not be less than _______ for vertically stiffed webs. (Where d = clear depth of plate girder)
- Ad / 85
- Bd / 200Correct
- Cd / 250
- Dd / 400
Solution
Concept
Minimum web thickness of plate girders
Formula
t = d / 200
Step-by-step solution
1. As per IS:800-1984 specifications for plate girders, web thickness limits prevent elastic web buckling. 2. For webs with vertical stiffeners only, the thickness shall not be less than d / 200, where d is the clear depth of the web. 3. Therefore, the minimum web thickness required for vertically stiffened webs is d / 200. Answer: B
Explanation
According to IS:800 specifications, when vertical stiffeners are provided to reinforce a plate girder web against shear buckling, the web thickness must maintain a minimum ratio relative to clear depth. To ensure the web does not buckle locally prior to yielding, its thickness must not be less than d / 200. Thus, option B is the correct specified limit under this standard.
Why the other options are wrong
A) The ratio d / 85 represents the maximum web thickness limit for unstiffened web plates. C) The ratio d / 250 is specified for webs provided with both vertical and horizontal stiffeners. D) The ratio d / 400 is applicable when additional horizontal stiffeners are placed at the neutral axis.
Shortcut
Vertically stiffened web min thickness = d / 200.
Common mistake
Confusing the thickness requirement for vertically stiffened webs (d/200) with unstiffened or horizontally stiffened webs.
Correct answer: B) d / 200