Intermediate vertical stiffeners are provided in plate girders to
- APrevent local buckling
- BPrevent web bucklingCorrect
- CPrevent excessive deflection
- DPrevent flange buckling
Solution
Concept
Purpose of intermediate vertical web stiffeners
Formula
NONE
Step-by-step solution
1. Plate girders are deep structural beams with slender web plates that are vulnerable to shear forces. 2. Under high shear stresses, thin web plates tend to buckle diagonally. 3. Intermediate vertical stiffeners are provided along the length of plate girders to increase shear strength and prevent web buckling. Answer: B
Explanation
Plate girders often have thin webs that are vulnerable to shear buckling under heavy shear stresses. Intermediate vertical stiffeners are attached perpendicular to the flanges to increase the shear capacity of the web by dividing it into smaller panels. This prevents web buckling and allows the girder to safely carry greater loads.
Why the other options are wrong
A) Local buckling of flanges is controlled by flange outstand-to-thickness ratio. C) Excessive deflection is prevented by increasing depth and section modulus. D) Flange buckling is prevented by limiting flange plate width-to-thickness ratio.
Shortcut
Vertical stiffeners prevent thin web plates from shear buckling.
Common mistake
Confusing intermediate vertical stiffeners used for web buckling with bearing stiffeners or flange bucking provisions.
Correct answer: B) Prevent web buckling