In plate girders subjected to uniformly distributed load, the horizontal stiffeners are provided
- ATo resist the uniformly distributed load
- BTo reduce the deflection of girder
- CTo resist the buckling of web in compressionCorrect
- DFor aesthetic purposes
Solution
Concept
Web stiffeners in plate girders
Step-by-step solution
1. Understand the behavior of plate girders under transverse loads. 2. Identify that webs are slender and susceptible to buckling under high shear and compressive stresses. 3. Recognize that vertical intermediate stiffeners resist shear buckling, while horizontal (longitudinal) stiffeners are provided to prevent buckling of the web in compression (especially when the depth of the web is large).
Explanation
In plate girders, webs are thin and prone to buckling due to diagonal compressive stresses induced by shear and bending. Horizontal (longitudinal) stiffeners are provided along the length of the girder to prevent web buckling under compression, particularly in deep girders.
Why the other options are wrong
A: UDL is resisted by the girder as a whole (flanges and web together). B: Deflection is controlled by increasing the overall depth or moment of inertia of the girder. D: Stiffeners are structural elements for stability, not aesthetics.
Shortcut
Horizontal stiffeners = compression buckling resistance of the web.
Common mistake
Confusing horizontal stiffeners with bearing stiffeners or vertical intermediate stiffeners which resist shear buckling.
Correct answer: C) To resist the buckling of web in compression