Plate Girders MCQ with answer and solution

Concept

Design and function of intermediate vertical stiffeners in plate girders to prevent web buckling under shear.

Step-by-step solution

1. Identify the primary function of plate girder components. 2. Note that the web is susceptible to diagonal buckling under high shear stresses. 3. Intermediate vertical stiffeners divide the web into smaller panels, increasing its buckling resistance against shear. 4. Therefore, they prevent local buckling of the web.

Explanation

Intermediate vertical stiffeners in plate girders are provided to restrain the web against out-of-plane buckling caused by high diagonal compressive stresses resulting from shear forces. Without these stiffeners, thin webs would buckle prematurely under shear.

Why the other options are wrong

B: Flange local buckling is prevented by limiting the out-standing width-to-thickness ratio of the flange. C: Excessive deflection is controlled by providing adequate overall depth and moment of inertia of the girder. D: Bearing strength of the web against concentrated loads is increased by providing load-bearing/bearing stiffeners.

Shortcut

Vertical stiffeners = Shear = Web buckling.

Common mistake

Confusing vertical stiffeners (for shear/web buckling) with bearing stiffeners (for concentrated loads) or horizontal stiffeners (for bending/compression buckling of web).