How does skew angle influence bending moments and shear distribution in a bridge deck?

• A. It reduces torsional effects and equalizes the distribution.
• B. Skew angle introduces torsional effects and uneven distribution, increasing negative moments near supports and requiring additional detailing to maintain balance and stiffness.
• C. It has no effect on bending moments.
• D. It only affects live load distribution, not moments.

Answer: (B)

Skew angle introduces torsional effects in the deck-girder system, so bending moments and shear are no longer distributed evenly along the span or across the deck width. Because the load path from the deck to the supports is not aligned with the structural axis, the deck experiences a twisting action as it resists the reaction forces. This twist tends to concentrate bending in certain regions, especially near the supports, elevating negative moments there, and it creates an uneven shear distribution across the deck width, with one edge or region carrying more shear than another. To keep balance and stiffness, additional detailing is required—such as torsion-resisting reinforcement, diaphragms or cross-frames, and edge reinforcement—to counteract the torsion and maintain the overall structural behavior.