Point of Contraflexure in a Simply Supported Beam with Uniformly Distributed Load For a simply supported beam carrying a uniformly distributed load w per unit length over the entire span, the point of contraflexure (where bending moment changes sign) __________.

Introduction:Contraflexure is where the bending moment diagram crosses zero (changes sign). This checks understanding of bending moment shapes under distributed loading.

Given Data / Assumptions:

• Simply supported beam.
• UDL w over entire span.
• No intermediate point loads or couples.

Concept / Approach:For a simply supported beam under full-span UDL, shear is linear and bending moment is a concave-down parabola, positive throughout the span (zero only at the supports).

Step-by-Step Solution:Bending moment at supports = 0.Maximum positive moment at midspan: M_max = w * l^2 / 8.Since the moment does not become negative anywhere, the diagram does not cross zero inside the span.

Verification / Alternative check:Drawing the SFD and BMD confirms a purely positive parabolic BMD for UDL on simple supports.

Why Other Options Are Wrong:

• Centre or ends: These suggest specific locations, but the definition requires a sign change which does not occur.
• Depends on length: Length scales the magnitude, not the sign pattern.

Common Pitfalls:Confusing zero bending moment at supports (boundary condition) with an internal sign change point.

Final Answer:does not exist