A fixed beam of span L is subjected to a central point load P. What are the number of points of contraflexure and their respective positions from the left support?

ByN Lavanya Last modified: December 6, 2023

A) 2 points , at L/4 and 3L/4 from left support
B) 1 point , at L/2 from left support
C) 3 points , at L/3, L/2 and 2L/3 from left support
D) No point of contra flexure

Reference:
As per theory of structural analysis, in a fixed beam with a central point load, there are two points of contraflexure located at a distance of L/4 and 3L/4 from the left support, where L is the span.

fixed beam BMD — Image Source: testbook.com

This is because a fixed beam undergoes double curvature bending under a central point load. The bending moment diagram is symmetric about the centre and changes slope at L/4 and 3L/4 distances. These points of slope change are known as contraflexure points.

Therefore, option A is the correct answer.

N Lavanya

Lavanya is a passionate content writer about Structural Design, Grouting, Columns, Beams etc. She has 5 years of experience in teaching in Civil Engg. She enjoys writing complete guides and tips. Her passion is in building materials, construction standards, foundation design and building codes.

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