In a ring beam subjected to uniformly distributed load
(i) Shear force at mid span is zero. $^{c}$
(ii) Shear force at mid span is maximum.
(iii) Torsion at mid span is zero.
(iv) Torsion at mid span is maximum.

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This question was previously asked in

JKSSB JE (Civil) Official Paper (Held On: 19 Nov, 2023)

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Answer 1

Explanation:

A ring beam is a closed circular beam subjected to a uniformly distributed load (UDL) along its span (such as from walls or roof loads).
In a circular ring beam under UDL, the shear force is zero at the crown (mid-span).
This is because the vertical component of load is balanced symmetrically at that point; no net transverse shear remains.
In a ring beam under symmetric UDL, torsional moments are maximum at supports (e.g., quarter spans or support points).
At the crown/mid-span, torsional effects from both sides cancel each other out, so torsion is zero there.

Additional Information

Shear Force in Circular Beams: In circular beams or ring beams under uniformly distributed load (UDL), shear force varies along the span. It is maximum near the supports and zero at the crown (mid-span) due to symmetry. This behavior is opposite to straight beams where maximum shear occurs at supports but not necessarily zero at mid-span.
Torsion in Ring Beams: Torsional moments develop in ring beams because the beam tends to twist due to the curvature and the eccentric nature of loading. Torsion is zero at the crown but maximum at support points or quarter-span locations. The torsional effect must be considered in design, especially when the beam supports walls or roofs.
Bending Moment in Ring Beams: Bending moment in a ring beam due to UDL is maximum at mid-span (crown). The curvature causes a moment that resists the vertical load, and this moment is symmetrically distributed. The design must accommodate this maximum moment with proper reinforcement.
Importance of Ring Beams in Structures: Ring beams are crucial in circular structures like water tanks, silos, chimneys, or domes. They help to distribute radial loads uniformly, resist torsional and bending moments, and maintain the shape and stability of the structure. Proper detailing of shear, torsion, and bending reinforcement is essential for structural integrity.