Correct option is B
Sill Beam:
A sill beam is a horizontal beam provided at the bottom of the window opening.
It distributes the loads uniformly and prevents the concentration of stresses around the window corners, which is the primary cause of diagonal cracks.
It is an economical solution compared to RCC frames or altering the window shape.
Why Not the Other Options?
(a) Providing RCC frame all around the rectangular opening: While effective, it is a costlier solution compared to a sill beam.
(c) Using concrete blocks for wall instead of bricks: This does not directly address the issue of stress concentration around window corners.
(d) Providing circular-shaped window openings: Circular openings reduce stress concentration but involve higher costs and design complexities.
