Why doubly reinforced beam is less economical?

Doubly reinforced beam is considered less economical because the compression steel in under stressed. so option b is correct. area of steel= c/stress as stress deceases the area increases as they are inversely proportional. In doubly reinforced beam we provide some steel in compression zone to reduce the depth of beam.

Why doubly reinforced beams are preferred?

Why We Use Doubly Reinforced Beam? Doubly reinforced beam is provided to increase the moment of resistance of a beam having limited dimensions. Minimum compression reinforcement is provided to hold the Shear Reinforcement (stirrups) in position and for increasing the ductility of beam.

Under what situation is doubly reinforced beam preferred?

NECESSITY OF DOUBLY REINFORCED SECTION When the loads are eccentric. When the bam is subjected to accidental or sudden lateral loads. In the case of continuous beams or slab, the sections at supports are generally designed as doubly reinforced sections.

What is the doubly reinforced beam?

Doubly reinforced beam is defined as the beam in which the reinforcement is provided by the steel in both tension and compression zone of the beam. If it is known that the depth of the beam is fixed, then the best option is to provide the doubly reinforced beam for resisting the particular moment.

Which beam is more economical singly or doubly?

A doubdly reinforced beam is considered less economical than a singly reinforced beam because. tensile steel required is more than that for a balanced section. shear reinforced is more. concrete is not stressed to its full value.

What is necessity of doubly reinforced section?

Doubly reinforced sections are used in the following conditions: When the dimensions (b x d) of the beam are restricted due to any constraints like availability of head room, architectural or space considerations and the moment of resistance of singly reinforced section is less than the external moment.

Which is economical singly reinforced beam or doubly reinforced beam?

A doubdly reinforced beam is considered less economical than a singly reinforced beam because. tensile steel required is more than that for a balanced section.

Which material fails first in RCC over reinforced beams?

In under reinforced section, the failure is ductile because steel fails first and sufficient warning is given before collapse.