Q1: In a singly reinforced beam, if the permissible stress in concrete reaches earlier than that in steel, the beam section is called

ANS:B - over reinforced section

In a singly reinforced beam, if the permissible stress in concrete reaches earlier than that in steel, the beam section is called an under-reinforced section. In an under-reinforced section, the concrete reaches its maximum permissible stress (usually in compression) before the steel reinforcement reaches its maximum permissible stress (usually in tension). This means that the concrete is unable to fully utilize the strength of the steel reinforcement, resulting in an inefficient use of materials. Under-reinforced sections are common in practice and are often desirable because they provide warning signs of impending failure. When a beam is under-reinforced, the steel reinforcement can yield and provide ductile behavior, allowing for warning signs such as cracking and deflection before failure occurs. This behavior is preferred in many structural designs because it provides a more gradual failure mechanism, which is often safer than sudden and brittle failure. Therefore, the correct term for a beam section in which the permissible stress in concrete reaches earlier than that in steel is an under-reinforced section.