What is a under-reinforced section in design of beam?

Answer 1

An under-reinforced section in beam design refers to a concrete beam that has insufficient tensile reinforcement to prevent failure by yielding of the steel before crushing of the concrete. This condition is typically characterized by a lower ratio of steel reinforcement to the amount of concrete, resulting in a ductile failure mode. In such a scenario, the steel reinforcement reaches its yield strength before the concrete reaches its ultimate compressive strength, allowing for some warning before failure occurs. This design approach is often preferred as it provides a more predictable and safer collapse mechanism.