Flexural collapse in over-reinforced beam is due to Secondary Compression Failure.

Explanation:
- Flexural collapse in a reinforced concrete beam refers to the failure of the beam due to bending (flexure) stress.
- When a beam is over-reinforced, the amount of steel reinforcement is higher than the amount required to resist the maximum bending moment that the beam can experience.
- In such a case, the concrete in the compression zone of the beam fails before the steel reinforcement reaches its yield stress.
- This type of failure is called secondary compression failure because it occurs due to the crushing of concrete in the compression zone, after the steel reinforcement has already yielded.
- The beam fails in a ductile manner, with the steel reinforcement undergoing significant plastic deformation before the final collapse.
- In contrast, in a normally reinforced beam, the concrete in the compression zone fails before the steel reinforcement yields, leading to a brittle failure.

In summary, flexural collapse in an over-reinforced beam is due to secondary compression failure, which occurs when the concrete in the compression zone of the beam fails after the steel reinforcement has already yielded.

Flexural collapse in over-reinforced beam is due to secondary compression failure. This means that the beam fails due to the crushing of concrete in the compression zone after the steel reinforcement has yielded.

Explanation:

Over-reinforced beams are those in which the amount of steel reinforcement is greater than the amount required for balanced design. In such beams, the steel reinforcement reaches its yield strength before the concrete reaches its ultimate strength. This results in the formation of plastic hinges near the supports of the beam.

When the plastic hinges are formed due to the yielding of steel reinforcement, the concrete in the compression zone starts to crush. This is because the concrete cannot withstand the increased compressive stresses caused by the yielding of steel. The crushing of concrete causes the beam to lose its load-carrying capacity, leading to flexural collapse.

Secondary compression failure occurs after the primary compression failure, which is the initial crushing of concrete in the compression zone. Secondary compression failure occurs when the stress in the concrete increases due to the yielding of steel reinforcement, causing the concrete to crush further. This results in the formation of a larger plastic hinge and the eventual collapse of the beam.

In summary, the flexural collapse in over-reinforced beams is due to secondary compression failure, which occurs when the concrete in the compression zone of the beam crushes further after the steel reinforcement has yielded.