Compression Failure in Over Reinforced Concrete Beam

In a concrete beam, the failure can occur in different modes depending on the applied loads and the design of the beam. One of the failure modes is compression failure, which is the correct answer in this case.

Compression Failure:
Compression failure occurs when the concrete in a beam is subjected to excessive compressive forces, leading to the failure of the beam. This failure mode is often seen in over reinforced concrete beams.

Causes of Compression Failure:
Several factors can contribute to compression failure in over reinforced concrete beams:

1. Excessive Reinforcement: Over reinforced beams have more steel reinforcement than what is required for balanced design. This excessive reinforcement reduces the amount of concrete available to resist compressive forces. As a result, when the beam is loaded, the concrete in compression reaches its maximum strength and fails before the steel reinforcement can yield.

2. Brittle Behavior of Concrete: Concrete has relatively low tensile strength compared to its compressive strength. Therefore, when the beam is subjected to excessive compressive forces, the concrete undergoes brittle failure due to the inability to withstand the applied load.

3. Inadequate Concrete Strength: If the concrete used in the beam has a lower compressive strength than what is required for the anticipated loads, it may fail under compression before the steel reinforcement yields.

4. Insufficient Cross-Sectional Area: In some cases, the cross-sectional area of the concrete beam may not be sufficient to resist the applied compressive forces. This can occur due to inadequate design or construction errors.

Consequences of Compression Failure:
When a concrete beam fails in compression, it often results in sudden and catastrophic failure. The beam may crack, deform, or collapse entirely, leading to potential damage to the structure and posing a safety risk to occupants.

Conclusion:
In summary, the failure of an over reinforced concrete beam is primarily due to compression failure. This occurs when the concrete is subjected to excessive compressive forces, resulting in the failure of the beam. Factors such as excessive reinforcement, brittle behavior of concrete, inadequate concrete strength, and insufficient cross-sectional area can contribute to compression failure. It is crucial to properly design and reinforce concrete beams to avoid compression failure and ensure the structural integrity of the overall construction.