The maximum area of tension reinforcement in beams shall not exceed

Explanation:

Maximum Area of Tension Reinforcement in Beams

The maximum area of tension reinforcement in beams is restricted to ensure the ductile behavior of the structure. Excessive reinforcement can lead to brittle failure, which is undesirable in structural design. According to IS 456:2000 (Indian Standard for Plain and Reinforced Concrete), the maximum area of tension reinforcement is governed by the following:

• Purpose: To maintain balanced ductile behavior and avoid congestion of reinforcement.

• Maximum Limit: The code specifies that the maximum area of tension reinforcement should not exceed 0.04 times the gross cross-sectional area of the beam (bD).

Analyzing the Given Options

1. "0.04bD" (Correct Answer)

   • The value 0.04bD is in accordance with IS 456:2000 and ensures balanced ductile behavior of the beam.

   • It also prevents excessive congestion of reinforcement, allowing proper placement and compaction of concrete.

2. "0.02bD" (Incorrect)

   • While 0.02bD is within the permissible range for minimum reinforcement, it is not the maximum limit.

   • This value is primarily used to ensure that the beam does not fail in tension before the concrete's cracking moment.

3. "0.08bD" (Incorrect)

   • 0.08bD exceeds the permissible limit set by the code (IS 456:2000), making it unsafe and non-compliant.

   • Such a high percentage of reinforcement can lead to brittle failure and difficulty in placing and compacting the concrete.

4. "0.10bD" (Incorrect)

   • 0.10bD is far beyond the allowable limit, resulting in significant over-reinforcement.

   • Over-reinforcement reduces ductility and makes the beam susceptible to sudden and brittle failure.

Conclusion: The correct answer is Option 1: 0.04bD, as it complies with IS 456:2000 and ensures safe and ductile behavior of reinforced concrete beams.