According to limit state method, what is the maximum area of compression reinforcement in a beam, where d, b and D are the effective depth, width and overall depth of beam respectively?
- A0.04bDCorrect
- B0.04bd
- C0.4bD
- D0.4bd
Solution
Concept
Maximum Compression Reinforcement in Beams
Formula
Asc(max) = 0.04bD
Step-by-step solution
1. Identify the gross cross-sectional area of the beam as b x D. 2. Apply the IS 456:2000 limit state requirement, which specifies that maximum compression reinforcement is 4% of gross area. 3. Calculate 4% of (b x D) = 0.04bD.
Explanation
According to IS 456:2000 standards, the maximum area of compression reinforcement allowed in a beam is 4% of its gross cross-sectional area. Since the gross area is calculated using the total width (b) and overall depth (D), 4% of this area equals 0.04bD.
Shortcut
Remember: 4% = 0.04, and maximum limits for beam steel always use the gross area with Overall Depth (D), giving 0.04bD.
Common mistake
Many students confuse effective depth (d) with overall depth (D) and select 0.04bd (Option B) instead of 0.04bD, or they miscalculate 4% as 0.4 instead of 0.04 and select Option C or D.
Correct answer: A) 0.04bD