Minimum and Maximum Reinforcement in Beam

4 April 2022

Minimum and Maximum Reinforcement in Beam is given in IS 456 2000 

ØAsmax = 4%bD        (Max Reinforcement in Beam)
ØAsmin = 0.85 bd/fy   (Max Reinforcement in Tension)

 For Understanding with an Example
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The code specifies the percentage of reinforcement to be used in Beam for both Max and Min.

But in general, there are many types of reinforcement used in beam-like

  • Tension Reinforcement
  • Compression Reinforcement
  • Shear Reinforcement and many more

In this blog, we will focus on Min Reinforcement in Tension Reinforcement and also the max reinforcement overall.

  • Min Reinforcement in Tension Reinforcement

The Min reinforcement is specified in IS Code as the added image.

But if you are anything like me we can not able to understand by it so we can explain it by example


Min Reinforcement in Beam

Let us assume you have a Beam 3 m in Length with its cross-section of 200 mm x 300 mm 

Asmin = 0.85 bd/fy

As we Know b=200mm  d=300- Effective Cover ( but effective cover depends on bar dia also so for simplification and for better safety we take over all depth d ≈ D=300 ) and Fy = characteristic strength of steel reinforcement = 415 )

So Asmin = 0.85* 200*350 / 415 = 143.3 mm2

So, min Number of Bar Will be =Asmin / Area of one bar 

Cross Section Min Area Of Steel Min Number as per Dia Of bar
b D As min 8 10 12
200 300 125.8 3 2 2
200 350 146.7 3 2 2
200 400 167.7 4 2 2
200 450 188.7 4 2 2
200 500 209.6 5 2 2
250 300 157.2 4 2 2
250 350 183.4 4 2 2
250 400 209.6 5 2 2
250 450 235.8 5 2 2
250 500 262.0 6 2 2

  • Max Reinforcement in  Reinforcement

 The Max reinforcement is specified in IS Code as the 4 percent of gross area.

 Asmax = 4%bD = 4/100*200*350 = 2800 mm2

Cross Section Max Area Of Steel Min Number as per Dia Of bar
b D As max 8 10 12
200 300 2400.0 48 31 22
200 350 2800.0 56 36 25
200 400 3200.0 64 41 29
200 450 3600.0 72 46 32
200 500 4000.0 80 51 36
250 300 3000.0 60 39 27
250 350 3500.0 70 45 31
250 400 4000.0 80 51 36
250 450 4500.0 90 58 40
250 500 5000.0 100 64 45

We hope, you understand how to find  Minimum and Maximum Reinforcement in Beam. to find such Informative concepts and practical knowledge-Visit Here!

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