Design procedure of singly RCC section as per IS 456: 2000 ?

Before moving into the design procedure of a R.C.C beams you should be aware about the different types of beams available. There are basically seven types of beam depending upon the support and geometry of the beam section, they are:

  1. Simply supported beam
  2. Fixed beam
  3. Overhanging beam
  4. Double over hanging beam
  5. Continuous beams
  6. Cantilever beams
  7. Trussed beams

Check this post to know more about these beams

The design procedure of each beam is different only the underlying principle is the same. In this post I will explain about the step by step procedure of design of a simply supported beam, by considering an example problem.

Problem Statement : Design a simply supported beam with cross section of 300 mm X 500 mm, subjected to a bending moment of 100 KNm. Assume effective cover = 30 mm and use M20 concrete and Fe415 steel.

Given data as per the design problem:

  • breadth(b) = 300 mm
  • depth (d) = 500 – 30 = 470 mm
  • M = 100 KNm
  • fck = 20 N/ mm2
  • fy =415 N/ mm2
  • Depth of neutral axis: xumax = 0.48 * d = 225.6 mm – for Fe415 steel

Calculate the value of moment of resistance

$$
M_{u,lim} =0.36 f_{ck}\frac{ X_{umax} }{d}(1-0.42 \frac{X_{umax}}{d}) {bd}^{2}
$$

$$M_{u,lim}= 182.86 KNm$$

Calculate the design moment

Design moment

$$
M_{u}=M \times \gamma_{f} = 100 \times 1.5 =150 KNm
$$

Therefore for this case Mu,lim > Mu ; so it is a under reinforced beam section.

Calculate the area of reinforcement (Ast)

$$
M_{u} =0.87 \times fy \times \text { Ast } \times d\left(1-\frac{fy \text { Ast }}{fck\times b \times d}\right)
$$

$$
150 \times 10^{6}=0.87 \times 415 \times \text { Ast } \times 470\left(1-\frac{415 \text { Ast }}{20 \times 300 \times 470}\right)
$$

$$
\text { Ast }=600 \mathrm{~mm}^{2} (approx)
$$

Do check this post to know the design procedure for a doubly reinforced beam.

Beam design

  • RCC Beam Design is a free app for designing reinforced concrete beams as per Indian Standards.
  • RCC Design and detailing could be performed by Limit State Method specified in IS456:2000
  • Option to save the design projects in local storage.
  • Detailed calculation steps presented for verification and validation.
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