Solved numerical examples | Design of Singly reinforced sections

Guide to design of Singly reinforced Sections | Building Construction

For the “design of Singly reinforced sections” article series, we have covered the following:


Now we will move on with our next solved numerical example in which we will make use of the formulas that we have derived in our earlier articles.

Numerical Problem

Determine the following:

a)      The position of the neutral axis

b)      Lever arm

c)       Moment of resistance

d)      Percentage of steel

(For a rectangular beam section of width b mm and effective depth d mm. Take σcbc = 5 N/mm2, σst = 140 N/mm2, m = 18.66

To find Neutral Axis (NA)

σcbc /(σst/m) = xc/(d – xc)

5/(140/18.66) = xc/(d – xc)

Therefore, xc  = 0.399d mm= 0.4dmm

To find lever arm

z = d – xc/3

= d – 0.4d/3

= 0.867dmm

= 0.87d mm

To find Moment of resistance

Mr = C x z

= bxccbc/2)z

= b (0.4d)(5/2)(0.87d)

= 0.87 bd2 N-mm

To find the percentage of steel

Equating, C = T

bxccbc/2 = Ast. σst

Therefore, Ast = bxccbc/2 σst

 = [b (0.4d)(5/2)]/140

= bd/140 mm2

Pt = Ast. 100/bd

= (bd/140) x (100/bd)

= 0.71

3 thoughts on “Solved numerical examples | Design of Singly reinforced sections”

  1. Thanks Benjujk for your effort. Please provide sample of one complete multistoried building design using working stress method.

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