#### Guide to design of Singly reinforced Sections | Civil Engineering

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

- Basic definitions and formulas
- Understanding stresses and modular ratios
- Assumptions for singly reinforced sections
- Design procedure for Singly reinforced section – I
- Solved Numericals for Singly reinforced beam | Method I
- Design of Singly reinforced sections | Design Method 2
- Solved Numericals for Singly reinforced beam | Method 2
- Moment of Resistance for Singly reinforced sections
- Solved numerical example | Moment of resistance
- Solved numerical example 2 | Guide to singly reinforced sections

**Now we will move on with our next solved example in which we will make use of formulas derived earlier. That is why it is necessary that you go through the entire step by step guide in order to gain complete understanding.**

#### Numerical Problem

**Calculate the moment of resistance of an RC beam 250mm wide, the depth of the centre of reinforcement being 500mm. Assume σcbc = 5N/mm2, σst = 140 N/mm2, modular ratio = 18.66**

#### Given that,

b = width of the beam = 250mm

d = depth of the beam = 500mm

σ_{cbc} = permissible compressive stress in concrete in bending = 5N/mm^{2}

σ_{st} = permissible stress in steel = 140 N/mm^{2}

m = modular ratio = 18.66

#### To find Neutral Axis (NA)

σ_{cbc}/(σ_{st}/m) = x_{c}/(d – x_{c})

5/(140/18.66) = x_{c}/(500 – x_{c})

X_{c} = 199.95mm = 200mm

#### To find lever arm

z = d – x_{c}/3

= 500 – 200/3

= 433.33mm

#### To find Moment of resistance

M_{r}= C x z

= bx_{c}(σ_{cbc}/2)z

= 250 x 200 x 5/2 x 433.33

= 54166250 N-mm

= 54.166 kN-m

OR

M_{r}= T x z

= A_{st}. σ_{st}.z —————————equation 1

#### To find A_{st}

Equating, C = T

bx_{c}.σ_{cbc}/2 = A_{st}. σ_{st }

Therefore, A_{st}= bx_{c}.σ_{cbc}/2 σ_{st}

A_{st} = (250 x 200 x 5/2)/140

A_{st }= 892.85 mm2

**Substituting the value of A _{st} in equation 1;**

M_{r}= T x z

= A_{st}. σ_{st}.z

= 892.85 x 140 x 433.33

= 54165817 N-mm

= 54.1658 kN-m

**From the above example, it is clear that in case of a balanced section, the Mr can be calculated either as Mr = C x z or as Mr = T x z. The values obtained for moment of resistance are the same for both the formulas. **

kindly advise a structural design of 65 feet x 80 feet godown with RCC column and 4.5 in thick roof for black cotton soil. it case a no columns in the hall

case b with one row of column in the hall.

Hello Mr Kumar,

Are you yet to design your godown? If yes, please let me know and we could have a discussion on it.

FROM THIS PROBLEM I HAVE GAIN A CLEAR CONCEPTION ABOUT RCC SINGLY REINFORCED BEAM DESIGN AND IT IS HELP FULL FOR DIPLOMA CIVIL ENGINEERING STUDENTS AND RCC DESIGNERS ALSO.

THANK YOU VERY MUCH