Civil Engineering - RCC Structures Design - Discussion

Discussion Forum : RCC Structures Design - Section 5 (Q.No. 20)
20.
A singly reinforced concrete beam of 25 cm width and 70 cm effective depth is provided with 18.75 cm2 steel. If the modular ratio (m) is 15, the depth of the neutral axis, is
20 cm
25 cm
30 cm
35 cm
40 cm
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
6 comments Page 1 of 1.

Vasikh Ali said:   4 years ago
Moment of compression area wrt neutral axis = moment of equivalent tensile area wrt NA.

Gsasikumar said:   6 years ago
Thanks for solving this sum.

Hussein said:   6 years ago
Take the moment about N.A axis equal to zero.

0.5 * b n^2 = m Ast (d-n).
0.5 25*n^2 = 15 * 18.75 (70-n).
12.5*n^2 = 19425-281.25n.
n = 30 cm.

Heiro said:   6 years ago
I don't get the answer. Please explain me.

Pawan said:   6 years ago
Thanks @Anbarasan Muthaiah.

Anbarasan muthaiah said:   1 decade ago
0.5*b n^2 = m Ast (d-n).
0.5 25*n^2 = 15 *18.75 (70-n).
12.5*n^2 = 19425-281.25n.

By solving n = 30cm.
(2)

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