Civil Engineering - RCC Structures Design - Discussion

Discussion Forum : RCC Structures Design - Section 3 (Q.No. 1)
1.
If permissible working stresses in steel and concrete are respectively 1400 kg/cm2 and 80 kg/cm2 and modular ratio is 18, in a beam reinforced in tension side and of width 30 cm and having effective depth 46 cm, the lever arms of the section, is
37 cm
38 cm
39 cm
40 cm
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
25 comments Page 3 of 3.

Sumit Yadav said:   4 years ago
K = m.σ(cbc)/ m.σ(cbc) + σ(st) = 99.5.
J = 1-0.42k = 41.7 ~ 40.
(2)

Anshu Rana said:   4 years ago
Ca/Xa = Ta/m/d-Xa,
80/Xa =1400/18/46 - Xa,
80/Xa = 77.7/46-Xa,
80(46-Xa) = 77.7Xa.
Xa= 23.33.
d-Xa/3.
46-23.33/3.
Lever arm = 38.23~40cm.

Anshu Rana said:   4 years ago
Ca/Xa = Ta/m/d-Xa,
80/Xa =1400/18/46 - Xa,
80/Xa = 77.7/46-Xa,
80(46-Xa) = 77.7Xa.
Xa= 23.33.
d-Xa/3.
46-23.33/3.
Lever arm = 38.23~40cm.

Jameel said:   3 years ago
I think the right answer is 38.22cm. So, here nearly is 38 cm.
(3)

Abdulmuiz Abdulkabir said:   6 months ago
Lever arm (z) = d-nd/3.
n= m.~c/ m.~c + ~St,
n = 18(80)/18(80)+1400.
n = 0.5.

Therefore Z = 46- (0.5×46)/3,
Z = 46 - 7.666,
= 38.333.


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