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:
24 comments Page 1 of 3.

Jameel said:   2 years ago
I think the right answer is 38.22cm. So, here nearly is 38 cm.
(3)

Anshu Rana said:   3 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:   3 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.

Sumit Yadav said:   3 years ago
K = m.σ(cbc)/ m.σ(cbc) + σ(st) = 99.5.
J = 1-0.42k = 41.7 ~ 40.
(2)

Shubha chakrabortty said:   3 years ago
n(actual neutral axis) =k(design constant) *d, =0.4*460=184mm = 18.4cm.
Permissible working stress=1400 kg/cm2(mild steel),
Then, k = 0.4(madular ratio=18.67),
n/3 = 61.33.
Lever arm = 460 - 61.33(d-n/3),
= 398.67mm,
= 39.86cm
~40cm.

Krishan Gupta said:   3 years ago
The answer is 40cm because here in question the value of C=8 is wrong. M=18 is for M15 concrete and for M15 C=5.

Rajesh sahoo said:   4 years ago
Describe, how the answer is 38.23?

Mayur said:   4 years ago
What is the lever arm?
(1)

Anurag said:   5 years ago
Option C is the correct answer.

Krishankant singh said:   5 years ago
38.23 is the correct answer.


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