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
Discussion:
25 comments Page 1 of 3.
Niranjan goenka said:
9 years ago
We know, mσcbc/σst =n/d - n [we get, m=18, σcbc = 80kg/cm2, σst=1400kg/cm2, d=46 cm]
or n = 23.32cm [putting this value].
We know, lever arm = d - n/3.
= 46 - 23.32/3.
= 38.22 cm.
I think the correct answer will be 39 cm.
or n = 23.32cm [putting this value].
We know, lever arm = d - n/3.
= 46 - 23.32/3.
= 38.22 cm.
I think the correct answer will be 39 cm.
Shubha chakrabortty said:
4 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.
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.
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.
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.
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.
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.
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.
Krishan Gupta said:
5 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.
Sumit Yadav said:
4 years ago
K = m.σ(cbc)/ m.σ(cbc) + σ(st) = 99.5.
J = 1-0.42k = 41.7 ~ 40.
J = 1-0.42k = 41.7 ~ 40.
(2)
Jameel said:
3 years ago
I think the right answer is 38.22cm. So, here nearly is 38 cm.
(3)
K.K.Shah said:
7 years ago
x = (m.cb.d )/cb+st.
x = 18.
z = D- x/3.
z = 40.
x = 18.
z = D- x/3.
z = 40.
Alka gautam said:
7 years ago
38.23 is the right answer. I too got the same.
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