Civil Engineering - UPSC Civil Service Exam Questions - Discussion

Discussion Forum : UPSC Civil Service Exam Questions - Section 1 (Q.No. 11)
11.
The plastic modulus of a section is 5 x 10-4m3. Its shape factor is 1.2 and the plastic moment capacity is 120 kNm. What is the value of the yield stress of the material ?
100 N/mm2
200 N/mm2
240 N/mm2
288 N/mm2
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
15 comments Page 1 of 2.

Mahender Singh Rawat said:   3 months ago
Section modulus Z = 5 * 10^-4 * 10 * 9 mm^3.
= 5 * 10^5 mm^3.

Moment capacity M = 120 * 10^3 * 10^3.
= 120 * 10^6.

Yield stress = M/Z.
= 120 * 10^6/5 * 10^5,
= 240 N/mm^2.

Jawad Ali said:   3 years ago
@Priya.

Mp = plastic moment capacity
Zp = plastic section modulus
Fy = yield stress
Mp = Zp * fy =>
fy = Mp/Zp= 120 * 10^3/5* 10^-4,
= 24 * 10^7 N m^-2,
= 240 N/ mm2.

Neeraj Thakur said:   5 years ago
Mp = Fy*Z.
Fy= yield stress=moment/section modulus,
Fy=120kNm/5*10^-4 cubic metere.
= 120*1000*1000/(5*10^-4*10^9)N/mm^2 (Converted cubic meter into 10^9 cubic mm)
= 240N/mm^2.

Naveen said:   6 years ago
zp = 4.8x10^4.
mp = 120.
shape factor = 1.2 = zp/ze.
ze = 4.8x10^4/1.2 = 4x10^-4 m3.

mp/my by equating 1.2 = 120/1.2 = 100 knm.
my = fy*ze = 100/4x10^4 = 25x10^4 = 250MPa.

Meharban Bharti said:   6 years ago
Shape factor = plastic moment /yield moment.
Shape factor = plastic modulus/elastic modulus.

1.2 = 120 * 1000000/yield moment.
From this yield moment = 100000000 Mmm.
From second equation.
1.2 = 5/10000/elastic section modulus.
From here , elastic modulus = (please convert all units in Nmm) = 1250000/3,
From moment equation:
Yield stress = moment/section modulus.
Yield stress = 100000000/(1250000/3) = 240N/mm2.

Rajat said:   7 years ago
Sf = Mp/My.
1.2 = 120*1000/My,
My = 10^5,
Now, Sf = fy*Zp/My.
fy = 240*10^6 N/m2,
fy = 240 N/mm2.

Priya said:   8 years ago
I can't understand Mp, Zp denoted here?

Sharath said:   9 years ago
Section modulus Z = 5 * 10^-4 * 10 * 9 mm^3.
= 5 * 10^5 mm^3.

Moment capacity M = 120 * 10^3 * 10^3.
= 120 * 10^6.

Yield stress = M/Z.
= 120 * 10^6/5 * 10^5,
= 240 N/mm^2.

Jignesh said:   9 years ago
Plastic Section Modulus = Zp = 5 * 10 m^3.
Shape factor k = Zp / S = 1.2.
So, S = elastic section modulus = Zp / k
= 4.17 * 10m^3.

Plastic Moment Capacity = Mp = 120 kN - m.
Fy = Yield strength of the material or Yield stress of the material.
Mp = Fy * Zp.

Fy = yield stress = 120 * 10^3/5 * 10
= 240 N / mm^2 as mm = 10^3m.

Abhay said:   10 years ago
Yield stress = Plastic moment capacity/Plastic modulus.

= Mp/Zp.

= 120*10^3/5*10 = 240 N/m^2.


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