Civil Engineering - UPSC Civil Service Exam Questions - Discussion


The plastic section modulus of a rectangular section of width 100 mm and depth 12 mm is

[A]. 1000 mm3
[B]. 1800 mm3
[C]. 2400 mm3
[D]. 3600 mm3

Answer: Option D


No answer description available for this question.

Barqat Sheikh said: (Feb 25, 2015)  
Plastic section modulus = b*h^2/4.

= 3600 mm^3.

Hemanth Kumar said: (Nov 16, 2016)  
Z = bd^2/6 = 2400mm^3.

Kanu said: (Apr 7, 2017)  
Here the section is rectangular.

Z= (bd^2)/4 is right
If in case there is a circular section then section modulus will be;
Z = (bd^2)/6.

Deepak Dalal And Ritu Dalal said: (Apr 28, 2017)  
Section modulus = moment of inertia of the area / maximum distance of any point from the axis.
Moment of inertia for rectangular section = bh^3/12.
Maximum distance of any point from the axis = h/2.
So, section modulus for rectangular section = bh^2/6.

And the correct answer from above from is 2400.

Naveen Kallan said: (Sep 14, 2017)  
Shape factor= 1.5 for rectangular section
S.F = Zp/Ze
Ze = bd^2/6
Zp = 3600 mm^3.

Aatif said: (Jan 15, 2018)  
Answer should be 2400. Section modulus for rect section- bd^2/6.

Darshan said: (Jan 18, 2018)  
Plastic modulus and elastic modulus are different.
shape factor comes into picture here;
so 2400 *1.5 = 3600.
shape factor is 1.5 for rectangular section.

Subha Annadurai said: (Mar 12, 2018)  
How to find plastic section modules & elastic section modules for rectangle?

Subha Annadurai said: (Mar 12, 2018)  
For rectangle,
Plastic section modules = bd^2/4,
Elastic section modules = bd^2/6,
Shape factor = 1.5.

Ravi Rajput said: (Oct 10, 2018)  
How to calculate plastic section modulus? Please explain.

Anil Kumar said: (Nov 24, 2019)  
(Zp=Ac x yc+At x yt).
Ac = area of compression zone.
At = area of tension zone.
Yc &yt are the C.G of the both zones.

So the answer is zp = 600x300+600x300.

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