Civil Engineering - UPSC Civil Service Exam Questions - Discussion

17. 

A simply supported beam of span l and flexural rigidity EI, carries a unit point load at its centre. The strain energy in the beam due to bending is

[A].
[B].
[C].
[D].

Answer: Option C

Explanation:

No answer description available for this question.

Shashideep Kumar said: (Jul 22, 2017)  
Please give the explanation of the solution.

Soumik said: (Feb 14, 2018)  
I think option A is correct.

Yc=wl^3/48 EI for simply supported beam with point load on its centre.

Mohit Singh said: (Mar 15, 2018)  
since strain energy due external load = 0.5 x W x deflection.

And deflection for that beam you know.

Yasir Ashrafi said: (Aug 17, 2018)  
The correct Answer must be A.

Jerish David said: (Sep 3, 2018)  
Correct answer is option C only.

U= Integral(M^2*ds/2EI).
M= Wl/4,
Where, W = 1(unit load),
Substitute and integrate,
You get, U = (W^2*l^3)/(96EI),
U = l^3/96EI.

Musthafa said: (Sep 6, 2018)  
u=.5 * w * deflection.

w=1, put deflection will get option C.

Kripa said: (Sep 30, 2019)  
U = 0.5*P*(PL^3)/96EI.

P = Load (unit load here).

U = L^3/96EI.

Deepinder Singh said: (Jul 10, 2020)  
The formula is = integral (M^2 dx/2EI).

M= WL/4 (as we know point load is given at the centre then the maximum bending moment is wl/4).
W= 1 (Unit load assume this value).

Substitute and Integrate using the formula:

You will get = (W^2 X L^3)/(96 EI).
Therefore the answer is = (L^3)/96EI.

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