Civil Engineering - Strength of Materials - Discussion

Discussion Forum : Strength of Materials - Section 1 (Q.No. 15)
15.
If the shear force along a section of a beam is zero, the bending moment at the section is
zero
maximum
minimum
average of maximum-minimum
none of these.
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
25 comments Page 1 of 3.

Muhammad ismail said:   4 years ago
If the shear force is zero along the section means a member is not subjected to any load. When a member is not subjected to any load then how BMD can be maximum?

Please explain it.

Waqar said:   5 years ago
Well said @Abdul Samad.

The right answer is either maximum or minimum.

Haroon Rashid said:   5 years ago
Since the question doesn't mention the type of beam, so the anology of zero sf and max bm can't be applied, as it varies depending on type of beam. The correct answer should be when sf is zero bm is constant.

Aswin said:   6 years ago
Well said, thanks @Abdul Samad.

Vishal said:   6 years ago
The answer is incorrect, just shear being zero is not sufficient to tell whether is it maximum or minimum.

We require a derivative of shear force to confirm whether is it max or min.
The correct answer will be E since it can be Max and Min both in this section.
(2)

Mhathung kikon said:   6 years ago
For concentrated load acting on a given section,
When sf=0, then BM= max,
For sf=0 along a section, it varies so BM will be either max or min.
(1)

Kumarpvk said:   7 years ago
S=dM/dx.

As s=0, BM=CONSTANT.
(1)

Abdul samad said:   7 years ago
If so, what is the value of bending moment in a cantilever beam loaded with udl?

Sf=0 at the free end.
Bm= 0 at free end.

The correct answer is, it can be maximum or minimum depending on the support condition.

Milan sorathiya said:   7 years ago
In simple language, according to me, if the shear force is zero then the bending moment is max or min.

Max means in positive direction (can be positive, negative, zero) and min. Means negative direction (can be negative, zero or positive, it depends on function).

Now, as per structural analysis, the term is maximum positive or maximum negative not a minimum.

Means mathematical minimal is a structural negative maximum.

Plan said:   7 years ago
If the question was "The positive or Negative BM, then the answer would have been maximum or minimum". But since the question is about the BM, if we draw a BM diagram of fixed end beam, there will be two maximum BM, one is -ve and the other is +ve. So, for both maximum values, the shear force should be zero.

So, the answer is maximum.


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