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
Discussion:
25 comments Page 1 of 3.
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.
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.
So, the answer is maximum.
Nikhil said:
1 decade ago
Where the shear force becomes zero. The B.M becomes maximum.
Proof:
The b.m for simply supported beam subjected to point load at middle.
The shear force at A.is W/2.
We know that the shear force becomes zero at L/2 of the span.
The B.M is maximum at L/2 the shear force becomes zero.
Therefore,
(W/2)*(L/2)=WL/4.
Proof:
The b.m for simply supported beam subjected to point load at middle.
The shear force at A.is W/2.
We know that the shear force becomes zero at L/2 of the span.
The B.M is maximum at L/2 the shear force becomes zero.
Therefore,
(W/2)*(L/2)=WL/4.
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.
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)
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.
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.
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.
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.
Please explain it.
Hemant saini said:
8 years ago
In magnitude numerical value will be maximum.
But when we consider negative sign so that it can be maximum or minimum.
Because dM/dX=0 so, M can be max or min.
But when we consider negative sign so that it can be maximum or minimum.
Because dM/dX=0 so, M can be max or min.
Muniraj jodli said:
8 years ago
Like cantilever, and subjected to bending moment at the free end then there is no shear force (s.f.d is a straight line), and b.m.d is rectangular.
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.
When sf=0, then BM= max,
For sf=0 along a section, it varies so BM will be either max or min.
(1)
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