# Structural Analysis Questions and Answers – Shear and Moment Diagrams for a Beam

This set of Structural Analysis Multiple Choice Questions & Answers (MCQs) focuses on “Shear and Moment Diagrams for a Beam”.

Following sign convention for force direction is followed:-

For moments, clockwise is considered –ve.

1. In case of a beam, resistance to normal force is considered to be more important than resistance to bending and shear force.
State whether the above statement is true or false.
a) True
b) False

Explanation: Resistance to bending and shear force is given more importance than resistance to normal force in most cases involving beams.

2. What is the exceptional case when resistance to normal force is considered to be more important than resistance to bending and shear force in beams?
a) Expansive axial force
b) Compressive axial force
c) Bending moment at both ends
d) Bending moment at one end

Explanation: In these cases, buckling effects have to be nullified.

Following figure is used in Q3-Q8.
In the following figure, all supports are roller type and B and D are hinges. All the options are given in KN and KN/M wherever applicable.
BMD and SFD starts from point A.
AB = BC = CD = DE = EF = FG = 2m

3. What will be the starting value of SFD?
a) 10
b) -10
c) 5
d) -5

Explanation: Support reaction at point A is 10KN in downward direction.
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4. What will be the shape of SFD in the entire beam?
a) Straight line
b) Straight line with point of discontinuities
c) Curve
d) Curve with point of discontinuities

Explanation: Since load is not a function of x, so SFD will always be straight line. But, since load varies suddenly at some points, SFD will have discontinuities.

5. How many points of discontinuities will be there in the SFD?
a) 1
b) 2
c) 3
d) 4

Explanation: 3 discreet loads are applied in between the beam (excluding starting and end points). So, 3 discontinuities will be there.

6. What will be the starting value of BMD?
a) 20
b) -20
c) 5
d) -5

Explanation: Bending moment at point A is +20KN/M. So, curve will start with +20.

7. What will be the shape of BMD in the entire beam?
a) Straight line
b) Straight line with point of discontinuities
c) Curve
d) Straight line with varying slope

Explanation: Since, SFD is always parallel to the x axis (as load is always discreet) BMD will always be a straight line. Since, there is an absence of discreet external moment in between the beam, there won’t be any discontinuities in the graph. But, slopes will vary as SFD has discontinuities.

8. How many times would slope of BMD change?
a) 1
b) 2
c) 3
d) 4

Explanation: There are 3 points of discontinuities in SFD. So, slope will also change at those three points.

Following figure is used in Q9-Q14
In the following figure AB=BC=CD=2m, and DE=EF=1m.
A is a fixed support while C and F are of roller type. B and D are hinges.
All the options are given in KN and KN/M wherever applicable.
BMD and SFD starts from point A.

9. What will be the starting value of SFD?
a) 25
b) -25
c) 15
d) -15

Explanation: Support reaction at point A comes out to be 25KN in upward direction upon solving as shown in earlier questions.

10. What will be the shape of SFD in the entire beam?
a) Straight line
b) Straight line with points of discontinuities
c) Curve
d) Straight line with points of discontinuities parallel to x axis

Explanation: On integrating load SFD comes out to be straight line. It will have points of discontinuities too as discreet loads are there in between. But, SFD won’t be always be parallel to x axis as continuous load is applied.

11. How many points of discontinuities will be there in the SFD?
a) 1
b) 2
c) 3
d) 4

Explanation: 2 discreet loads are applied in between the beam (excluding starting and end points). So, 3 discontinuities will be there.

12. What will be the starting value of BMD?
a) 20
b) -20
c) 10
d) -10

Explanation: Bending moment at point A is -10KN/M. So, curve will start with -10.

13. What will be the shape of BMD in the entire beam?
a) Straight line
b) Straight line with point of discontinuities
c) Curve
d) Combination of curve and straight line

Explanation: A combination of discreet and continuous load will lead to such BMD.

14. How many times would slope of BMD change?
a) 1
b) 2
c) 3
d) infinite

Explanation: Since a part of BMD is curve, it will change its slope continuously.

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