Lesson 4 & 5: Shear and Moment Diagrams

Question 1

What is a shear force (V)?

Answer 1

The internal force parallel to the cross-section of a beam.

Question 2

What is a bending moment (M)?

Answer 2

The internal moment that causes bending in a beam.

Question 3

How do you construct a shear force diagram (V-line)?

Answer 3

1. Start from the left and move to the right.
2. Downward forces move the shear diagram downward.
3. Upward forces move the shear diagram upward.

Question 4

How do you construct a bending moment diagram (M-line)?

Answer 4

1. Start from the left and move to the right.
2. Clockwise moments move the M-line downward.
3. Counterclockwise moments move the M-line upward.

Question 5

What is the relationship between the shear force and bending moment diagrams?

Answer 5

• The slope of the moment diagram at any point equals the shear force at that point.
• The change in moment between two points equals the area under the shear diagram.