Forces on a Bridge Truss

Forces on a Bridge Truss

by Christy Rodgers

​Forces on a Truss

Calculate Force​

• ​The idea behind a truss is that we want the truss to remain static.

• That is, we do not want our truss to move.

• Therefore, when a force is acting on our truss, we want to counterbalance it with another force in the equal and opposite direction.

Multiple Choice

_________ Forces are forces acting along the same line. For a truss to remain static the sum of the forces acting on it must be zero.

• Static 

• Linear

• Vertical

• Perpendicular

Multiple Choice

If the block has a force of 10 N being exerted on it to the left, what should the magnitude of Force A be to keep the block static?

• 5

• 0

• 10

• 15

Multiple Choice

If the block has one force of 10 N acting to the left, and one force of 6 N acting to the right, what must force A be to keep the block static?

• 4

• 14

• 0

• 10

Multiple Choice

What additional force A is needed to keep the block in static equilibrium?

• 30N pointing Right

• 30N pointing Left

• 15N pointing right

• 35N pointing up

Multiple Choice

What additional force A is needed to keep the block in static equilibrium?

• 10N Pointing right

• 10N Pointing left

• 18N Pointing left

• 6N Poinitng Left

Multiple Choice

To determine F1 and F2, we will use our equations for adding linear forces. In this case the forces are vertical.

What is F₁ ______

• 25

• 50

• 100

• 15

Multiple Choice

Determine the external forces acting on the truss.

• F1 = 75 N, F2 = 25 N

• F1 = 50 N, F2 = 25 N

• F1 = 50 N, F2 = 50 N

• F1 = 25 N, F2 = 50 N

​STRESS and YIELD STRENGTH

​The key to good engineering design is to analyze your truss and recognize which members are likely to fail first and then modify the design.

To do this, it is important to understand stress and yield strength.

Multiple Choice

The truss will ______ when the stress on a web member is greater than the material's yield strength.

• Fail

• Yield

• get stronger

Multiple Choice

Stress is a measure of the amount of _______ exerted per unit area of a surface.

• strength

• force

• weight