Truss Systems and Types of Forces on Structures

Truss Systems and Types of Forces on Structures

by Christy Rodgers

Types of Forces​

​To know the strength of a member, it is necessary to understand how the internal forces of the web members are determined and how this will affect the overall design of the truss.

There are four different types of forces that truss members can be exposed to: tension, compression, shear, and torsion.

Multiple Choice

If a truss member is exposed to too much internal force, the member will break or fail.

• True

• False

• Depends on the Force

• What is a truss?

​It is important to know the type of force that is being applied to the material. With most materials, there is a difference in strength for each force type.

Multiple Choice

When a member is being pulled apart, it is called _____________

• Tension

• Compression

• Torsion

• Shear

Multiple Choice

When a member is being twisted.

• Tension

• Compression

• Torsion

• Shear

Multiple Choice

When a member is exposed to forces cross-ways.

• Tension

• Compression

• Torsion

• Shear

Multiple Choice

When a member is being pushed together or crushed.

• Tension

• Compression

• Torsion

• Shear

​Study the Chart

​It is a comparison of Balsa Wood and Bass Wood

Fill in the Blank

After studying  the previous slide, which wood is stronger, Balsa or Basswood?

Multiple Choice

An ________ distributes load among its members. If you analyze the type of load on each member, you will find that each member in an arch is under compression load.

• Arch

• Beam

• Triagle

• Square

Multiple Choice

One of the most useful structural forms is the __________ When a load is applied to it, the upper members are in compression and the lower member is in tension.

• Arch

• Triangle

• Square

• Beam

Multiple Choice

If a truss is statically determinate (stable), it means the truss has the proper combination of joints and web members.

• True

• False

Multiple Choice

If the truss has too many web members, it is considered to be statically indeterminate

• True

• False

Multiple Choice

If the truss has too many joints, it is considered to be unstable

• True

• False

Fill in the Blank

How many Joints does this truss have?

Fill in the Blank

How many web members does this truss have?

Fill in the Blank

Using the formula, 2J __M+3, What operand should be used if you have 7 joints and 11 members?

Multiple Choice

This bridge has _____joints and ____Members.

• 6, 12

• 5, 20

• 8, 14

• 8, 16

Multiple Choice

If a bridge has 8 joints and 11 web members, use the table to determine if it is statically determinate, statically indeterminate or unstable.

• Statically Determinate

• Statically Indeterminate

• Unstable