Take a look at the truss below:
Say the question wants you to find the force in member AE. If we use the method of joints, it will take forever to work through the whole truss!
An alternative method is to take a section that cuts through member AE as such:
Take a look at the truss below:
Say the question wants you to find the force in member AE. If we use the method of joints, it will take forever to work through the whole truss!
An alternative method is to take a section that cuts through member AE as such:
This way, we can consider the FBD of this cut truss and apply the equations of equilibrium to obtain the force in member AE directly. Shortcut for the win!
For the method of sections we would usually need to apply [ΣM = 0] in addition to [ΣF_{x} = 0] and [ΣF_{y} = 0] that the method of joints uses.
The same principle of determining tension/compression applies:
Let’s look at an example now.
This way, we can consider the FBD of this cut truss and apply the equations of equilibrium to obtain the force in member AE directly. Shortcut for the win!
For the method of sections we would usually need to apply [ΣM = 0] in addition to [ΣF_{x} = 0] and [ΣF_{y} = 0] that the method of joints uses.
The same principle of determining tension/compression applies:
Let’s look at an example now.