If you have a laser-sharp eye, you would have noticed that in all the previous questions, we could only calculate our displacement Δ or slope θ at the point where the load is applied.
What if we wanted to find Δ or θ away from the point of load application? Or what if we have more than one load acting on the structure? How do we find our Δ or θ in such scenarios?
We can no longer use the method defined in Chapter 6.2. But fear not! We have another method, called virtual work.
Basically, this method works by applying a “virtual load” on the point where we want to find our Δ or θ. This “virtual load” will result in “virtual work” done on the structure, which we can then equate to our internal strain energy to find Δ or θ:
If you have a laser-sharp eye, you would have noticed that in all the previous questions, we could only calculate our displacement Δ or slope θ at the point where the load is applied.
What if we wanted to find Δ or θ away from the point of load application? Or what if we have more than one load acting on the structure? How do we find our Δ or θ in such scenarios?
We can no longer use the method defined in Chapter 6.2. But fear not! We have another method, called virtual work.
Basically, this method works by applying a “virtual load” on the point where we want to find our Δ or θ. This “virtual load” will result in “virtual work” done on the structure, which we can then equate to our internal strain energy to find Δ or θ:
Because the load applied is “virtual”, then surely our internal strain energy U_{i} is different as well! And so we have a slightly different method to calculate our strain energy:
Let’s look at an example now to see how virtual work "works" (pun intended).
Because the load applied is “virtual”, then surely our internal strain energy U_i is different as well! And so we have a slightly different method to calculate our strain energy:
Let’s look at an example now to see how virtual work "works" (pun intended).