For a torque to be generated, a lever arm is required. If the latter is zero, the torque will also be zero.
Okay, if I interpret it correctly, I gain nothing by placing the truss at point A?
The new value for E gave a few millimeters, so if it isn't directly wrong, I would of course prefer that, even though I agree that it feels good not to be on the edge.
I can change L by drawing a smaller opening, but before I do that, I wonder if L should be center-to-center between the columns or if it is the distance between the "inner sides" of the columns? If I measure between the inner sides, then L becomes 4.23 m, which further reduces the deflection to 11.7 mm and L/360.
Does this sound correct?
The new value for E gave a few millimeters, so if it isn't directly wrong, I would of course prefer that, even though I agree that it feels good not to be on the edge.
I can change L by drawing a smaller opening, but before I do that, I wonder if L should be center-to-center between the columns or if it is the distance between the "inner sides" of the columns? If I measure between the inner sides, then L becomes 4.23 m, which further reduces the deflection to 11.7 mm and L/360.
Does this sound correct?
Yes.
A big thank you for all the help in the thread! It has been very educational!
I hope questions about this will come up in other threads so I can pass the information on
I hope questions about this will come up in other threads so I can pass the information on
About a year later, I can add that the reason you don't get the correct deflection is that you have considered the beam as simply supported when it is not the case. Claiming that the reaction forces have "zero lever arm" is incorrect because the lever arm between support "3" and support "2" must be used to calculate the applied moment. The point loads between 1 and 2 will try to lift the beam at the end (point 3), and from the roof truss, we have a point load that resists and partially counteracts the deflection.
Calculate the moment resulting from the "cantilever" between 3 and 2.
Point load = half a roof truss (half the load on the roof truss at the end)
times lever arm =
M=1.2*P/2
Calculate the deflection that this applied moment causes on a simply supported beam.
v=L/6EI * -M * L/2 (1 - ((L/2)^2) / L^2)
And subtract this deflection from the deflection you calculated on your simply supported beam to get closer to the truth. It is also possible to replace the distributed load with point loads, but I don't think it will significantly affect the result.
Calculate the moment resulting from the "cantilever" between 3 and 2.
Point load = half a roof truss (half the load on the roof truss at the end)
times lever arm =
M=1.2*P/2
Calculate the deflection that this applied moment causes on a simply supported beam.
v=L/6EI * -M * L/2 (1 - ((L/2)^2) / L^2)
And subtract this deflection from the deflection you calculated on your simply supported beam to get closer to the truth. It is also possible to replace the distributed load with point loads, but I don't think it will significantly affect the result.
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