Questions and discussion for this lecture live here. Fire away by hitting Reply below 
@ 18:39 for Bending moment diagram , why we are ignoring ve and vf
Good question - the shear force is zero at F and because we’re taking moments about point E, the lever arm for any force that passes through that point would be zero so there is no associated moment.
S
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Is there a way to vizualize how a frame shears and bends by the values we get from these exercises?
Or it is more a “statical” graph, that shows values necessary to consider when we further detail the structure or try to dimension it?
With bending diagrams I always imagine a beam bending, but I have hard time vizualizing shear geometrical transformations…
@petrasvestartas - I’m not sure I fully understand your question - would you mind elaborating a little further?
Seán
At time 21.22 why is the bending moment diagram between F and E a concave instead of convex
When you plot a sheer force diagram, what an engineer sees?
I mean can you relate to actual deformations?
@tak24g - essentially, because the UDL is pointing upwards (we’re typically used to seeing UDLs point down). More fundamentally, we can get to this shape by looking at the shear force diagram the results form this UDL. We can directly infer the shape of the bending moment diagram from the shear force diagram - what we covered in lecture 22 is critical to understanding this…make sure to review that lecture.
S
Internal shear force, in isolation, doesn’t manifest as a clear visible deformation in the structure, at least in the same way that we think of bending moment leading to deflection.
In reality however - both shear and moment occur simultaneously so a more helpful way to think about it is that any outwardly visible beam deflection is a combined result of both bending and shear within the structure.
S
Thank you, it helps.
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