Questions and discussion for this lecture live here. Fire away by hitting Reply below 
When you draw shear force diagram you did not consider hinge 4.5 KN? Is it becausw the two parta cancel each other?
Good question - remember that this is a rotational hinge so it allows the transmission of force (not moment). This means that it has no impact on the shear force diagram and for the purposes of drawing the shear force diagram, it may as well not exist.
Seán
1 Like
Hello Sean, i guess it is almost same question but with different perspective maybe not sure : Technically speaking, we can almost say that these LHS of the rotational hinge and RHS of the rotational hinge are different “sub-structures” (not structures because it is still one system, but they are actually only bonded by the rotational hinge) which means that as @petrasvestartas noted these forces are cancelling out in the global manner, but if we separeted these sub structures through the hinge of course we would expose these Vf forces and these Vf forces would make the shear force at the hinge equals to 0 (from LHS) and then again 4.5 to upwards (Vf from RHS) while drawing the overall SFD for the whole structure. Is it the correct interpretation ?
Thanks a lot,
Burak