We have a beam with 1 internal hinge just like the picture. We know the internal hinge can not transfer moments between AB and BD. We know the 30 kN force makes some moments on BD & AB. If B (internal hinge) can not transfer moments between the two elements, then why does the 30 kN (which is applied on BD) cause moments in AB?
I don't know if i'm clear enough but the 30 kN force makes some moments on AB while we know that no moments can transfer between AB & BD.