John
U-Bolt will not restraint any moments ?
Im not sure, you sure ?
A simple example :
A Pipe 1000 mm length outside diameter 30 mm
Node 10 to 20 DX =1000mm
At location X = 500 mm (Node 15) is a U-Bolt welded at one plate (structur).
And now give at node 10 a Z-Force.
Is in this example no restraint moment Y at node 15 ?
That to mean this pipe rotate without reaction free ? Never John.