When I give a modifier for 0.01 to beams it means its is providing zero stiffness against torsion then these forces are transferred to which members?. Moreover in practical structures how torsion could be avoided in beams ( reinforcement detailing could do that .. ?) . Furthermore when a stiffness modifier of 0.35 is given to beams the same beams fails and needs a bigger section. So all this could not conclude that assigning zero stiffness against torsion in beams means that no torsional forces will occur in real structure.