Abstract : The present research is devoted to study the behavior of RPC beams subjected to pure torsion, the torsional toughness of RPC beams, and proposed analytical model to estimate the torsional moment of RPC beams. The experimental work of this research which includes examined ten RPC beams includes both solid and hollow beams in torsion, the main variables in this research are focused on the influence of the hollow RPC beams which includes (shape, location, and dimension) and effect of the transverse