During seismic excitation RC elements in three- dimensional structures such as arch ribs and L shape bridge piers, torsional moments in addition to bending moments, shear and axial forces affect the member. Interaction curves among those three sectional forces to use in nonlinear time history analysis has not been clarified yet. In this paper 9 test models with different bending and torsional moments, pitch of hoop lateral tie are tested by newly developed loading machine. The test model has 400*400 mm cross section and 1600 mm length. The axial forces are 10% of target compressive strength of concrete, i.e. 4 MPa. Pitch of hoop lateral tie is 30mm or 60mm. Type of loading are pure bending, pure torsion and combined loading of moment and torsion. Load deformation relationship, strain of reinforcement, crack and strain of surface, distribution of curvature and unit angle of twist, energy absorption and equivalent damping ratios obtained by these loading test are shown in detail.
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