CFRP (Carbon Fiber Reinforced Plastics) rods have almost equal tensile strength and slightly higher relaxation compared with prestressing steel bars. Adding to the above, CFRP rods are corrosion free even in marine environment, therefore, they are very attractive to use as prestressing tendons of prestressed concrete members at ports and harbours. Also, posttensioning beams prestressed with CFRP rods by unbonded system are considered to be advantageous as members for superstructures of wharves.
　The purposes of this study are as follows:
(1) To evaluate the bending behavior of the unbonded prestressed concrete beams prestressed with CFRP rods. There are two kinds of unbonded beams, namely, one of them has joint, and the other has four joints (composed of 5 units).
(2) To assure the stability of effective prestress of these beams.
　In addition to be above, the authors proposed an improved method for the cross sectional analysis after cracking, including the calculation of the ultimate moments of the beams.