EXPERIMENTAL STUDY ON THE FLEXURAL BEHAVIOR OF CONCRETE BEAMS PRESTRESSED WITH AFRP TENDONS

A group of simple beams prestressed with AFRP tendons or steel strand have been tested.The effect of several factors,such as the reinforcement ratios of AFRP tendon and steel rebar,the prestressing force,etc,on the load-carrying capacity of the beams is investigated.And the cracking load,the ultimate load,the load-deflection relationship,the crack development,the plane-section assumption,and the strain developments of AFRP tendon and steel reinforcement are discussed.The results demonstrate: the whole mechanical process of the concrete beam prestressed with AFRP tendons can be idealized to the trilinear relationship.The first stage is from loading to cracking,the second to yield of the tension steel,and the third to the ultimate load-carrying capacity.Although the AFRP tendon material has no the yielding plateau,the beams prestressed with AFRP tendons show clear deformation signs before collapsing because of the low elastic modulus of the AFRP material.When the beams collapse,the AFRP tendon will not always reach the ultimate strain value and its strain can be calculated with the plane-section assumption.In addition,the ultimate load-carrying capacity of the beams can be improved by increasing the prestressing force.