Fiber reinforced polymer prestressed tension elements as reinforcement for concrete

The use of FRP for reinforcing is not as popular as its use for prestressing because the modulus of elasticity to strength ratio of most FRP bars is relatively small compared to steel, and the unit price is significantly higher than steel. Therefore, to control deflection and crack width under service conditions, FRP reinforced sections often need to be greatly over-reinforced, which increases the overall cost of the structure. This paper offers an innovative solution to the latter problem by suggesting the use of tension elements as reinforcement. The CFRP tension elements developed in the present investigation are concentrically pretensioned prisms of small cross-section. Such elements would reduce the need for high reinforcement ratio while simultaneously endowing the member with greater flexural rigidity. This paper will briefly explain the concept of FRP prestressed tension elements used for reinforcement of concrete beams, followed by the description of an experimental investigation related to the development of CFRP tension elements and their use as flexural reinforcement in concrete beams. The effectiveness of the tension elements in controlling crack width and deflections under service loads is demonstrated.