THE INFLUENCE OF STIFFNESS AND BOND OF FRP BARS AND TENDONS ON THE STRUCTURAL BEHAVIOUR OF REINFORCED CONCRETE MEMBERS

摘要

Reinforcements made of FRP material differ quite drastically from conventional reinforcements made of reinforcing steel and prestressed steel with respect to their bond properties and E moduli. In considering the load-bearing capacity and serviceability of FRP-reinforced elements, their mechanical properties must therefore be paid particular attention to. The object of this paper is to use results from the literature and own investigations to form a basis for discussion and analysis of the main parameters that influence the bond behaviour and the resultant development lengths. Special attention will be given to splitting during load application. And finally, the redistribution of stresses in mixed-reinforcement concrete members will be discussed on the basis of experimental results and theoretical investigations. It transpires that on account of the high achievable bond strength of FRP material in concrete and the in part low E modulus of the material, an increased risk of splitting arises. Furthermore, it was established that with mixed-reinforcement concrete members, the "softer" (in terms of bond and stiffness properties) reinforcement element only contributed negligibly to absorbing the load.