Flexural Behaviour of Concrete Beams Reinforced With GFRP Bars L. Ascione, G. Mancusi and S. Spadea Department of Civil Engineering, University of Salerno, Via Ponte don Melillo, 84084 – Fisciano (SA) Italy ABSTRACT: The paper presents some of the results from a large experimental program undertaken at the Department of Civil Engineering of Salerno University. The static behaviour under service conditions of concrete beams reinforced with GFRP (Glass Fibre-Reinforced Polymer) as well as CFRP (Carbon Fibre-Reinforced Polymer) bars and stirrups is examined. Within the whole experimental program concerning forty beams, two different concrete strengths and two different percentages of reinforcement are taken into consideration. The final aim is to investigate both deflections at midspan and crack widths. Moreover, the ultimate behaviour up to failure is also investigated. A part of this experimental program, concerning ten prototypes reinforced with GFRP bars, is here presented and discussed. Finally, comparisons with analytical predictions given by CNR- DT 203/2006 are also shown. KEY WORDS: CNR-DT 203/2006, crack width, deflection, GFRP bars. NOMENCLATURE b cross section width h cross section depth d effective dept (distance from internal tensile bars to the top of the section) L beam span L a shear span F single external force according to the four point bending scheme D eff effective diameter of FRP bar DN nominal diameter of FRP bar A 0 f amount of reinforcement (FRP) in compression A f amount of reinforcement (FRP) in tension E c compressive Young modulus of concrete (eval- uated according to [22]) E f tensile Young modulus of FRP bars f max tensile strength of FRP bars R cm cubic compressive strength of concrete (mean value) R ck cubic compressive strength of concrete (fractile 5%) f cfm tensile strength of concrete under flexure (mean value evaluated according to [22]) F cr cracking limit, referred to the external force F F u ultimate limit, referred to the external force F M cr bending moment at midspan corresponding to cracking limit M u bending moment at midspan span correspond- ing to ultimate limit I 1 moment of inertia of un-cracked cross section I 2 moment of inertia of the cracked cross section f deflection of members w k characteristic cracks width s rm average distance between cracks Introduction Over the last few years the use of FRP (Fibre-Rein- forced Polymer) bars as internal reinforcement for concrete structures has been sustained and particu- larly encouraged in the international technical and research community and specific technical instruc- tions and guidelines have been published. Japan has been one of the forerunners and drew up the first design guidelines in 1996, subsequently translated into English 1 year later [1]. Further guidelines were published in Canada in 1996 [2], followed by those published by ACI in 2000 and revised in 2006 [3]. More recently technical documents dealing with the designing and execution of FRP concrete construc- tions have been published in Europe [4] and in Italy [5]. Despite the numerous advantages exhibited by concrete structures reinforced with FRP bars, there are still many issues demanding further Ó 2010 Blackwell Publishing Ltd j Strain (2010) 46, 460–469 460 doi: 10.1111/j.1475-1305.2009.00662.x