Abstract. Concrete is a heterogeneous composite material made up of cement, sand, coarse aggregate and water mixed in a desired proportion to obtain the required strength. Plain concrete does not with stand tension as compared to compression. In order to compensate this drawback steel reinforcement are provided in concrete. Now a day, for improving the properties of concrete and also to take up tension combination of steel and glass fibrereinforced polymer (GFRP) bars promises favourable strength, serviceability, and durability. To verify its promise and support design concrete structures with hybrid type of reinforcement, this study have investigated the load-deflection behaviour of concrete beams reinforced with hybrid GFRP and steel bars by using ATENA software. Fourteen beams, including six control beams reinforced with only steel or only GFRP bars, were analysed. The ratio and the ordinate of GFRP to steel were the main parameters investigated. The behaviour of these beams was investigated via the load-deflection characteristics, cracking behaviour and mode of failure. Hybrid GFRP-Steel reinforced concrete beam showed the improvement in both ultimate capacity and deflection concomitant to the steel reinforced concrete beam. On the other hand, finite element (FE) modelling which is ATENA were validated with previous experiment and promising the good result to be used for further analyses and development in the field of present study. IntroductionFibre reinforced polymer (FRP) composites were first developed during the 1940's for the military and aerospace applications [1]. The characteristics of FRP include high resistance to corrosion, lightweight, high strength-to-weight ratio, high tensile and impact strength, fatigue resistance, nonconductive and magnetically neutral [2]. As a result, FRP have been successfully used in many construction applications such as chemical and waste-water treatment plant, underwater structures, bridges, substation reactor bases, airport runways, laboratories and water tanks [3]. The other application is to strengthen the structurally deficient beams or columns with FRP sheets or plates [4]. Today, applications of FRP in the building industry have realized the increasing popularity in Malaysia. As proven, many construction projects are using FRP water tank to replace the conventional water tank that facing steel corrosion problems. In fact, cost of manufacturing these products is quite high compared to the conventional materials. Hybrid composite beam (HCB) is a structural member, utilizing several different building materials with dissimilar attributes. Furthermore, the hybrid composite beam is a sustainable technology that combines the strength and stiffness of conventional concrete and steel. In this report, we investigated