Glass fibre composite reinforcement bars have been used in the reinforced concrete structures as a powerful solution of the steel corrosion problem. This research work aims to use a 3D finite element method and EURO – code models to simulate a concrete beam reinforced with fibre composite bars under the effects of high temperature. The behaviour of the structure is very complex due to load combination and different material response. The applied load was an external mechanical load and a thermal load. The material response was considered as thermal expansion, cracking, crushing, yielding and changing of material properties with the temperature increase. The FE element was modified to allow temperature distribution and material properties changing to throw thickness of the concrete beam. In addition, the geometrical non – linearity is considered in the analysis due to the large deflection of the structure. The prediction results were compared with the available experimental results, and it gives a well correspond.