FRP bars are made of innovative materials, and use of these bars in residential and commercial buildings and infrastructure could result in their increased applications. This requires establishment of fire resistance of the FRP bar RC. This paper describes the results of a parametric study that was carried out on hybrid and carbon FRP bar RC beams. The influence of concrete strength and load ratio on the high temperature performance of beams was investigated. The study used finite element modelling and was conducted with the help of numerical models that were calibrated previously by the authors against the data of experimentally tested beams. It was found that the beam strength and stiffness reduce in the same proportion between two consecutive load ratios and are nearly uninfluenced by the concrete strength. The amount of load was found to be a critical factor for the beam thermal resistance. Preliminary guidance for FRP RC beam design in fire situation is provided on the basis of findings of the study. Copyright © 2013 John Wiley & Sons, Ltd.