Analytical Behaviors of Steel and CFRP Reinforced Concrete Beams in Fire

Abstract

Abstract The study of thermal behaviors of concrete structures has been an area of great interest to researchers over a long period of time. This paper presents the details of analytical studies, which were carried out in order to investigate high temperature performance of steel or carbon fiber reinforced polymer (CFRP) bar reinforced concrete (RC) beams. This performance is considered to be highly dependent on elevated temperature properties of employed materials (i.e., concrete, steel, and FRP), concrete cracking model, and temperature related strain components. The effects of these parameters in relation to the experimental data were studied in order to establish those that are critical for the prediction of fire resistance of steel or FRP RC beams. Constitutive models for temperature dependent thermal expansion coefficient of concrete and steel have been proposed and validated against the recorded beam behaviors. The effects of transient creep strain were found insignificant in the studies presented in this paper. Non-orthogonal and orthogonal crack formations were found to be suitable for steel and CFRP reinforced beams, respectively. A highly non-linear rebar stress distribution was observed at the mid-span of the beam. Compressive stresses were produced in the steel bars, owing to their restrained thermal dilatation during heating.