Concrete strength variation effect on numerical thermal deformations of frp bars-reinforced concrete beams in hot regions

Abstract

The steel corrosion phenomenon could reduce the durability and the serviceability of concrete structures reinforced with steel bars. Moreover, the repair cost of these structures is very expensive. Consequently, it seems necessary to substitute steel bars by fiber reinforced polymer (FRP) bars, in concrete structures, because of their high properties, particularly, their excellent corrosion resistance and high tensile strength-to-weight ratio. Nevertheless, the use of FRP bars in concrete structures, built in hot regions, may cause splitting cracks within concrete at the interface of FRP bars-concrete, and eventually the failure of the concrete cover. This paper presents a nonlinear finite element investigation using ADINA software to analyze the effect of concrete strength variations on thermal deformation distributions in the concrete cover surrounding glass FRP (GFRP) bars for reinforced concrete beams under high temperatures up to 70 °C. The main results show that the concrete strength variation has no big influence on the transverse thermal deformation of FRP bars-reinforced concrete beams for thermal loads less than the cracking thermal load ΔTcr, producing the first radial cracks in concrete at the FRP bar-concrete interface, varied from 20 to 35 °C depending on the ratio of concrete cover thickness to FRP bar diameter (c/db) and the compressive concrete strength f'c varied from 1 to 3.2 and 25 to 90 MPa, respectively. However, for thermal loads greater than ΔTcr, the transverse thermal deformations decrease with the increase in the concrete strength. Comparisons between analytical and numerical results in terms of thermal deformations are presented.