Parametric finite element analysis of FRP reinforced concrete beams in fire and design guidelines

Abstract

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.

Fire Performance of FRP-RC Flexural Members: A Numerical Study

“…Apart from the fire tests, some numerical or finite element (FE) models are also proposed in the literature to predict the fire performance of FRP-RC flexural members [14,[47][48][49][50][51]. The numerical and test results provided in the existing literature have promoted a good understanding of the thermal and structural responses of FRP-RC flexural members under fire exposure [51,52].…”

Load ratio effects on the structural fire behaviour of glass fibre‐reinforced polymer‐reinforced concrete beams with mid‐span bar lap splices – Experimental study

“…Thus, the bond strength of GFRP bars with concrete is the most vulnerable characteristic in fire conditions and could be the main reason for the failure of GFRP‐reinforced concrete structural members when subjected to elevated temperatures in case of fire. This is one of the main causes leading to hindering broader utilization of fibre‐reinforced polymer (FRP) bars as reinforcement in concrete structures 1,3–5 …”

“…Another important aspect of the design of GFRP‐reinforced concrete beams is the serviceability requirements greatly affected by the load level applied, especially in fire conditions 3 . The higher the applied load level is, the more significant deflections and more subsequent cracks can be developed in a concrete beam.…”

“…The higher the applied load level is, the more significant deflections and more subsequent cracks can be developed in a concrete beam. With more cracks formed on the exposed surfaces of a concrete beam, more heat can penetrate the beam cross‐section and thus, leads to an increase in the temperatures of the reinforcing bars 3,11 . In a relatively recent study conducted by Ryu et al, 12 the effects of the applied load ratio on the behaviour of conventionally steel‐reinforced concrete beams exposed to standard fire were experimentally studied.…”

“…However, they are known for their poor thermal resistance and consequent loss of bond with concrete at a temperature above the glass transition temperature of the polymer matrix used in their composition. The glass transition temperature of GFRP is relatively low as it lies between 93 and 120 C. 3 Thus, the bond strength of GFRP bars with concrete is the most vulnerable characteristic in fire conditions and could be the main reason for the failure of GFRP-reinforced concrete structural members when subjected to elevated temperatures in case of fire. This is one of the main causes leading to hindering broader utilization of fibre-reinforced polymer (FRP) bars as reinforcement in concrete structures.…”