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Review
. 2024 Dec 25;17(1):13.
doi: 10.3390/polym17010013.

Strengthening Reinforced Concrete Members Using FRP-Evaluating Fire Performance, Challenges, and Future Research Directions: A State-of-the-Art Review

Mahmood Haris  1 , Ergang Xiong  1 , Wanyang Gao  2 , Mabor Achol Samuel  1 , Najam Us Sahar  1 , Anwar Saleem  1
Affiliations
Review

Strengthening Reinforced Concrete Members Using FRP-Evaluating Fire Performance, Challenges, and Future Research Directions: A State-of-the-Art Review

Mahmood Haris et al. Polymers (Basel). .

Abstract

Fiber-reinforced polymer (FRP) composites are increasingly used in civil engineering for strengthening and repairing existing reinforced concrete (RC) members using externally bonded reinforcement (EBR) and near-surface mounted (NSM) methods. However, the fire performance of FRP-strengthened RC members has been an important issue that should be properly considered in the fire safety design process since FRP composites exhibit significant performance degradation at elevated temperatures. This paper aims to review studies on the fire performance of FRP-strengthened RC members based on the existing research results presented in the literature to provide a comprehensive understanding of key factors influencing the structural behavior of FRP-strengthened RC members under fire conditions. It provides an overview of FRP composite material properties, such as their mechanical and thermal behavior and bond characteristics between FRP-to-concrete interfaces at elevated temperatures. Additionally, this paper reviews experimental and numerical research conducted on FRP-strengthened RC members, examining load-carrying capacities and fire endurance ratings. Finally, this review will provide existing fire resistance design methods as well as simple design methods for temperature prediction.

Keywords: RC members; elevated temperature; fiber-reinforced polymers (FRPs) composites; finite element modeling; fire resistance; strengthening.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

Figure 1
Figure 1
Normalized elastic modulus of FRP materials (i.e., bars, plates, sheets) at elevated temperatures. (a) Bars; (b) Plates; (c) Sheets (Refs. [9,11,12,18,27,28,30,31,33]).
Figure 1
Figure 1
Normalized elastic modulus of FRP materials (i.e., bars, plates, sheets) at elevated temperatures. (a) Bars; (b) Plates; (c) Sheets (Refs. [9,11,12,18,27,28,30,31,33]).
Figure 2
Figure 2
Normalized tensile strengths of FRP materials (i.e., bars, plates, sheets) at elevated temperatures. (a) Bars; (b) Plates; (c) Sheets (Refs. [2,8,9,10,11,12,18,27,28,29,30,31,32,33]).
Figure 2
Figure 2
Normalized tensile strengths of FRP materials (i.e., bars, plates, sheets) at elevated temperatures. (a) Bars; (b) Plates; (c) Sheets (Refs. [2,8,9,10,11,12,18,27,28,29,30,31,32,33]).
Figure 3
Figure 3
FRP Composites Thermal Properties [37].
Figure 4
Figure 4
Failure modes (obtained from Correia et al. [47]). (a) Anchorage slippage; (b) Epoxy adhesive failure at elevated temperature.
Figure 5
Figure 5
Summary of test results from the bonded joint tests at elevated temperatures. (a) Normalized bond strengths vs. adhesives temperatures; (b) Normalized interfacial fracture energy vs. temperatures (Refs. [39,40,41,42,46,48,51,54]).
Figure 6
Figure 6
Summary of the test results of normalized bond strengths vs. adhesives temperatures (Refs. [46,65,66,68,69]).
Figure 7
Figure 7
Comparisons of measured temperature responses of insulation, FRP, and FRP-to-concrete interfaces as a function of fire exposure time (Refs. [74,75,76,77]).
Figure 8
Figure 8
Some common failure categories of FRP-strengthened beams [97]. (a) Tensile rupture of FRP after steel yielding; (b) Concrete compression crushing; (c) Concrete cover delamination; (d) Debonding between FRP-to-concrete interface; (e) Shear failure; (f) Intermediate crack (IC) debonding.
Figure 9
Figure 9
Temperature responses of beams A and B (determined by Adelzadeh [102]).
Figure 10
Figure 10
Debonding failure between FRP-to-concrete interface (obtained from Gao et al. [86]).
Figure 11
Figure 11
Diagram of thermocouples and fire insulation schemes (obtained from Dong et al. [87]).
Figure 12
Figure 12
Measured deflection at midspan responses as a function of fire duration [87].
Figure 13
Figure 13
Axial deformations of columns as a function of fire duration (Refs. [115,116,117,118]).
Figure 14
Figure 14
FE model predictions of insulated CFRP-strengthened RC beams of Gao et al. [86]. (a) mid-height temperature; (b) bottom surface temperature; (c) midspan deflection.
Figure 15
Figure 15
Comparisons of measured and predicted load-deflection responses at ambient temperature (Refs. [138,143]).
See this image and copyright information in PMC

References

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