The fire performance of GFRP-RC beams based on FE thermal analysis

The fire performance of GFRP-RC beams based on FE thermal analysis | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article The fire performance of GFRP-RC beams based on FE thermal analysis Fabricio Longhi Bolina, Débora Bretas Silva, Eduardo Cesar Pachla This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5000212/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 26 Oct, 2024 Read the published version in Journal of Building Pathology and Rehabilitation → Version 1 posted 9 You are reading this latest preprint version Abstract GFRP (glass fiber reinforced polymers) rebars can be used in RC (reinforced concrete) structures as an alternative to conventional steel rebars. Their application offers advantages, especially in chemically aggressive environments, as they can reduce the C (concrete cover) thickness required and also optimize the cross-sectional dimensions of these structures as well as their durability and service life. However, based on FE (finite element) numerical analysis solved by Abaqus software, this research has shown that the reduction in C-thickness promotes a notorious incongruity: an improvement in the fire sensitivity of these structures. The time in which GFRP-RC structures failed in fire can be around 400% lower in relation to identical conventional steel RC structures. In some cases, the fire resistance rate (FRR) of GFRP RC structures can be less than 10 min when the critical temperature of these rebars (around 100°C) is taken into account. The interest in structural durability criteria is not sufficient to justify the application of this new type of reinforcement in some concrete buildings. GFRP Glass Fiber rebars Glass Fiber Reinforcements Glass Fiber Reinforced Concrete Structures in fire Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 1 INTRODUCTION The service life of concrete structures has become increasingly important in recent years. The use of steel-reinforced concrete in areas with high chloride concentrations (e.g., coastal areas, seawater and de-icing salts) or chemical and radioactive wastes (e.g., in industrial facilities) can lead to corrosion of the steel rebars [ 1 ], resulting in concrete spalling [ 2 ] and weakening structural integrity [ 3 ], reducing the service life and structural performance [ 4 ]. Durability requirements must be considered in any structural design. When predicting service life, it is usually conservatively assumed that the service life ends when corrosion begins [ 5 ], which is typically solved in design by incorporating a minimum concrete cover thickness to protect the steel reinforcements [ 6 ], [ 7 ]. An alternative to solving the durability requirement is to use fiber reinforced polymer (FRP) rebars in place of the traditional steel [ 8 ]. The material is corrosion-resistant [ 9 ]. In addition, these composite materials are not only lighter than steel, but they also have higher tensile strength, electromagnetic transparency and low maintenance requirements [ 10 ]. FRP rebars enable thinner structural cross-sections with high reinforcement density by reducing the thickness of the concrete cover. Studies have demonstrated the application of FRP rebars in bridge decks [ 11 ], structural walls [ 12 ], industrial [ 13 ], maritime [ 14 ] and also infrastructure constructions [ 15 ] and others. Glass FRP (GFRP) is the most commonly used for concrete because it is less expensive and has acceptable mechanical properties for use in concrete structures [ 15 ], [ 16 ]. GFRP reinforcement is a composite material and are an attractive alternative to steel rebars to ensure long-term structural performance [ 16 ]. A low weight and high strength compared to conventional steel is an interesting advantage of this solution [ 17 ]. A high corrosion resistance, high strength-to-weight ratio, high stiffness-to-weight ratio, high degree of chemical inertia, excellent fatigue tolerance is another advantage to use the GFRP rebars (GFRP-R) [ 18 ]. The sustainability is a point of interest, measured by its associated economic and environmental impacts throughout its life cycle [ 16 ]. However, the benefits of GFRP-R instead of classical steel reinforcement are not exploited due to their vulnerability at high temperatures and under fire [ 14 ]. Mechanical properties of GFRP materials degrade significantly in this environment, leading to a serious and significant reduction in bearing capacity and brittle failure of GFRP-RC structures [ 19 ], mainly due to the tensile strength and elastic modulus damage [ 8 ]. Fire is one of the most serious potential risks for buildings and structures, and for this reason international codes provide specific guidelines to take account this scenario in the design of structures [ 18 ]. GFRP-R are more vulnerable to high temperatures than steel rebars [ 18 ], [ 20 ], [ 21 ], highlighting an issue to be addressed. The fire sensitivity of GFRP-R limits their wide use in construction. As seen in the steel reinforcements, the physical and mechanical properties of GFRP decrease at high temperatures. Material degradation is the key phenomenon, but it must meet the requirements of the relevant fire codes to be used as a structural solution. Most of these refer to the time available in a fire before the structural failure [ 22 ]. Extensive studies are available on the high temperature behavior of concrete reinforced with steel rebars, and their fire behavior is well known and also prescribed by many standardized procedures [ 23 ], [ 24 ], [ 25 ]. However, there is a gap in the literature regarding the analysis of concrete structures reinforced with GFRP-R subjected to fire. In the case of Brazil [ 23 ], as well as in the European standard [ 24 ], there are no proposed design procedures for the fire design of these structures. Due to the lack of knowledge, design guidelines (conservatively) do not recommend yet the use of GFRP rebars in structures where the fire action has to be considered at design (i.e., in buildings) [ 26 ]. There are many philosophies on the design of concrete structures in fire. The most usual is to limit the reinforcement to reach a critical temperature. This method is well accepted due to the low thermal diffusivity of concrete and makes the reinforcement the critical component of the structure. In the case of the steel rebars, this temperature is in order of 500°C, as proposed by fib Bulettin No.38 [ 27 ]. At critical temperature steel loses around half of its original strength, and the structure can no longer support the loads during a fire. An adequate fire design for reinforced concrete could be achieved by providing minimum dimensions and sufficient concrete cover thickness to protect the reinforcement [ 28 ]. Standards as CSA S806 [ 29 ] continue to use the temperature in the GFRP-R as a critical criterion to design the GFRP-RC structures, clearly based on the philosophy established to traditional RC structures. The reduction in strength with increasing temperature varies considerably depending on the type of fiber and resin [ 30 ]. The tensile strength is significantly more affected by elevated temperature than the elastic modulus, but some authors highlight that the fire performance of these rebars is unclear [ 19 ]. Wang et al. [ 31 ] suggested a critical temperature based on 50% strength loss is 325°C. As the ultimate temperature, Abbasi and Hogg [ 32 ] proposed 462°C, while the experimental research done by Nigro et al. [ 33 ] highlight 460°C. Hajiloo et al. [ 13 ], Bilotta et al. [ 18 ], and Jin et al. [ 19 ] stablished 400°C as the ultimate temperature, but Rosa et al. [ 30 ] suggests 300°C to structural design (where the 50% of the ultimate condition is reached). Around 700°C there is a full decomposition of the resin [ 30 ]. However, the bond of the GFRP-R to concrete are damaged at 100°C, and this temperature need to be assumed as critical. Researches such as Katz et al. [ 34 ] concluded that the bond performance at ambient temperature, as well as the bond strength and stiffness degradation with temperature, depend mostly on parameters associated with the surface properties of the rebars. According to the authors, at 200°C the GFRP bond strength are reduced at least 80%, while in the steel rebars are only 38%. The literature about the reduction with temperature of the bond properties of GFRP-R to concrete is still very limited [ 8 ]. There are authors who believe that when continuous reinforcement from side to side of the RC element was used, not significant slips occurred at the end anchorage zones, and then the structural integrity was guaranteed [ 18 ]. Glass fibers can resist 800°C [ 35 ], but they do not perform their job perfectly in concrete elements without binding material (resin). In fact, according to Rosa et al. [ 14 ], the effects of elevated temperatures on the bond between GFRP rebars and concrete are more severe than the mechanical loss of these rebars. Studies have already shown that when the glass transition temperature of the polymeric matrix is reached (approx. 100°C), the bond strength between GFRP-RC decreases by 90 % [ 8 ], [ 36 ], [ 37 ]. Thee results raise concerns about the performance of GFRP-RC structures exposed to fire, as most of the bond strength of the reinforcements is likely to be lost in the early stages of a fire while temperatures are still moderate [ 14 ]. Studies show that GFRP-RC structures exposed to fire fail prematurely because the bond is lost along the overlapping length of the rebars [ 22 ]. The aim of the proposed study was to understand the fire behavior of GFRP-RC structures. A thermal analysis of a group of rectangular beam cross-sections was proposed. A group of RC beams with different width and concrete cover was assumed. The average temperature of the concrete and reinforcement was considered. The uniqueness of the proposed research is to compare a series of RC beams with different widths and heights and variable concrete cover thicknesses to determine and correlate the fire behavior and the FRR of GFRP and conventional steel reinforcements when exposed to fire. 2 METHODS 2.1 Research overview The study attempts to better understand the fire behavior of GFRP-RC structures and their correlation with steel RC structures. A thermal analysis of several rectangular beam cross-sections was presented. Abaqus software was used to solve a set of finite elements (FE) models. A variety of RC beam widths and heights and concrete cover thicknesses were assumed. The average temperature of the concrete and reinforcement (assuming conventional steel and GFRP) was identified as a crucial criterion. A comparison was done. 2.2 Cross-sectional thermal analyses The concrete cover (C) thickness criterion considered in structural fire design ( \(\:{\text{C}}_{\text{f}}\) ) is not the same as the durability and service life requirements. The \(\:{\text{C}}_{\text{f}}\) is measured from the edge of the beam to the center of longitudinal reinforcement, as shown in Fig. 1. It’s a standardized criterion. The section width (W) and height (H) were assumed as variables for the study. The thickness of the slab ( \(\:{\text{t}}_{\text{s}}\) ) was 100 mm in all cases. The cross-section shown in Fig. 1a establishes the results to define the sagging bending resistant moment (+) of the RC beams (the concrete temperature above the neutral axis and the positive steel reinforcements as used in the conventional design procedure). The same in Fig. 1b, but to the hogging moment (-). The temperature time history in concrete (average between pt1 to pt5 control points) and reinforcement (average between Rb1 to Rb3 control points) temperatures was monitored to determine the thermal field of each selected cross section (Table 1 ). For the concrete temperatures, since the concrete cross-section at the bearing capacity of the beam is above (in case of sagging moment) or below (hogging moment) the neutral axis, only measurement points in this region were assumed (i.e., 0.5 x H). The concrete temperature is the average of the control points pt1(+) to pt5(+) (in case of the sagging moment) and pt1(-) to pt5(-) (hogging moment). The beam cross-sections considered in the study are shown in Table 1 . The usual width and height of the beams (as is usual in engineering practice) were taken into account. Table 1 – Beams assumed in the research Cross-section characteristics and nomenclatures Beam number Nomenclature Width W (mm) Height H (mm) \(\:{\text{C}}_{\text{f}}\) thickness (mm) 1 B1w15h50 150 500 20 to 50 2 B2w20h50 200 500 20 to 50 3 B3w25h50 250 500 20 to 50 4 B4w30h50 300 500 20 to 50 5 B5w35h50 350 500 20 to 50 6 B6w20h60 200 600 20 to 50 7 B7w20h70 200 700 20 to 50 8 B8w20h80 200 800 20 to 50 9 B9w20h90 200 900 20 to 50 10 B10w20h100 200 1000 20 to 50 As shown in Table 1 , beams B1 to B5 were designed to investigate the effect of beam width on the average temperature of longitudinal reinforcements and concrete, while keeping the beam height fixed at 500 mm. Beams B6 to B10, on the other hand, fixed the beam width at 200 mm keeping the beam height as variable. 2.3 Numerical procedures Conduction is the primary heat transfer process, while convection and radiation are the mechanisms for heat transfer from the environment to the structural surfaces exposed to fire [ 38 ]. Eq. 1 shows that the thermal diffusivity is related to the mass loss \(\:\rho\:\) , the thermal conductivity \(\:\lambda\:\) and specific heat \(\:{C}_{p}\) . In the case of concrete, these parameters are those proposed in EN 1992 − 1.2 [ 24 ]. In the case of reinforcement, the thermal parameters are not required in the model, as described in section 2.4 . $$\:{\alpha\:}=\frac{{\lambda\:}}{{\rho\:}.{\text{C}}_{\text{p}}}$$ 1 The governing equation for the convective and radiative heat transfer analysis are defined in Eq. 2 [ 38 ], where \(\:{\text{n}}_{\text{y}}\) and \(\:{\text{n}}_{\text{z}}\) are the components of the vector outward normal to the cross-sectional surface; \(\:{\text{h}}_{\text{r}\text{a}\text{d}}\) and \(\:{\text{h}}_{\text{c}\text{o}\text{n}}\) are the radiative and convective heat transfer coefficient, respectively; T is the initial temperature (20°C) and \(\:{\text{T}}_{\text{E}}\) is the temperature of the environment (assumed as ISO 834 [ 39 ] according to the EN 1992 − 1.2 [ 24 ] design procedure). The radiation heat transfer coefficient is given by Eq. 3 , where \(\:{\sigma\:}\) is the Stefan-Boltzmann constant (σ = 5.67 x 10 − 8 W/m². \(\:{^\circ\:\text{C}}^{4}\) ), and \(\:{\epsilon\:}\) the emissivity factor (0.70 according to EN 1992 − 1.2 [ 24 ]). The convective heat transfer 25 and 9 W/m²°C in the fire-exposed and unexposed surface. $$\:\text{k}\bullet\:\left(\frac{\text{d}\text{T}}{\text{d}\text{y}}\bullet\:{\text{n}}_{\text{y}}+\frac{\text{d}\text{T}}{\text{d}\text{z}}\bullet\:{\text{n}}_{\text{z}}\right)=-\left({\text{h}}_{\text{r}\text{a}\text{d}}+{\text{h}}_{\text{c}\text{o}\text{n}}\right)\bullet\:\left(\text{T}-{\text{T}}_{\text{E}}\right)$$ 2 $$\:{\text{h}}_{\text{r}\text{a}\text{d}}=4\bullet\:{\sigma\:}\bullet\:{\epsilon\:}\bullet\:\left({\text{T}}^{2}+{\text{T}}_{\text{E}}^{2}\right)\bullet\:\left(\text{T}+{\text{T}}_{\text{E}}\right)$$ 3 Heating was applied to both lateral surfaces and one lower surface of the beam, as shown in Fig. 2 . The 3D model using thermal transient non-linear analysis is used to solved the problem. The concrete was modeled as DC3D8 finite element with classical integration from the ABAQUS library. A mesh analysis was performed and the mesh is rather refined, the size of the elements is approximately 1.0 x 1.0 x 1.0 mm. The time increment used was 0.001s and a convergence criterion of 0.1ºC. The DC3D8 assumes a single degree of freedom (temperature) at each node along the x, y, and z axis. The solution used to solve the thermal problem is shown in Eq. 4 , where the coefficients follow the same criteria and descriptions detailed in Eq. 1 to 3 , where “t” is the time. The temperature distribution in the cross-section is obtained through conduction thermal analysis, and the heat transfer equation is formulated by applying the principle of conservation of the energy to a three-dimensional differential control volume. $$\:\frac{\partial\:}{\partial\:\text{x}}\left({\lambda\:}\frac{\partial\:{\theta\:}}{\partial\:\text{x}}\right)+\frac{\partial\:}{\partial\:\text{y}}\left({\lambda\:}\frac{\partial\:{\theta\:}}{\partial\:\text{y}}\right)+\frac{\partial\:}{\partial\:\text{z}}\left({\lambda\:}\frac{\partial\:{\theta\:}}{\partial\:\text{z}}\right)={\rho\:}\bullet\:{\text{C}}_{\text{p}}\bullet\:\frac{\partial\:{\theta\:}}{\partial\:\text{t}}$$ 4 Where \(\:\frac{\partial\:{\theta\:}}{\partial\:\text{x}}\) , \(\:\frac{\partial\:{\theta\:}}{\partial\:\text{y}}\) and \(\:\frac{\partial\:{\theta\:}}{\partial\:\text{z}}\) is the temperature \(\:{\theta\:}\) gradient in the x, y and z-directions, and the \(\:{\rho\:}\bullet\:{\text{C}}_{\text{p}}\bullet\:\frac{\partial\:{\theta\:}}{\partial\:\text{t}}\) is the time rate of change of the thermal energy of the medium per unit volume. In the case of the thermal boundary conditions, the exchange of convection and radiation during the heating process was considered. 2.4 Reinforcements assumptions No reinforcement was used in the cross-section as its area is much smaller than that of concrete. The study focuses on the average temperature of the concrete cross-section and defines the reinforcement temperature assuming the concrete temperature in the same layer where the reinforcement is placed. Previous numerical FE studies by the authors, confirmed by full-scale experimental results (see [ 40 ], [ 41 ]), have already shown that the lack of reinforcement in the thermal model has little effect on the thermal field in the cross-section. The small cross-sectional area of the reinforcements compared to the total area of the concrete and the high thermal conductivity of the steel may contribute to the explanation. 2.5 Validation of the FEA model and numerical procedure The FE model proposed in this research and the numerical procedure to solve the heat transfer problem (mesh size, steps, boundary conditions, integration process, governing equations, etc.) were validated by the authors through an extensive full-scale test (heating according to ISO 834 [ 39 ]) which they carried out in various studies. Some of these can be found in research papers such as [ 41 ], [ 42 ], [ 43 ]. The FEA model and numerical simulation were also based on the approaches highlighted by the authors in [ 44 ]. 3 RESULTS AND DISCUSSIONS The temperature history in the concrete and in the positive and negative reinforcement is shown above. The temperature field in the cross-section and the fire resistance rate (FRR) of each beam, which are listed in Table 1 , are also shown. 3.1 Concrete The temperature history in the concrete is shown in Fig. 3. The temperature above (Fig. 3a) and below (Fig. 3b) the neutral axis is described. The temperature refers to the average of the points pt1 to pt5 (see Fig. 1). The critical temperature of the concrete (approx. 350°C) is also highlighted in the curves. The temperature above and below the neutral axis is elementary for the determination of the sag or hogging moment, if the usual analytical expressions for determining the bending capacity of these structures are taking into account. The average temperature in the cross-section of the beams naturally depends on their geometry. The most important factor influencing the average temperature of the concrete (above or below the neutral axis) is the width of the beam. Above the neutral axis analysis: at the end of the numerical analysis, the temperature difference between B1 and B5 is about 300°C, as shown in Fig. 3a. Assuming the height of the beam, the difference between B6 and B10 is no more than 50°C. Only B1, B2 and B6 to B10 reached the temperature that characterizes critical mechanical damage of the concrete, i.e., only the beams with 15 and 20 cm width. Beams with a width of more than 20 cm did not reach the critical temperature of the concrete. Below the neutral axis analysis: it is most affected by the high temperatures, as the three sides of this area of the beam are exposed to fire (see Fig. 2 ). As described in Fig. 3a, Fig. 3b also shows that the width of the beam has less influence on the temperature field in the cross-section than the height. At the end of the analysis, the difference between B1 and B5 (with a width of 15 and 35 cm respectively) is almost 400°C, while between B6 and B9 (with a height of 60 and 90 cm respectively) is no more than 50°C. It is also important to note that the critical temperature of the concrete is reached in all cases. B1 is the most critical condition, while B5 is the most stable in the fire. With regard to the concrete temperature, the width of the beams is decisive for their fire behavior. The critical temperature of the concrete must be discussed in parallel with the reinforcement to predict the structural fire behavior. The positive and negative reinforcement temperatures are discussed below. 3.2 Positive reinforcements Figures 4a, 4b, 4c and 4d show the temperature history in the reinforcements with C = 20, 30, 40 and 50 mm. The critical temperature of steel and GFRP reinforcements is also highlighted. The temperature history in the positive reinforcements is required to define and apply the analytical expressions for determining the sagging bending resistance moment in fire. The average temperature of the reinforcement is directly dependent on the thickness of the concrete cover. In general, the temperature of the reinforcement decreases in the order of 100°C to each 10 mm increase in concrete cover. Since the critical temperature of conventional steel reinforcement is five times higher than that of GFRP reinforcement, the FRR of these beams naturally tends to be higher. Assuming that C = 10, 20 or 30 mm, the GFRP beams do not reach 20 min to standard fire, while the beams with conventional steel rebars reach about 40, 60 and 70 min, respectively. The FRR of the conventional steel RC beam is at least 80 min and can reach a maximum of 110 min, depending on the beam width. At 50 mm, the FRR of the GFRP RC beam is approximately 30 min. It is important to note that in the most critical condition, the FRR of steel RC beams can exceed 80 minutes compared to GFRP RC structures. This condition highlights the safety of conventional steel RC structures in terms of fire performance and also the shortcomings that need to be discussed in order to apply GFRP reinforcement in conventional multi-storey buildings when fire safety requirements need to be met 3.3 Negative reinforcements The temperature in negative reinforcements with C = 20, 30, 40 and 50 mm is shown in Figs. 5a, 5b, 5c and 5d respectively. These rebars are more thermally protected compared to the positive rebars due to the adjacent slab. These temperatures are necessary to define and apply the analytical expressions required to determine the hogging bending resistance moment in case of fire. Figure 5 shows that high temperatures have no effect on steel reinforcement. This indicates that with the proposed cross-sectional dimensions of the beams (as given in Table 1 ), these reinforcements don't shown mechanical damage when the beam is exposed to fire. In contrast, the GFRP reinforcements with C = 20, 30, 40 and 50 mm reached their critical temperature at 90, 85, 80 and 75 min of fire exposure respectively. It's important to remember that the thickness C is counted for the surface of the beam. As the C thickness increases, the rebars are exposed to higher temperatures, which reduces their FRR tine. 3.4 Temperature field in the cross-section Figures 6 and 7 show the temperature field in cross-section for two cases of beams when B5w35h50 and B7w20h70 are described, respectively. These isotherms confirm the results shown in the previous sections of the study and also illustrate the heterogeneity of the temperature distribution in the cross-section. When increasing exposure time to the ISO 834 temperature, the thermal field and thus the average temperature in the concrete and in the reinforcement also improves. These temperatures cause mechanical damage to the materials (i.e., concrete and steel or GFRP reinforcements), which can lead to failure of the beam and any RC structure. 3.5 Ultimate condition in fire Figure 8 shows the FRR for each beam proposed in Table 1 when the critical concrete temperature (350°C) is reached. The concrete above and below the neutral axis, which is required to define the sagging and the hogging bending resistant moment in case of fire with the analytical expressions, respectively, has been considered. As expected, the compressive concrete below the neutral axis, which is required to determine the hogging moment, is most damaged by the fire. The concrete below the neutral axis develops a lower average temperature, which is partly due to the adjacent slab in this area. Comparing Fig. 8 with Figs. 9 and 10 , it is clear that the temperature of the reinforcement is crucial to justify the failure of the beams exposed to fire. Figure 9 and Fig. 10 show the FRR time assuming the critical temperature in the positive and negative reinforcement for conventional steel and GFRP rebars, respectively. Regarding negative reinforcement, the beams with conventional steel rebars have an FRR > 180 min. This time is not exactly determined because the numerical analysis ends at 180 min (as standardized building requirements often do not require FRR more than 180 min, which justify the authors criteria). Assuming the positive reinforcement temperatures shown in Fig. 9 , which represents the critical case of the fire-exposed beams, the FRR of the conventional steel RC beams was 401.1, 419.5, 375.0, and 348.4% higher than that of the identical GFRP RC beams at C = 20, 30, 40, and 50 mm. It is to be expected that the GFRP-RC beams will fail quickly in fire, which shows a major inconsistency in the technical application of these rebars. Of course, there is great interest in these reinforcements due to the aggressiveness of the environment (especially the chemical environment), but since the building must also meet a variety of performance requirements, the use of these rebars must be reconsidered in some cases. 4 CONCLUSIONS The main conclusions of this research were: The width is the main factor influencing the average temperature of the concrete in the cross-section of the beam; GFRP RC beams with a concrete cover thickness of 20, 30 and 40 mm do not reach the 20 min of the ISO 834 fire. It is to be expected that these beams will fail very quickly when subjected to high temperatures; In terms of fire resistance time, concrete beams with conventional steel reinforcement may have a fire performance - in some cases - four times higher than identical reinforced concrete structures with GFRP rebars; Taking into account typical cross-sectional dimensions of the RC beams, the negative GFRP reinforcement was damaged by the fire, while identical beams with steel reinforcement were not damaged; The study shows a contradiction: the lower concrete cover thickness of GFRP rebars compared to traditional steel rebars is advantageous in terms of environmental aggressiveness, but undesirable in terms of fire safety criteria. The susceptibility of GRP rebars to fire may help to explain this; In certain circumstances, the use of GFRP RC structures instead of the usual steel RC structures must be investigated and discussed, especially if the building has to meet fire safety requirements; As future research, the authors suggest considering the fire sensitivity of these reinforcements and finding a technical solution to improve the thermal and mechanical properties of the GFRP rebars at high temperatures. Declarations Author Contribution FLB: conceptualization, data curation, formal analysis, numerical analysis, writing original text; DBS: conceptualization, formal analysis; ECP: conceptualization, formal analysis. References Pillai RG et al (2019) Service life and life cycle assessment of reinforced concrete systems with limestone calcined clay cement (LC3). Cem Concr Res 118:111–119. https://doi.org/10.1016/j.cemconres.2018.11.019 Bilcik J, Holly I (2013) Effect of Reinforcement Corrosion on Bond Behaviour. Procedia Eng 65:248–253. https://doi.org/10.1016/j.proeng.2013.09.038 Ramanathan S, Benzecry V, Suraneni P, Nanni A (2021) Condition assessment of concrete and glass fiber reinforced polymer (GFRP) rebar after 18 years of service life. Case Stud Constr Mater 14:e00494. https://doi.org/10.1016/j.cscm.2021.e00494 Abbas H, Abadel A, Almusallam T, Al-Salloum Y (2022) Experimental and analytical study of flexural performance of concrete beams reinforced with hybrid of GFRP and steel rebars. Eng Fail Anal 138:106397. https://doi.org/10.1016/j.engfailanal.2022.106397 Safehian M, Ramezanianpour AA (2013) Assessment of service life models for determination of chloride penetration into silica fume concrete in the severe marine environmental condition. Constr Build Mater 48:287–294. https://doi.org/10.1016/j.conbuildmat.2013.07.006 NBR 6118 (2023) Design of reinfoced concrete structures - procedures (in Portuguese). Brazilian Natl Stand Organ EN 1992 – 1 (2004) 1, Eurocode 2: Design of concrete structures - Part 1–1: General rules and rules for buildings. Eur Comm Stand Rosa IC, Firmo JP, Correia JR, Barros JAO (2019) Bond behaviour of sand coated GFRP bars to concrete at elevated temperature – Definition of bond vs. slip relations. Compos B Eng 160:329–340. https://doi.org/10.1016/j.compositesb.2018.10.020 Benmokrane B, Ali AH, Mohamed HM, ElSafty A, Manalo A (2017) Laboratory assessment and durability performance of vinyl-ester, polyester, and epoxy glass-FRP bars for concrete structures. Compos B Eng 114:163–174. https://doi.org/10.1016/j.compositesb.2017.02.002 Bank LC (2006) Composite for construction - structural design with FRP materials. Wiley, New Jersey Correia JR, Bai Y, Keller T (2015) A review of the fire behaviour of pultruded GFRP structural profiles for civil engineering applications. Compos Struct 127:267–287. https://doi.org/10.1016/j.compstruct.2015.03.006 Kim GB, Pilakoutas K, Waldron P (2008) Thin FRP/GFRC structural elements. Cem Concr Compos 30(2):122–137. https://doi.org/10.1016/j.cemconcomp.2007.04.011 Hajiloo H, Green MF, Gales J (2018) Mechanical properties of GFRP reinforcing bars at high temperatures. Constr Build Mater 162:142–154. https://doi.org/10.1016/j.conbuildmat.2017.12.025 Rosa IC, Firmo JP, Correia JR, Mazzuca P (2021) Influence of elevated temperatures on the bond behaviour of ribbed GFRP bars in concrete. Cem Concr Compos 122:104119. https://doi.org/10.1016/j.cemconcomp.2021.104119 Ilg P, Hoehne C, Guenther E (2016) High-performance materials in infrastructure: a review of applied life cycle costing and its drivers – the case of fiber-reinforced composites. J Clean Prod 112:926–945. https://doi.org/10.1016/j.jclepro.2015.07.051 Younis A, Ebead U, Judd S (2018) Life cycle cost analysis of structural concrete using seawater, recycled concrete aggregate, and GFRP reinforcement. Constr Build Mater 175:152–160. https://doi.org/10.1016/j.conbuildmat.2018.04.183 Cadenazzi T, Dotelli G, Rossini M, Nolan S, Nanni A (2020) Cost and environmental analyses of reinforcement alternatives for a concrete bridge, Structure and Infrastructure Engineering , vol. 16, no. 4, pp. 787–802, Apr. 10.1080/15732479.2019.1662066 Bilotta A, Compagnone A, Esposito L, Nigro E (2020) Structural behaviour of FRP reinforced concrete slabs in fire. Eng Struct 221:111058. https://doi.org/10.1016/j.engstruct.2020.111058 Jin L, Liu Y, Zhang R, Du X (2024) Out-of-plane impact behavior and post-impact damage evaluation of GFRP bar-reinforced concrete shear walls in fire. J Building Eng 94:109942. https://doi.org/10.1016/j.jobe.2024.109942 Jafarzadeh H, Nematzadeh M (2022) Flexural strengthening of fire-damaged GFRP-reinforced concrete beams using CFRP sheet: Experimental and analytical study. Compos Struct 288:115378. https://doi.org/10.1016/j.compstruct.2022.115378 Thongchom C et al (2023) Experimental and Numerical Investigation of Steel- and GFRP-Reinforced Concrete Beams Subject to Fire Exposure. Buildings 13(3). 10.3390/buildings13030609 Carvelli V, Pisani MA, Poggi C (2013) High temperature effects on concrete members reinforced with GFRP rebars. Compos B Eng 54:125–132. https://doi.org/10.1016/j.compositesb.2013.05.013 NBR 15200 (2024) Design of reinforced concrete structures in case of fire (in Portuguese). Brazilian Natl Stand Organ EN 1992 – 1.2 (2004) Eurocode 2: Design of concrete structures - Part 1–2: General rules - Structural fire design. Eur Comm Stand ACI 318 (2014) Building Code Requirements for Structural Concrete. Am Concrete Inst (ACI) Nigro E, Cefarelli G, Bilotta A, Manfredi G, Cosenza E (2014) Guidelines for flexural resistance of FRP reinforced concrete slabs and beams in fire. Compos B Eng 58:103–112. https://doi.org/10.1016/j.compositesb.2013.10.007 FIB Bulletin 38 Fire design of concrete structures – materials, structures and modelling – state of art report, 2007, Fédération Internationale du Béton, Lausanne, Switzerland Bisby LA, Green MF, Kodur VKR (2005) Response to fire of concrete structures that incorporate FRP. Prog Struct Mat Eng 7(3):136–149. 10.1002/pse.198 CSA S806 (2002) Design and construction of building components with fibre-reinforced polymers. Can Stand Association Rosa IC, Firmo JP, Correia JR (2022) Experimental study of the tensile behaviour of GFRP reinforcing bars at elevated temperatures. Constr Build Mater 324:126676. https://doi.org/10.1016/j.conbuildmat.2022.126676 Wang YC, Wong PMH, Kodur V (2007) An experimental study of the mechanical properties of fibre reinforced polymer (FRP) and steel reinforcing bars at elevated temperatures. Compos Struct 80(1):131–140. 10.1016/j.compstruct.2006.04.069 Abbasi A, Hogg PJ (2005) A model for predicting the properties of the constituents of a glass fibre rebar reinforced concrete beam at elevated temperatures simulating a fire test. Compos B Eng 36(5):384–393. https://doi.org/10.1016/j.compositesb.2005.01.005 Nigro E, Cefarelli G, Bilotta A, Manfredi G, Cosenza E (2011) Fire resistance of concrete slabs reinforced with FRP bars. Part I: Experimental investigations on the mechanical behavior. Compos B Eng 42(6):1739–1750. https://doi.org/10.1016/j.compositesb.2011.02.025 Katz A, Berman N, Bank LC (1999) Effect of high temperature on bond strength of FRP rebars, Journal of Composites for Construction , vol. 3, no. 2, pp. 73–81, doi: 10.1061/(ASCE)1090-0268(1999)3:2(73) Bakis CE (1993) FRP Reinforcement: Materials and Manufacturing. Fiber-Reinforced-Plastic (FRP) Reinforcement for Concrete Structures. Elsevier, A. NANNI, Ed., Oxford, pp 13–58. doi: https://doi.org/10.1016/B978-0-444-89689-6.50006-9 . Calvet V, Valcuende M, Benlloch J, Cánoves J (2015) Influence of moderate temperatures on the bond between carbon fibre reinforced polymer bars (CFRP) and concrete. Constr Build Mater 94:589–604. https://doi.org/10.1016/j.conbuildmat.2015.07.053 Solyom S, Di Benedetti M, Guadagnini M, Balázs GL (2020) Effect of temperature on the bond behaviour of GFRP bars in concrete. Compos B Eng 183:107602. https://doi.org/10.1016/j.compositesb.2019.107602 Banerji S, Kodur V (Apr. 2023) Numerical model for tracing the response of Ultra-High performance concrete beams exposed to fire. Fire Mater 47(3):322–340. https://doi.org/10.1002/fam.3099 ISO 834 (1999) Geneva Bolina F, Tutikian B, Rodrigues JPC (2021) Thermal analysis of steel decking concrete slabs in case of fire. Fire Saf J 121:103295. https://doi.org/10.1016/j.firesaf.2021.103295 Bolina FL, Schallenberger M, Carvalho H (2023) Experimental and numerical evaluation of RC ribbed slabs in fire conditions, Structures , vol. 51, pp. 747–759, https://doi.org/10.1016/j.istruc.2023.03.057 Bolina FL, Poleto G, Carvalho H (2023) Proposition of parametric data for UHPC at high temperatures. J Building Eng 76:107222. https://doi.org/10.1016/j.jobe.2023.107222 Bolina FL, Rodrigues JPC (2023) Finite element analysis criteria for composite steel decking concrete slabs subjected to fire. Fire Saf J 139:103818. https://doi.org/10.1016/j.firesaf.2023.103818 Kodur VKR, Phan L (2007) Critical factors governing the fire performance of high strength concrete systems. Fire Saf J 42:6–7. 10.1016/j.firesaf.2006.10.006 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 26 Oct, 2024 Read the published version in Journal of Building Pathology and Rehabilitation → Version 1 posted Editorial decision: Revision requested 07 Oct, 2024 Reviews received at journal 07 Oct, 2024 Reviews received at journal 04 Oct, 2024 Reviewers agreed at journal 22 Sep, 2024 Reviewers agreed at journal 20 Sep, 2024 Reviewers invited by journal 03 Sep, 2024 Editor assigned by journal 03 Sep, 2024 Submission checks completed at journal 02 Sep, 2024 First submitted to journal 29 Aug, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-5000212","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":357460291,"identity":"a965f508-38fe-4d6d-a58f-368eb132b28b","order_by":0,"name":"Fabricio Longhi Bolina","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA80lEQVRIiWNgGAWjYBAC9gYeBoYEBgkGAwbmhgMMDDZAMcbGA/i08ByAa2EEaUkDaWkgrAUEQFqA1GEwB78W9rPHPjyosZAzZ29sPFxQc95ubfthoC01NtE4tfDkJc9IOCZhbNlzsOHwjGO3k7edSQRqOZaW24BDiz1DjjFDYoNE4oYbiQ2HedhuJ5sdAGphbDiMUwsP/xtkLf/OJZudf0hAiwSyLbxtB+zMbhCyReJdMgPcL7x9yQlmN4C2JODxCw9/7mHGHzV1wBBrPvyZ55udvdn59IcPPtTY4NSCARLBKhOIVQ4C9qQoHgWjYBSMgpEBAA+lZWNTVdw7AAAAAElFTkSuQmCC","orcid":"","institution":"Universidade Federal de Santa Maria","correspondingAuthor":true,"prefix":"","firstName":"Fabricio","middleName":"Longhi","lastName":"Bolina","suffix":""},{"id":357460293,"identity":"b190fbe7-26cc-40ae-bb71-a7c3cfa8db86","order_by":1,"name":"Débora Bretas Silva","email":"","orcid":"","institution":"Universidade Federal de Santa Maria","correspondingAuthor":false,"prefix":"","firstName":"Débora","middleName":"Bretas","lastName":"Silva","suffix":""},{"id":357460295,"identity":"a0a69b29-00b2-4c67-8d18-3f44929bf2e7","order_by":2,"name":"Eduardo Cesar Pachla","email":"","orcid":"","institution":"Universidade Federal de Santa Maria","correspondingAuthor":false,"prefix":"","firstName":"Eduardo","middleName":"Cesar","lastName":"Pachla","suffix":""}],"badges":[],"createdAt":"2024-08-29 23:54:09","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5000212/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5000212/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s41024-024-00530-3","type":"published","date":"2024-10-26T15:57:12+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":67117704,"identity":"bfcbf612-8203-4d87-9f06-0caedf172445","added_by":"auto","created_at":"2024-10-21 10:46:06","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":68946,"visible":true,"origin":"","legend":"\u003cp\u003eCross-section set-up: temperature control points\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-5000212/v1/d6895bdbef9fcd3e5952f5ca.png"},{"id":67117703,"identity":"839bf1be-5222-4c77-aee4-a2d6b588b7c2","added_by":"auto","created_at":"2024-10-21 10:46:06","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":27362,"visible":true,"origin":"","legend":"\u003cp\u003eHeating criteria for the beam and initial and fire conditions\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-5000212/v1/6aa2415c81f9dbab10b34bfe.png"},{"id":67118813,"identity":"a8c66f79-85de-4e1a-bd96-0c21d7e91014","added_by":"auto","created_at":"2024-10-21 10:54:06","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":82524,"visible":true,"origin":"","legend":"\u003cp\u003eAverage temperature in concrete\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-5000212/v1/213ca2e0133e9409ae766e40.png"},{"id":67117706,"identity":"2791adef-7eb6-41bc-8c3b-839ccd3f5a54","added_by":"auto","created_at":"2024-10-21 10:46:06","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":55288,"visible":true,"origin":"","legend":"\u003cp\u003eAverage temperature in positive reinforcements\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-5000212/v1/50c0acbd6b9ff7b36580d3a8.png"},{"id":67118812,"identity":"8981bfee-ab4a-4d42-b96d-1860cdce4f8a","added_by":"auto","created_at":"2024-10-21 10:54:06","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":47428,"visible":true,"origin":"","legend":"\u003cp\u003eAverage temperature in negative reinforcements\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-5000212/v1/040f9280aa298b839d651ac4.png"},{"id":67117712,"identity":"884a49f4-5230-474c-8b82-000f1e5e4a75","added_by":"auto","created_at":"2024-10-21 10:46:06","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":81573,"visible":true,"origin":"","legend":"\u003cp\u003eTemperature field on beam B5w35h50\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-5000212/v1/01727160dc6a0b33fc0c56fd.png"},{"id":67117711,"identity":"a6df2c4c-07af-476c-a0a5-249bbfeddff6","added_by":"auto","created_at":"2024-10-21 10:46:06","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":95760,"visible":true,"origin":"","legend":"\u003cp\u003eTemperature field on beam B7w20h70\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-5000212/v1/b67a2cf4693307d1b28f6d44.png"},{"id":67117708,"identity":"27da43ca-2ee3-4ff9-bc67-8086c15bc461","added_by":"auto","created_at":"2024-10-21 10:46:06","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":41135,"visible":true,"origin":"","legend":"\u003cp\u003eFire resistance rating (FRR) of beams based on the critical temperature of the concrete\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-5000212/v1/df99b46b910ca68275acc75d.png"},{"id":67118814,"identity":"7ab28275-1ef5-4e9b-b2eb-6696938a083a","added_by":"auto","created_at":"2024-10-21 10:54:06","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":18537,"visible":true,"origin":"","legend":"\u003cp\u003eFire resistance rating (FRR) of beams based on the critical temperature of the positive reinforcements\u003c/p\u003e","description":"","filename":"9.png","url":"https://assets-eu.researchsquare.com/files/rs-5000212/v1/ad7fde75d9dd962427295eb9.png"},{"id":67119504,"identity":"718da309-307f-4193-8800-5273c42733de","added_by":"auto","created_at":"2024-10-21 11:02:06","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":24512,"visible":true,"origin":"","legend":"\u003cp\u003eFire resistance rating (FRR) of beams based on the critical temperature of the negative reinforcements\u003c/p\u003e","description":"","filename":"10.png","url":"https://assets-eu.researchsquare.com/files/rs-5000212/v1/3d1ec5320582ecbc141be288.png"},{"id":67681736,"identity":"4944fce9-ef81-44f6-b7a9-84228abd974a","added_by":"auto","created_at":"2024-10-28 16:09:26","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":914699,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5000212/v1/46d78c5f-85d4-4d44-b622-7d2f4aa07f8d.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"The fire performance of GFRP-RC beams based on FE thermal analysis","fulltext":[{"header":"1 INTRODUCTION","content":"\u003cp\u003eThe service life of concrete structures has become increasingly important in recent years. The use of steel-reinforced concrete in areas with high chloride concentrations (e.g., coastal areas, seawater and de-icing salts) or chemical and radioactive wastes (e.g., in industrial facilities) can lead to corrosion of the steel rebars [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e], resulting in concrete spalling [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e] and weakening structural integrity [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e], reducing the service life and structural performance [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Durability requirements must be considered in any structural design. When predicting service life, it is usually conservatively assumed that the service life ends when corrosion begins [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e], which is typically solved in design by incorporating a minimum concrete cover thickness to protect the steel reinforcements [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e], [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAn alternative to solving the durability requirement is to use fiber reinforced polymer (FRP) rebars in place of the traditional steel [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. The material is corrosion-resistant [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. In addition, these composite materials are not only lighter than steel, but they also have higher tensile strength, electromagnetic transparency and low maintenance requirements [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. FRP rebars enable thinner structural cross-sections with high reinforcement density by reducing the thickness of the concrete cover. Studies have demonstrated the application of FRP rebars in bridge decks [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e], structural walls [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e], industrial [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e], maritime [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e] and also infrastructure constructions [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e] and others. Glass FRP (GFRP) is the most commonly used for concrete because it is less expensive and has acceptable mechanical properties for use in concrete structures [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e], [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eGFRP reinforcement is a composite material and are an attractive alternative to steel rebars to ensure long-term structural performance [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. A low weight and high strength compared to conventional steel is an interesting advantage of this solution [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. A high corrosion resistance, high strength-to-weight ratio, high stiffness-to-weight ratio, high degree of chemical inertia, excellent fatigue tolerance is another advantage to use the GFRP rebars (GFRP-R) [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. The sustainability is a point of interest, measured by its associated economic and environmental impacts throughout its life cycle [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. However, the benefits of GFRP-R instead of classical steel reinforcement are not exploited due to their vulnerability at high temperatures and under fire [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Mechanical properties of GFRP materials degrade significantly in this environment, leading to a serious and significant reduction in bearing capacity and brittle failure of GFRP-RC structures [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e], mainly due to the tensile strength and elastic modulus damage [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eFire is one of the most serious potential risks for buildings and structures, and for this reason international codes provide specific guidelines to take account this scenario in the design of structures [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. GFRP-R are more vulnerable to high temperatures than steel rebars [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e], [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e], [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e], highlighting an issue to be addressed. The fire sensitivity of GFRP-R limits their wide use in construction. As seen in the steel reinforcements, the physical and mechanical properties of GFRP decrease at high temperatures. Material degradation is the key phenomenon, but it must meet the requirements of the relevant fire codes to be used as a structural solution. Most of these refer to the time available in a fire before the structural failure [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eExtensive studies are available on the high temperature behavior of concrete reinforced with steel rebars, and their fire behavior is well known and also prescribed by many standardized procedures [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e], [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e], [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. However, there is a gap in the literature regarding the analysis of concrete structures reinforced with GFRP-R subjected to fire. In the case of Brazil [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e], as well as in the European standard [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e], there are no proposed design procedures for the fire design of these structures. Due to the lack of knowledge, design guidelines (conservatively) do not recommend yet the use of GFRP rebars in structures where the fire action has to be considered at design (i.e., in buildings) [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThere are many philosophies on the design of concrete structures in fire. The most usual is to limit the reinforcement to reach a critical temperature. This method is well accepted due to the low thermal diffusivity of concrete and makes the reinforcement the critical component of the structure. In the case of the steel rebars, this temperature is in order of 500\u0026deg;C, as proposed by fib Bulettin No.38 [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. At critical temperature steel loses around half of its original strength, and the structure can no longer support the loads during a fire. An adequate fire design for reinforced concrete could be achieved by providing minimum dimensions and sufficient concrete cover thickness to protect the reinforcement [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. Standards as CSA S806 [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e] continue to use the temperature in the GFRP-R as a critical criterion to design the GFRP-RC structures, clearly based on the philosophy established to traditional RC structures.\u003c/p\u003e \u003cp\u003eThe reduction in strength with increasing temperature varies considerably depending on the type of fiber and resin [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. The tensile strength is significantly more affected by elevated temperature than the elastic modulus, but some authors highlight that the fire performance of these rebars is unclear [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Wang et al. [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e] suggested a critical temperature based on 50% strength loss is 325\u0026deg;C. As the ultimate temperature, Abbasi and Hogg [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e] proposed 462\u0026deg;C, while the experimental research done by Nigro et al. [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e] highlight 460\u0026deg;C. Hajiloo et al. [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e], Bilotta et al. [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e], and Jin et al. [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e] stablished 400\u0026deg;C as the ultimate temperature, but Rosa et al. [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e] suggests 300\u0026deg;C to structural design (where the 50% of the ultimate condition is reached). Around 700\u0026deg;C there is a full decomposition of the resin [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eHowever, the bond of the GFRP-R to concrete are damaged at 100\u0026deg;C, and this temperature need to be assumed as critical. Researches such as Katz et al. [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e] concluded that the bond performance at ambient temperature, as well as the bond strength and stiffness degradation with temperature, depend mostly on parameters associated with the surface properties of the rebars. According to the authors, at 200\u0026deg;C the GFRP bond strength are reduced at least 80%, while in the steel rebars are only 38%. The literature about the reduction with temperature of the bond properties of GFRP-R to concrete is still very limited [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. There are authors who believe that when continuous reinforcement from side to side of the RC element was used, not significant slips occurred at the end anchorage zones, and then the structural integrity was guaranteed [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eGlass fibers can resist 800\u0026deg;C [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e], but they do not perform their job perfectly in concrete elements without binding material (resin). In fact, according to Rosa et al. [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e], the effects of elevated temperatures on the bond between GFRP rebars and concrete are more severe than the mechanical loss of these rebars. Studies have already shown that when the glass transition temperature of the polymeric matrix is reached (approx. 100\u0026deg;C), the bond strength between GFRP-RC decreases by 90 % [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e], [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e], [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]. Thee results raise concerns about the performance of GFRP-RC structures exposed to fire, as most of the bond strength of the reinforcements is likely to be lost in the early stages of a fire while temperatures are still moderate [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Studies show that GFRP-RC structures exposed to fire fail prematurely because the bond is lost along the overlapping length of the rebars [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe aim of the proposed study was to understand the fire behavior of GFRP-RC structures. A thermal analysis of a group of rectangular beam cross-sections was proposed. A group of RC beams with different width and concrete cover was assumed. The average temperature of the concrete and reinforcement was considered. The uniqueness of the proposed research is to compare a series of RC beams with different widths and heights and variable concrete cover thicknesses to determine and correlate the fire behavior and the FRR of GFRP and conventional steel reinforcements when exposed to fire.\u003c/p\u003e"},{"header":"2 METHODS","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Research overview\u003c/h2\u003e \u003cp\u003eThe study attempts to better understand the fire behavior of GFRP-RC structures and their correlation with steel RC structures. A thermal analysis of several rectangular beam cross-sections was presented. Abaqus software was used to solve a set of finite elements (FE) models. A variety of RC beam widths and heights and concrete cover thicknesses were assumed. The average temperature of the concrete and reinforcement (assuming conventional steel and GFRP) was identified as a crucial criterion. A comparison was done.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Cross-sectional thermal analyses\u003c/h2\u003e \u003cp\u003eThe concrete cover (C) thickness criterion considered in structural fire design (\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{\\text{C}}_{\\text{f}}\\)\u003c/span\u003e\u003c/span\u003e) is not the same as the durability and service life requirements. The \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{\\text{C}}_{\\text{f}}\\)\u003c/span\u003e\u003c/span\u003e is measured from the edge of the beam to the center of longitudinal reinforcement, as shown in Fig.\u0026nbsp;1. It\u0026rsquo;s a standardized criterion. The section width (W) and height (H) were assumed as variables for the study. The thickness of the slab (\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{\\text{t}}_{\\text{s}}\\)\u003c/span\u003e\u003c/span\u003e) was 100 mm in all cases. The cross-section shown in Fig.\u0026nbsp;1a establishes the results to define the sagging bending resistant moment (+) of the RC beams (the concrete temperature above the neutral axis and the positive steel reinforcements as used in the conventional design procedure). The same in Fig.\u0026nbsp;1b, but to the hogging moment (-).\u003c/p\u003e\u003cp\u003eThe temperature time history in concrete (average between pt1 to pt5 control points) and reinforcement (average between Rb1 to Rb3 control points) temperatures was monitored to determine the thermal field of each selected cross section (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). For the concrete temperatures, since the concrete cross-section at the bearing capacity of the beam is above (in case of sagging moment) or below (hogging moment) the neutral axis, only measurement points in this region were assumed (i.e., 0.5 x H). The concrete temperature is the average of the control points pt1(+) to pt5(+) (in case of the sagging moment) and pt1(-) to pt5(-) (hogging moment). The beam cross-sections considered in the study are shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. The usual width and height of the beams (as is usual in engineering practice) were taken into account.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003e\u0026ndash; Beams assumed in the research\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"5\" nameend=\"c5\" namest=\"c1\"\u003e \u003cp\u003eCross-section characteristics and nomenclatures\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBeam number\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNomenclature\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eWidth W (mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eHeight H (mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{\\text{C}}_{\\text{f}}\\)\u003c/span\u003e\u003c/span\u003e thickness (mm)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eB1w15h50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e150\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e500\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e20 to 50\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eB2w20h50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e200\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e500\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e20 to 50\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eB3w25h50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e250\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e500\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e20 to 50\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eB4w30h50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e300\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e500\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e20 to 50\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eB5w35h50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e350\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e500\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e20 to 50\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eB6w20h60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e200\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e600\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e20 to 50\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eB7w20h70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e200\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e700\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e20 to 50\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eB8w20h80\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e200\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e800\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e20 to 50\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eB9w20h90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e200\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e900\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e20 to 50\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eB10w20h100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e200\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e20 to 50\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eAs shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, beams B1 to B5 were designed to investigate the effect of beam width on the average temperature of longitudinal reinforcements and concrete, while keeping the beam height fixed at 500 mm. Beams B6 to B10, on the other hand, fixed the beam width at 200 mm keeping the beam height as variable.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Numerical procedures\u003c/h2\u003e \u003cp\u003eConduction is the primary heat transfer process, while convection and radiation are the mechanisms for heat transfer from the environment to the structural surfaces exposed to fire [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]. Eq.\u0026nbsp;\u003cspan refid=\"Equ1\" class=\"InternalRef\"\u003e1\u003c/span\u003e shows that the thermal diffusivity is related to the mass loss \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\rho\\:\\)\u003c/span\u003e\u003c/span\u003e, the thermal conductivity \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\lambda\\:\\)\u003c/span\u003e\u003c/span\u003e and specific heat \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{C}_{p}\\)\u003c/span\u003e\u003c/span\u003e. In the case of concrete, these parameters are those proposed in EN 1992\u0026thinsp;\u0026minus;\u0026thinsp;1.2 [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. In the case of reinforcement, the thermal parameters are not required in the model, as described in section \u003cspan refid=\"Sec6\" class=\"InternalRef\"\u003e2.4\u003c/span\u003e.\u003cdiv id=\"Equ1\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ1\" name=\"EquationSource\"\u003e\n$$\\:{\\alpha\\:}=\\frac{{\\lambda\\:}}{{\\rho\\:}.{\\text{C}}_{\\text{p}}}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e1\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eThe governing equation for the convective and radiative heat transfer analysis are defined in Eq.\u0026nbsp;\u003cspan refid=\"Equ2\" class=\"InternalRef\"\u003e2\u003c/span\u003e [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e], where \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{\\text{n}}_{\\text{y}}\\)\u003c/span\u003e\u003c/span\u003e and \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{\\text{n}}_{\\text{z}}\\)\u003c/span\u003e\u003c/span\u003e are the components of the vector outward normal to the cross-sectional surface; \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{\\text{h}}_{\\text{r}\\text{a}\\text{d}}\\)\u003c/span\u003e\u003c/span\u003e and \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{\\text{h}}_{\\text{c}\\text{o}\\text{n}}\\)\u003c/span\u003e\u003c/span\u003e are the radiative and convective heat transfer coefficient, respectively; T is the initial temperature (20\u0026deg;C) and \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{\\text{T}}_{\\text{E}}\\)\u003c/span\u003e\u003c/span\u003e is the temperature of the environment (assumed as ISO 834 [\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e] according to the EN 1992\u0026thinsp;\u0026minus;\u0026thinsp;1.2 [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e] design procedure). The radiation heat transfer coefficient is given by Eq.\u0026nbsp;\u003cspan refid=\"Equ3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, where \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{\\sigma\\:}\\)\u003c/span\u003e\u003c/span\u003e is the Stefan-Boltzmann constant (σ\u0026thinsp;=\u0026thinsp;5.67 x 10\u003csup\u003e\u0026minus;\u0026thinsp;8\u003c/sup\u003e W/m\u0026sup2;.\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{^\\circ\\:\\text{C}}^{4}\\)\u003c/span\u003e\u003c/span\u003e), and \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{\\epsilon\\:}\\)\u003c/span\u003e\u003c/span\u003e the emissivity factor (0.70 according to EN 1992\u0026thinsp;\u0026minus;\u0026thinsp;1.2 [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]). The convective heat transfer 25 and 9 W/m\u0026sup2;\u0026deg;C in the fire-exposed and unexposed surface.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Equ2\" class=\"Equation\"\u003e \u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ2\" name=\"EquationSource\"\u003e\n$$\\:\\text{k}\\bullet\\:\\left(\\frac{\\text{d}\\text{T}}{\\text{d}\\text{y}}\\bullet\\:{\\text{n}}_{\\text{y}}+\\frac{\\text{d}\\text{T}}{\\text{d}\\text{z}}\\bullet\\:{\\text{n}}_{\\text{z}}\\right)=-\\left({\\text{h}}_{\\text{r}\\text{a}\\text{d}}+{\\text{h}}_{\\text{c}\\text{o}\\text{n}}\\right)\\bullet\\:\\left(\\text{T}-{\\text{T}}_{\\text{E}}\\right)$$\u003c/div\u003e \u003cdiv class=\"EquationNumber\"\u003e2\u003c/div\u003e\u003c/div\u003e \u003cdiv id=\"Equ3\" class=\"Equation\"\u003e \u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ3\" name=\"EquationSource\"\u003e\n$$\\:{\\text{h}}_{\\text{r}\\text{a}\\text{d}}=4\\bullet\\:{\\sigma\\:}\\bullet\\:{\\epsilon\\:}\\bullet\\:\\left({\\text{T}}^{2}+{\\text{T}}_{\\text{E}}^{2}\\right)\\bullet\\:\\left(\\text{T}+{\\text{T}}_{\\text{E}}\\right)$$\u003c/div\u003e \u003cdiv class=\"EquationNumber\"\u003e3\u003c/div\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eHeating was applied to both lateral surfaces and one lower surface of the beam, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe 3D model using thermal transient non-linear analysis is used to solved the problem. The concrete was modeled as DC3D8 finite element with classical integration from the ABAQUS library. A mesh analysis was performed and the mesh is rather refined, the size of the elements is approximately 1.0 x 1.0 x 1.0 mm. The time increment used was 0.001s and a convergence criterion of 0.1\u0026ordm;C.\u003c/p\u003e \u003cp\u003eThe DC3D8 assumes a single degree of freedom (temperature) at each node along the x, y, and z axis. The solution used to solve the thermal problem is shown in Eq.\u0026nbsp;\u003cspan refid=\"Equ4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, where the coefficients follow the same criteria and descriptions detailed in Eq.\u0026nbsp;\u003cspan refid=\"Equ1\" class=\"InternalRef\"\u003e1\u003c/span\u003e to \u003cspan refid=\"Equ3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, where \u0026ldquo;t\u0026rdquo; is the time. The temperature distribution in the cross-section is obtained through conduction thermal analysis, and the heat transfer equation is formulated by applying the principle of conservation of the energy to a three-dimensional differential control volume.\u003cdiv id=\"Equ4\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ4\" name=\"EquationSource\"\u003e\n$$\\:\\frac{\\partial\\:}{\\partial\\:\\text{x}}\\left({\\lambda\\:}\\frac{\\partial\\:{\\theta\\:}}{\\partial\\:\\text{x}}\\right)+\\frac{\\partial\\:}{\\partial\\:\\text{y}}\\left({\\lambda\\:}\\frac{\\partial\\:{\\theta\\:}}{\\partial\\:\\text{y}}\\right)+\\frac{\\partial\\:}{\\partial\\:\\text{z}}\\left({\\lambda\\:}\\frac{\\partial\\:{\\theta\\:}}{\\partial\\:\\text{z}}\\right)={\\rho\\:}\\bullet\\:{\\text{C}}_{\\text{p}}\\bullet\\:\\frac{\\partial\\:{\\theta\\:}}{\\partial\\:\\text{t}}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e4\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eWhere \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\frac{\\partial\\:{\\theta\\:}}{\\partial\\:\\text{x}}\\)\u003c/span\u003e\u003c/span\u003e, \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\frac{\\partial\\:{\\theta\\:}}{\\partial\\:\\text{y}}\\)\u003c/span\u003e\u003c/span\u003e and \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\frac{\\partial\\:{\\theta\\:}}{\\partial\\:\\text{z}}\\)\u003c/span\u003e\u003c/span\u003e is the temperature \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{\\theta\\:}\\)\u003c/span\u003e\u003c/span\u003e gradient in the x, y and z-directions, and the \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{\\rho\\:}\\bullet\\:{\\text{C}}_{\\text{p}}\\bullet\\:\\frac{\\partial\\:{\\theta\\:}}{\\partial\\:\\text{t}}\\)\u003c/span\u003e\u003c/span\u003e is the time rate of change of the thermal energy of the medium per unit volume. In the case of the thermal boundary conditions, the exchange of convection and radiation during the heating process was considered.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e2.4 Reinforcements assumptions\u003c/h2\u003e \u003cp\u003eNo reinforcement was used in the cross-section as its area is much smaller than that of concrete. The study focuses on the average temperature of the concrete cross-section and defines the reinforcement temperature assuming the concrete temperature in the same layer where the reinforcement is placed. Previous numerical FE studies by the authors, confirmed by full-scale experimental results (see [\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e], [\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e]), have already shown that the lack of reinforcement in the thermal model has little effect on the thermal field in the cross-section. The small cross-sectional area of the reinforcements compared to the total area of the concrete and the high thermal conductivity of the steel may contribute to the explanation.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e2.5 Validation of the FEA model and numerical procedure\u003c/h2\u003e \u003cp\u003eThe FE model proposed in this research and the numerical procedure to solve the heat transfer problem (mesh size, steps, boundary conditions, integration process, governing equations, etc.) were validated by the authors through an extensive full-scale test (heating according to ISO 834 [\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e]) which they carried out in various studies. Some of these can be found in research papers such as [\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e], [\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e], [\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e]. The FEA model and numerical simulation were also based on the approaches highlighted by the authors in [\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e"},{"header":"3 RESULTS AND DISCUSSIONS","content":"\u003cp\u003eThe temperature history in the concrete and in the positive and negative reinforcement is shown above. The temperature field in the cross-section and the fire resistance rate (FRR) of each beam, which are listed in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, are also shown.\u003c/p\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e3.1 Concrete\u003c/h2\u003e \u003cp\u003eThe temperature history in the concrete is shown in Fig.\u0026nbsp;3.\u003c/p\u003e \u003cp\u003eThe temperature above (Fig.\u0026nbsp;3a) and below (Fig.\u0026nbsp;3b) the neutral axis is described. The temperature refers to the average of the points pt1 to pt5 (see Fig.\u0026nbsp;1). The critical temperature of the concrete (approx. 350\u0026deg;C) is also highlighted in the curves. The temperature above and below the neutral axis is elementary for the determination of the sag or hogging moment, if the usual analytical expressions for determining the bending capacity of these structures are taking into account.\u003c/p\u003e \u003cp\u003eThe average temperature in the cross-section of the beams naturally depends on their geometry. The most important factor influencing the average temperature of the concrete (above or below the neutral axis) is the width of the beam.\u003c/p\u003e \u003cp\u003eAbove the neutral axis analysis: at the end of the numerical analysis, the temperature difference between B1 and B5 is about 300\u0026deg;C, as shown in Fig.\u0026nbsp;3a. Assuming the height of the beam, the difference between B6 and B10 is no more than 50\u0026deg;C. Only B1, B2 and B6 to B10 reached the temperature that characterizes critical mechanical damage of the concrete, i.e., only the beams with 15 and 20 cm width. Beams with a width of more than 20 cm did not reach the critical temperature of the concrete.\u003c/p\u003e \u003cp\u003eBelow the neutral axis analysis: it is most affected by the high temperatures, as the three sides of this area of the beam are exposed to fire (see Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e2\u003c/span\u003e). As described in Fig.\u0026nbsp;3a, Fig.\u0026nbsp;3b also shows that the width of the beam has less influence on the temperature field in the cross-section than the height. At the end of the analysis, the difference between B1 and B5 (with a width of 15 and 35 cm respectively) is almost 400\u0026deg;C, while between B6 and B9 (with a height of 60 and 90 cm respectively) is no more than 50\u0026deg;C. It is also important to note that the critical temperature of the concrete is reached in all cases. B1 is the most critical condition, while B5 is the most stable in the fire. With regard to the concrete temperature, the width of the beams is decisive for their fire behavior.\u003c/p\u003e \u003cp\u003eThe critical temperature of the concrete must be discussed in parallel with the reinforcement to predict the structural fire behavior. The positive and negative reinforcement temperatures are discussed below.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003e3.2 Positive reinforcements\u003c/h2\u003e \u003cp\u003eFigures 4a, 4b, 4c and 4d show the temperature history in the reinforcements with C\u0026thinsp;=\u0026thinsp;20, 30, 40 and 50 mm. The critical temperature of steel and GFRP reinforcements is also highlighted. The temperature history in the positive reinforcements is required to define and apply the analytical expressions for determining the sagging bending resistance moment in fire.\u003c/p\u003e \u003cp\u003eThe average temperature of the reinforcement is directly dependent on the thickness of the concrete cover. In general, the temperature of the reinforcement decreases in the order of 100\u0026deg;C to each 10 mm increase in concrete cover. Since the critical temperature of conventional steel reinforcement is five times higher than that of GFRP reinforcement, the FRR of these beams naturally tends to be higher. Assuming that C\u0026thinsp;=\u0026thinsp;10, 20 or 30 mm, the GFRP beams do not reach 20 min to standard fire, while the beams with conventional steel rebars reach about 40, 60 and 70 min, respectively. The FRR of the conventional steel RC beam is at least 80 min and can reach a maximum of 110 min, depending on the beam width. At 50 mm, the FRR of the GFRP RC beam is approximately 30 min.\u003c/p\u003e \u003cp\u003eIt is important to note that in the most critical condition, the FRR of steel RC beams can exceed 80 minutes compared to GFRP RC structures. This condition highlights the safety of conventional steel RC structures in terms of fire performance and also the shortcomings that need to be discussed in order to apply GFRP reinforcement in conventional multi-storey buildings when fire safety requirements need to be met\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003e3.3 Negative reinforcements\u003c/h2\u003e \u003cp\u003eThe temperature in negative reinforcements with C\u0026thinsp;=\u0026thinsp;20, 30, 40 and 50 mm is shown in Figs.\u0026nbsp;5a, 5b, 5c and 5d respectively. These rebars are more thermally protected compared to the positive rebars due to the adjacent slab. These temperatures are necessary to define and apply the analytical expressions required to determine the hogging bending resistance moment in case of fire.\u003c/p\u003e \u003cp\u003eFigure 5 shows that high temperatures have no effect on steel reinforcement. This indicates that with the proposed cross-sectional dimensions of the beams (as given in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e), these reinforcements don't shown mechanical damage when the beam is exposed to fire. In contrast, the GFRP reinforcements with C\u0026thinsp;=\u0026thinsp;20, 30, 40 and 50 mm reached their critical temperature at 90, 85, 80 and 75 min of fire exposure respectively. It's important to remember that the thickness C is counted for the surface of the beam. As the C thickness increases, the rebars are exposed to higher temperatures, which reduces their FRR tine.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003e3.4 Temperature field in the cross-section\u003c/h2\u003e \u003cp\u003eFigures 6 and 7 show the temperature field in cross-section for two cases of beams when B5w35h50 and B7w20h70 are described, respectively. These isotherms confirm the results shown in the previous sections of the study and also illustrate the heterogeneity of the temperature distribution in the cross-section. When increasing exposure time to the ISO 834 temperature, the thermal field and thus the average temperature in the concrete and in the reinforcement also improves. These temperatures cause mechanical damage to the materials (i.e., concrete and steel or GFRP reinforcements), which can lead to failure of the beam and any RC structure.\u003c/p\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003e3.5 Ultimate condition in fire\u003c/h2\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e8\u003c/span\u003e shows the FRR for each beam proposed in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e when the critical concrete temperature (350\u0026deg;C) is reached. The concrete above and below the neutral axis, which is required to define the sagging and the hogging bending resistant moment in case of fire with the analytical expressions, respectively, has been considered. As expected, the compressive concrete below the neutral axis, which is required to determine the hogging moment, is most damaged by the fire. The concrete below the neutral axis develops a lower average temperature, which is partly due to the adjacent slab in this area. Comparing Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e8\u003c/span\u003e with Figs.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e9\u003c/span\u003e and \u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e10\u003c/span\u003e, it is clear that the temperature of the reinforcement is crucial to justify the failure of the beams exposed to fire.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e9\u003c/span\u003e and Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e10\u003c/span\u003e show the FRR time assuming the critical temperature in the positive and negative reinforcement for conventional steel and GFRP rebars, respectively. Regarding negative reinforcement, the beams with conventional steel rebars have an FRR\u0026thinsp;\u0026gt;\u0026thinsp;180 min. This time is not exactly determined because the numerical analysis ends at 180 min (as standardized building requirements often do not require FRR more than 180 min, which justify the authors criteria).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAssuming the positive reinforcement temperatures shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e9\u003c/span\u003e, which represents the critical case of the fire-exposed beams, the FRR of the conventional steel RC beams was 401.1, 419.5, 375.0, and 348.4% higher than that of the identical GFRP RC beams at C\u0026thinsp;=\u0026thinsp;20, 30, 40, and 50 mm. It is to be expected that the GFRP-RC beams will fail quickly in fire, which shows a major inconsistency in the technical application of these rebars. Of course, there is great interest in these reinforcements due to the aggressiveness of the environment (especially the chemical environment), but since the building must also meet a variety of performance requirements, the use of these rebars must be reconsidered in some cases.\u003c/p\u003e \u003c/div\u003e"},{"header":"4 CONCLUSIONS","content":"\u003cp\u003eThe main conclusions of this research were:\u003c/p\u003e \u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003eThe width is the main factor influencing the average temperature of the concrete in the cross-section of the beam;\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eGFRP RC beams with a concrete cover thickness of 20, 30 and 40 mm do not reach the 20 min of the ISO 834 fire. It is to be expected that these beams will fail very quickly when subjected to high temperatures;\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eIn terms of fire resistance time, concrete beams with conventional steel reinforcement may have a fire performance - in some cases - four times higher than identical reinforced concrete structures with GFRP rebars;\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eTaking into account typical cross-sectional dimensions of the RC beams, the negative GFRP reinforcement was damaged by the fire, while identical beams with steel reinforcement were not damaged;\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eThe study shows a contradiction: the lower concrete cover thickness of GFRP rebars compared to traditional steel rebars is advantageous in terms of environmental aggressiveness, but undesirable in terms of fire safety criteria. The susceptibility of GRP rebars to fire may help to explain this;\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eIn certain circumstances, the use of GFRP RC structures instead of the usual steel RC structures must be investigated and discussed, especially if the building has to meet fire safety requirements;\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eAs future research, the authors suggest considering the fire sensitivity of these reinforcements and finding a technical solution to improve the thermal and mechanical properties of the GFRP rebars at high temperatures.\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eFLB: conceptualization, data curation, formal analysis, numerical analysis, writing original text; DBS: conceptualization, formal analysis; ECP: conceptualization, formal analysis.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003ePillai RG et al (2019) Service life and life cycle assessment of reinforced concrete systems with limestone calcined clay cement (LC3). Cem Concr Res 118:111\u0026ndash;119. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.cemconres.2018.11.019\u003c/span\u003e\u003cspan address=\"10.1016/j.cemconres.2018.11.019\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBilcik J, Holly I (2013) Effect of Reinforcement Corrosion on Bond Behaviour. Procedia Eng 65:248\u0026ndash;253. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.proeng.2013.09.038\u003c/span\u003e\u003cspan address=\"10.1016/j.proeng.2013.09.038\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRamanathan S, Benzecry V, Suraneni P, Nanni A (2021) Condition assessment of concrete and glass fiber reinforced polymer (GFRP) rebar after 18 years of service life. Case Stud Constr Mater 14:e00494. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.cscm.2021.e00494\u003c/span\u003e\u003cspan address=\"10.1016/j.cscm.2021.e00494\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAbbas H, Abadel A, Almusallam T, Al-Salloum Y (2022) Experimental and analytical study of flexural performance of concrete beams reinforced with hybrid of GFRP and steel rebars. Eng Fail Anal 138:106397. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.engfailanal.2022.106397\u003c/span\u003e\u003cspan address=\"10.1016/j.engfailanal.2022.106397\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSafehian M, Ramezanianpour AA (2013) Assessment of service life models for determination of chloride penetration into silica fume concrete in the severe marine environmental condition. Constr Build Mater 48:287\u0026ndash;294. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.conbuildmat.2013.07.006\u003c/span\u003e\u003cspan address=\"10.1016/j.conbuildmat.2013.07.006\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNBR 6118 (2023) Design of reinfoced concrete structures - procedures (in Portuguese). Brazilian Natl Stand Organ\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eEN 1992\u0026thinsp;\u0026ndash;\u0026thinsp;1 (2004) 1, Eurocode 2: Design of concrete structures - Part 1\u0026ndash;1: General rules and rules for buildings. Eur Comm Stand\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRosa IC, Firmo JP, Correia JR, Barros JAO (2019) Bond behaviour of sand coated GFRP bars to concrete at elevated temperature \u0026ndash; Definition of bond vs. slip relations. Compos B Eng 160:329\u0026ndash;340. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.compositesb.2018.10.020\u003c/span\u003e\u003cspan address=\"10.1016/j.compositesb.2018.10.020\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBenmokrane B, Ali AH, Mohamed HM, ElSafty A, Manalo A (2017) Laboratory assessment and durability performance of vinyl-ester, polyester, and epoxy glass-FRP bars for concrete structures. Compos B Eng 114:163\u0026ndash;174. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.compositesb.2017.02.002\u003c/span\u003e\u003cspan address=\"10.1016/j.compositesb.2017.02.002\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBank LC (2006) Composite for construction - structural design with FRP materials. Wiley, New Jersey\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCorreia JR, Bai Y, Keller T (2015) A review of the fire behaviour of pultruded GFRP structural profiles for civil engineering applications. Compos Struct 127:267\u0026ndash;287. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.compstruct.2015.03.006\u003c/span\u003e\u003cspan address=\"10.1016/j.compstruct.2015.03.006\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKim GB, Pilakoutas K, Waldron P (2008) Thin FRP/GFRC structural elements. Cem Concr Compos 30(2):122\u0026ndash;137. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.cemconcomp.2007.04.011\u003c/span\u003e\u003cspan address=\"10.1016/j.cemconcomp.2007.04.011\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHajiloo H, Green MF, Gales J (2018) Mechanical properties of GFRP reinforcing bars at high temperatures. Constr Build Mater 162:142\u0026ndash;154. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.conbuildmat.2017.12.025\u003c/span\u003e\u003cspan address=\"10.1016/j.conbuildmat.2017.12.025\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRosa IC, Firmo JP, Correia JR, Mazzuca P (2021) Influence of elevated temperatures on the bond behaviour of ribbed GFRP bars in concrete. Cem Concr Compos 122:104119. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.cemconcomp.2021.104119\u003c/span\u003e\u003cspan address=\"10.1016/j.cemconcomp.2021.104119\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eIlg P, Hoehne C, Guenther E (2016) High-performance materials in infrastructure: a review of applied life cycle costing and its drivers \u0026ndash; the case of fiber-reinforced composites. J Clean Prod 112:926\u0026ndash;945. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jclepro.2015.07.051\u003c/span\u003e\u003cspan address=\"10.1016/j.jclepro.2015.07.051\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYounis A, Ebead U, Judd S (2018) Life cycle cost analysis of structural concrete using seawater, recycled concrete aggregate, and GFRP reinforcement. Constr Build Mater 175:152\u0026ndash;160. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.conbuildmat.2018.04.183\u003c/span\u003e\u003cspan address=\"10.1016/j.conbuildmat.2018.04.183\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCadenazzi T, Dotelli G, Rossini M, Nolan S, Nanni A (2020) Cost and environmental analyses of reinforcement alternatives for a concrete bridge, \u003cem\u003eStructure and Infrastructure Engineering\u003c/em\u003e, vol. 16, no. 4, pp. 787\u0026ndash;802, Apr. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1080/15732479.2019.1662066\u003c/span\u003e\u003cspan address=\"10.1080/15732479.2019.1662066\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBilotta A, Compagnone A, Esposito L, Nigro E (2020) Structural behaviour of FRP reinforced concrete slabs in fire. Eng Struct 221:111058. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.engstruct.2020.111058\u003c/span\u003e\u003cspan address=\"10.1016/j.engstruct.2020.111058\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJin L, Liu Y, Zhang R, Du X (2024) Out-of-plane impact behavior and post-impact damage evaluation of GFRP bar-reinforced concrete shear walls in fire. J Building Eng 94:109942. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jobe.2024.109942\u003c/span\u003e\u003cspan address=\"10.1016/j.jobe.2024.109942\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJafarzadeh H, Nematzadeh M (2022) Flexural strengthening of fire-damaged GFRP-reinforced concrete beams using CFRP sheet: Experimental and analytical study. Compos Struct 288:115378. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.compstruct.2022.115378\u003c/span\u003e\u003cspan address=\"10.1016/j.compstruct.2022.115378\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eThongchom C et al (2023) Experimental and Numerical Investigation of Steel- and GFRP-Reinforced Concrete Beams Subject to Fire Exposure. Buildings 13(3). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3390/buildings13030609\u003c/span\u003e\u003cspan address=\"10.3390/buildings13030609\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCarvelli V, Pisani MA, Poggi C (2013) High temperature effects on concrete members reinforced with GFRP rebars. Compos B Eng 54:125\u0026ndash;132. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.compositesb.2013.05.013\u003c/span\u003e\u003cspan address=\"10.1016/j.compositesb.2013.05.013\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNBR 15200 (2024) Design of reinforced concrete structures in case of fire (in Portuguese). Brazilian Natl Stand Organ\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eEN 1992\u0026thinsp;\u0026ndash;\u0026thinsp;1.2 (2004) Eurocode 2: Design of concrete structures - Part 1\u0026ndash;2: General rules - Structural fire design. Eur Comm Stand\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eACI 318 (2014) Building Code Requirements for Structural Concrete. Am Concrete Inst (ACI)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNigro E, Cefarelli G, Bilotta A, Manfredi G, Cosenza E (2014) Guidelines for flexural resistance of FRP reinforced concrete slabs and beams in fire. Compos B Eng 58:103\u0026ndash;112. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.compositesb.2013.10.007\u003c/span\u003e\u003cspan address=\"10.1016/j.compositesb.2013.10.007\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFIB Bulletin 38 Fire design of concrete structures \u0026ndash; materials, structures and modelling \u0026ndash; state of art report, 2007, \u003cem\u003eF\u0026eacute;d\u0026eacute;ration Internationale du B\u0026eacute;ton, Lausanne, Switzerland\u003c/em\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBisby LA, Green MF, Kodur VKR (2005) Response to fire of concrete structures that incorporate FRP. Prog Struct Mat Eng 7(3):136\u0026ndash;149. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1002/pse.198\u003c/span\u003e\u003cspan address=\"10.1002/pse.198\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCSA S806 (2002) Design and construction of building components with fibre-reinforced polymers. Can Stand Association\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRosa IC, Firmo JP, Correia JR (2022) Experimental study of the tensile behaviour of GFRP reinforcing bars at elevated temperatures. Constr Build Mater 324:126676. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.conbuildmat.2022.126676\u003c/span\u003e\u003cspan address=\"10.1016/j.conbuildmat.2022.126676\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang YC, Wong PMH, Kodur V (2007) An experimental study of the mechanical properties of fibre reinforced polymer (FRP) and steel reinforcing bars at elevated temperatures. Compos Struct 80(1):131\u0026ndash;140. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.compstruct.2006.04.069\u003c/span\u003e\u003cspan address=\"10.1016/j.compstruct.2006.04.069\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAbbasi A, Hogg PJ (2005) A model for predicting the properties of the constituents of a glass fibre rebar reinforced concrete beam at elevated temperatures simulating a fire test. Compos B Eng 36(5):384\u0026ndash;393. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.compositesb.2005.01.005\u003c/span\u003e\u003cspan address=\"10.1016/j.compositesb.2005.01.005\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNigro E, Cefarelli G, Bilotta A, Manfredi G, Cosenza E (2011) Fire resistance of concrete slabs reinforced with FRP bars. Part I: Experimental investigations on the mechanical behavior. Compos B Eng 42(6):1739\u0026ndash;1750. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.compositesb.2011.02.025\u003c/span\u003e\u003cspan address=\"10.1016/j.compositesb.2011.02.025\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKatz A, Berman N, Bank LC (1999) Effect of high temperature on bond strength of FRP rebars, \u003cem\u003eJournal of Composites for Construction\u003c/em\u003e, vol. 3, no. 2, pp. 73\u0026ndash;81, doi: 10.1061/(ASCE)1090-0268(1999)3:2(73)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBakis CE (1993) FRP Reinforcement: Materials and Manufacturing. Fiber-Reinforced-Plastic (FRP) Reinforcement for Concrete Structures. Elsevier, A. NANNI, Ed., Oxford, pp 13\u0026ndash;58. doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/B978-0-444-89689-6.50006-9\u003c/span\u003e\u003cspan address=\"10.1016/B978-0-444-89689-6.50006-9\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCalvet V, Valcuende M, Benlloch J, C\u0026aacute;noves J (2015) Influence of moderate temperatures on the bond between carbon fibre reinforced polymer bars (CFRP) and concrete. Constr Build Mater 94:589\u0026ndash;604. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.conbuildmat.2015.07.053\u003c/span\u003e\u003cspan address=\"10.1016/j.conbuildmat.2015.07.053\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSolyom S, Di Benedetti M, Guadagnini M, Bal\u0026aacute;zs GL (2020) Effect of temperature on the bond behaviour of GFRP bars in concrete. Compos B Eng 183:107602. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.compositesb.2019.107602\u003c/span\u003e\u003cspan address=\"10.1016/j.compositesb.2019.107602\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBanerji S, Kodur V (Apr. 2023) Numerical model for tracing the response of Ultra-High performance concrete beams exposed to fire. Fire Mater 47(3):322\u0026ndash;340. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1002/fam.3099\u003c/span\u003e\u003cspan address=\"10.1002/fam.3099\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eISO 834 (1999) \u003cem\u003eGeneva\u003c/em\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBolina F, Tutikian B, Rodrigues JPC (2021) Thermal analysis of steel decking concrete slabs in case of fire. Fire Saf J 121:103295. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.firesaf.2021.103295\u003c/span\u003e\u003cspan address=\"10.1016/j.firesaf.2021.103295\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBolina FL, Schallenberger M, Carvalho H (2023) Experimental and numerical evaluation of RC ribbed slabs in fire conditions, \u003cem\u003eStructures\u003c/em\u003e, vol. 51, pp. 747\u0026ndash;759, \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.istruc.2023.03.057\u003c/span\u003e\u003cspan address=\"10.1016/j.istruc.2023.03.057\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBolina FL, Poleto G, Carvalho H (2023) Proposition of parametric data for UHPC at high temperatures. J Building Eng 76:107222. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jobe.2023.107222\u003c/span\u003e\u003cspan address=\"10.1016/j.jobe.2023.107222\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBolina FL, Rodrigues JPC (2023) Finite element analysis criteria for composite steel decking concrete slabs subjected to fire. Fire Saf J 139:103818. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.firesaf.2023.103818\u003c/span\u003e\u003cspan address=\"10.1016/j.firesaf.2023.103818\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKodur VKR, Phan L (2007) Critical factors governing the fire performance of high strength concrete systems. Fire Saf J 42:6\u0026ndash;7. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.firesaf.2006.10.006\u003c/span\u003e\u003cspan address=\"10.1016/j.firesaf.2006.10.006\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"journal-of-building-pathology-and-rehabilitation","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bpar","sideBox":"Learn more about [Journal of Building Pathology and Rehabilitation](http://link.springer.com/journal/41024)","snPcode":"41024","submissionUrl":"https://submission.nature.com/new-submission/41024/3","title":"Journal of Building Pathology and Rehabilitation","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"GFRP, Glass Fiber rebars, Glass Fiber Reinforcements, Glass Fiber Reinforced Concrete, Structures in fire","lastPublishedDoi":"10.21203/rs.3.rs-5000212/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5000212/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eGFRP (glass fiber reinforced polymers) rebars can be used in RC (reinforced concrete) structures as an alternative to conventional steel rebars. Their application offers advantages, especially in chemically aggressive environments, as they can reduce the C (concrete cover) thickness required and also optimize the cross-sectional dimensions of these structures as well as their durability and service life. However, based on FE (finite element) numerical analysis solved by Abaqus software, this research has shown that the reduction in C-thickness promotes a notorious incongruity: an improvement in the fire sensitivity of these structures. The time in which GFRP-RC structures failed in fire can be around 400% lower in relation to identical conventional steel RC structures. In some cases, the fire resistance rate (FRR) of GFRP RC structures can be less than 10 min when the critical temperature of these rebars (around 100\u0026deg;C) is taken into account. The interest in structural durability criteria is not sufficient to justify the application of this new type of reinforcement in some concrete buildings.\u003c/p\u003e","manuscriptTitle":"The fire performance of GFRP-RC beams based on FE thermal analysis","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-10-21 10:46:01","doi":"10.21203/rs.3.rs-5000212/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-10-07T20:43:52+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-10-07T15:29:53+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-10-04T05:17:43+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"115293400099316465708208413297267216504","date":"2024-09-22T13:29:27+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"218106974961949079941799476805853717040","date":"2024-09-20T05:04:42+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-09-03T10:40:58+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-09-03T10:40:04+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-09-02T20:29:17+00:00","index":"","fulltext":""},{"type":"submitted","content":"Journal of Building Pathology and Rehabilitation","date":"2024-08-29T23:52:39+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"journal-of-building-pathology-and-rehabilitation","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bpar","sideBox":"Learn more about [Journal of Building Pathology and Rehabilitation](http://link.springer.com/journal/41024)","snPcode":"41024","submissionUrl":"https://submission.nature.com/new-submission/41024/3","title":"Journal of Building Pathology and Rehabilitation","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"0082a328-919a-4cb8-b367-06cf80c73ce3","owner":[],"postedDate":"October 21st, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2024-10-28T15:59:40+00:00","versionOfRecord":{"articleIdentity":"rs-5000212","link":"https://doi.org/10.1007/s41024-024-00530-3","journal":{"identity":"journal-of-building-pathology-and-rehabilitation","isVorOnly":false,"title":"Journal of Building Pathology and Rehabilitation"},"publishedOn":"2024-10-26 15:57:12","publishedOnDateReadable":"October 26th, 2024"},"versionCreatedAt":"2024-10-21 10:46:01","video":"","vorDoi":"10.1007/s41024-024-00530-3","vorDoiUrl":"https://doi.org/10.1007/s41024-024-00530-3","workflowStages":[]},"version":"v1","identity":"rs-5000212","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5000212","identity":"rs-5000212","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}