Static and Flexural Fatigue Behavior of GFRP Pultruded Rebars

Abstract

This paper presents the experimental results of composite rebars based on GFRP manufactured by a pultrusion system. The bending and radial compression strength of rods was determined. The elastic modulus of GFRP rebars is significantly lower than for steel rebars, while the static flexural properties are higher. The microstructure of the selected rebars was studied and discussed in light of the obtained results—failure processes such as the delamination and fibers fracture can be observed. The bending fatigue test was performed under a constant load amplitude sinusoidal waveform. All rebars were subjected to fatigue tests under the R = 0.1 condition. As a result, the S-N curve was obtained, and basic fatigue characteristics were determined. The fatigue mechanism of bar failure under bending was further analyzed using SEM microscopy. It is worth noting that the failure and fracture mechanism plays a crucial role as a material quality indicator in the manufacturing process. The main mechanism of failure under static and cyclic loading during the bending test is widely discussed in this paper. The results obtained from fatigue tests encourage further analysis. The diametral compression test reflects the weakest nature of the composite materials based on the interlaminar compressive strength. The proposed methodology allows us to invariantly describe the experimental transversal strength of the composite materials. Considering the expected durability of the structure, the failure mechanism is likely to significantly improve their fatigue behavior under the influence of cyclic bending. The reasonable direction of searching for reinforcements of composite structures should be the improvement of the bearing capacity of the outer layers. In comparison with steel rebars (fatigue tensile test), the obtained results for GFRP are comparable in the HCF regime. It is worth noting that in the near fatigue endurance regime (2–5 × 106 cycles) both rebars exhibit similar behavior.

Making a Case for Hybrid GFRP-Steel Reinforcement System in Concrete Beams: An Overview

“…Additionally, some studies [72,73] recommended carbon/glass fibre-reinforced polymer hybrid (HFRP) in critical applications such as oil wells and bridges to address these durability issues. However, while there may be concerns about the limitations of GFRPs on their long-term durability, there are pieces of evidence presented [74][75][76] that has highlighted GFRP advantages over steel rebars in tackling durability concerns in RC structures.…”

Wear Resistance of Selected Anti-Wear Coatings Used in Multi-Material Composite Hydraulic Cylinders

“…They are also widely used in transport, especially in the automotive, aviation and rail industries, allowing to reduce the weight of vehicles and thus reduce fuel demand and improve profitability (Banerjee et al, 2011;Mrazova, 2013). An important feature is that some composite materials are more resistant to fatigue loads during take-off or landing, which results in fewer checks during the operation of the aircraft (Barcikowski et al, 2021). The same expectation applies to all connections: steel and composite (Grzejda et al, 2021).…”

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“…This underscores the significance of material design for GFRP, emphasizing the selection of materials capable of withstanding such environmental degradation through thoughtful resin mix choices [19]. While concerns exist regarding the long-term durability of GFRPs, evidence presented in many studies [20][21][22][23] highlights the advantages of GFRP over steel rebars in mitigating durability issues in reinforced concrete structures.…”