Flexural Pseudo-Ductility Effect in Hybrid GFRP/CFRP Bars under Static Loading Conditions

Abstract

The problem with composite rebars in the civil engineering industry is often described as the material’s brittleness while overloaded. To overcome this drawback, researchers pay attention to the pseudo-ductility effect. The paper presents four-point bending tests of pure unidirectional (UD) rods with additional composite layers obtained by filament winding and hand braiding techniques. Two types of core materials, glass FRP (fibre reinforced polymer) and carbon FRP, were used. Regarding the overwrapping material, the filament winding technique utilized carbon and glass roving reinforcement in the epoxy matrix, while in the case of hand braiding, the carbon fibre sleeve was applied with the epoxy matrix. Microstructural analysis using scanning electron microscopy (SEM) and computed tomography (CT) was performed to reveal the structural differences between the two proposed methods. Mechanical test results showed good material behaviour exhibiting the pseudo-ductility effect after the point of maximum force. The two applied overwrapping techniques had different influences on the pseudo-ductility effect. Microstructural investigation revealed differences between the groups of specimens that partially explain their different characters during mechanical testing.

Investigation of flexural behaviour of composite rebars for concrete reinforcement with experimental, numerical and machine learning approaches

“…It can be noticed in figure 10 that gradual failure occurs. In the literature, it is described as a pseudo-ductile effect [43]. This effect is caused by the various stiffnesses of materials that leads to a different stress state in each material.…”

Numerical Simulation of the Bearing Capacity of Variotropic Short Concrete Beams Reinforced with Polymer Composite Reinforcing Bars

“…Of course, such tasks should be approached in a comprehensive manner, and building elements made of heavy concrete with various reinforcing elements should be evaluated as a system operating in conditions of a certain synergy [ 24 , 25 , 26 , 27 , 28 , 29 ]. Such synergy, as we have already established earlier, can be complex reinforcement, namely, fiber plus reinforcing bars, improved concrete characteristics due to their nanomodification or the same fiber reinforcement with fibers [ 30 , 31 , 32 , 33 , 34 ]. However, in addition to the above methods, it is also promising to create so-called differentiated building elements, particularly in their cross section [ 35 , 36 , 37 , 38 , 39 , 40 ].…”

“…Mineral impregnated carbon fiber composites are a new type of reinforcement for construction. Compared to steel reinforcement, carbon fiber reinforcement has a much higher tensile strength and a significantly lower weight [ 22 , 24 , 31 , 33 , 35 , 38 , 39 , 41 , 42 , 43 , 44 , 47 , 49 , 51 , 55 , 59 ]. At present, the technology of reinforcing concrete bending elements with carbon fiber sheets is popular [ 44 , 59 ].…”

The Effect of Flame Retardant—Aluminum Trihydroxide on Mixed Mode I/II Fracture Toughness of Epoxy Resin

“…Referring to composite materials, several manufacturing technologies can be highlighted, such as hand laminating, vacuum bagging [ 4 ], infusion [ 5 ], pultrusion [ 6 , 7 ], and filament winding [ 8 , 9 , 10 , 11 ]. Those processes allow manufacturers to provide the very complex material geometries and structures used in many modern applications.…”