This paper presents the results of experimental studies on reinforced concrete columns strengthened with CFRP composites under combination of axial load and bending moment. A total of seven large-scale specimens with rectangular cross section (200 mm × 300 mm) were prepared and tested under eccentric compressive loading up to failure. The overall length of specimens with two haunched heads was 2700 mm. Different FRP thicknesses of 2, 3, and 5 layers, fiber orientation of 0 o , 45 o , and 90 o , and two eccentricities of 200 and 300 mm were investigated. The effects of these parameters on load-displacement and moment-curvature behavior of the columns as well as the variation of longitudinal and transverse strains on different faces of the columns were studied. The results of the study demonstrated significant enhancement on performance of strengthened columns compared to unstrengthened columns.
In this study, the flexural behavior of sandwich composite beams made of fiber-reinforced polymer (FRP) skins and light-weight cores are studied. The focus is on the comparison of natural and synthetic fiber and core materials. Two types of fiber materials, namely glass and flax fibers, as well as two types of core materials, namely polypropylene honeycomb and cork, are considered. A total of 105 small-scale sandwich beam specimens (50 mm wide) were prepared and tested under four-point bending. Test parameters were fiber types (flax and glass fibers), core materials (cork ad honeycomb), skin layers (0, 1, and 2 layers), core thicknesses (6–25 mm), and beam spans (150 and 300 mm). The load–deflection behavior, peak load, initial stiffness, and failure mode of the specimens are evaluated. Moreover, the flexural stiffness, shear rigidity, and core shear modulus of the sandwich composites are computed based on the test results of the two spans. An analytical model is also implemented to compute the flexural stiffness, core shear strength, and skin normal stress of the sandwich composites. Overall, the natural fiber and cork materials showed a promising and comparable structural performance with their synthetic counterparts.
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