Shear capacity of unbonded post-tensioned concrete T-beams strengthened with CFRP and GFRP U-wraps

Abstract

Existing codes and design guidelines have not mentioned a procedure to calculate the shear resistance of unbonded post-tensioned concrete beams strengthened with fiber reinforced polymer (FRP) sheets. Up to date, the number of studies about the shear behaviour of posttensioned concrete beams strengthened with FRP sheets in shear is very limited, particularly for unbonded post-tensioned beams. The effect of many factors on the shear resistance of such the beams has not been well investigated, for example, fiber factors (the type of fiber, the strengthening scheme, and the number of layers), the concrete strength, and the ratio of the shear span to effective depth. The study deals with the shear behaviour of unbonded posttensioned beams strengthened with FRP U-wraps. The experiment consists of twenty-two post-tensioned beams with T section and unbonded tendons. The variables include concrete strength, number of FRP layers, FRP U-wraps scheme (continuous and spaced), types of FRP, and varied shear span to effective depth. The experimental results have shown that the FRP

Effect of fiber amount and stirrup ratio on shear resistance of steel fiber reinforced concrete deep beams

“…The beams were tested by using a 1000 kN capacity hydraulic testing machine using a load-manipulated regime. The loading increment was 10 kN up to failure, which equals the loading rate of 15 kN per minute as per the previous studies [9,15]. At each loading increment, the beam's displacement, strains of concrete and rebars, and crack development and propagation were recorded.…”

“…However, for shorter span beams, particularly deep beams, due to their geometry, the shear behavior plays a decisive role. In these beams, the shear cracks may form in the web due to high diagonal tensile stress and precipitate failure before the ultimate flexural capacity of the beam is reached [8,9].…”

Shear resistant capacity of steel fibres reinforced concrete deep beams: An experimental investigation and a new prediction model

“…shear governs the behaviour of deep beams [11]. For example, shear cracks usually appear in the web of a deep beam because of high inclined tensile stresses in this zone, which cause the beam to fail before reaching its moment capacity [12][13][14][15]. An effective method to increase shear resistance of a structure element is to use steel fibres.…”

Distinguished punching shear behaviour of unbonded post-tensioned concrete slab – CFT column vs reinforced concrete slab – CFT column connections

“…In this study, the concrete mix design consisted of Portland cement PC40 (460 kg/m 3 ), 20-22 mm coarse aggregates (1048 kg/m 3 ), 2-4 mm river sand (640 kg/m 3 ) and clean water (194 l/m 3 ). The slump of the concrete 12 ± 2 cm, which is a typical range for casting structural members [23,24,26]. The compressive strength of concrete ( f c ) was derived from the mean values of three 150×300 mm concrete cylinders according to TCVN 10303:2014 [27].…”

“…The punching shear response of RC slab -CFT column connections has been well investigated in many studies [1,4,5,[14][15][16][17][18][19][20][21][22]; however, the research effort toward PC slab -CFT column connections is still very limited [7]. It is noteworthy that the prestressing force can embrittle the behaviour and reduce the ductility and energy absorption capacity of PC members [12,[23][24][25]. Therefore, the punching shear performance of the PC slab -CFT column connection, especially the difference in the structural response with the RC slab -CFT column connection, deserves careful investigation.…”