Abstract
The concrete-filled double skin steel tube (CFDST) is a more viable option compared to a concrete-filled steel tube (CFST) due to consisting a hollow section, while degradation is enhanced simply by using carbon fiber-reinforced polymer (CFRP). Hence, the stabilization of a concrete’s ductile strength needs high- performance fiber-reinforced cementitious conmposite. This study investigates the behavior of high-performance fiber-reinforced cementitious composite-filled double-skin steel tube (HPCFDST) beams strengthened longitudinally with various layers, lengths, and configurtion of CFRP sheets. The findings showed that, with increased CFRP layers, the moment capacity and flexural stiffness values of the retrofitted HPCFDST beams have significantly improved. For an instant, the moment capacity of HPCFDST beams improved by approximately 28.5% and 32.6% when they were wrapped partially along 100% with two and three layers, respectively, compared to the control beam. Moreover, the moment capacity of the HPCFDST beam using two partial layers of CFRP along 75% of its sufficient length was closed to the findings of the beam with two full CFRP layers. For energy absorption, the results showed a vast disparity. Only the two layers with a 100% full length and partial wrapping showed increasing performance over the control. Furthermore, the typical failure mode of HPCFDST beams was observed to be local buckling at the top surface near the point of loading and CFRP rapture at the bottom of effect length.
Highlights
Concrete-filled steel tubes (CFST) are known as structural composite members, wherein the voids of steel tubes are filled with concrete to enhance stiffness and load-bearing capacity [1]
The Mue ratio reached by the retrofitted sample to maximum control sample capacity was used to calculate the load improvement ratio (LIR)
This study presents the flexural behavior of double-skin steel tube beams filled with fiber-reinforced cementitious composite and strengthened with carbon fiber-reinforced polymer (CFRP) sheets
Summary
Concrete-filled steel tubes (CFST) are known as structural composite members, wherein the voids of steel tubes are filled with concrete to enhance stiffness and load-bearing capacity [1]. The inherent engineering properties of such materials have earned them the global application as a state-of-the-art. Materials 2020, 13, 3064 technique in the construction industry [2,3]. In such a design pattern, structural members are combined, such as the case in concrete-filled steel tubes, to provide unprecedented structural properties as solutions to a focused situation [1]. Concrete-filled steel tubes have numerous benefits, several advantages over ordinary structural steel, and normal reinforced concrete applications. The infill of concrete is restrained by the steel tube, resulting in producing a tri-axial limit state of compression that upsurges, which causes a hike in the strain and strength capacities of the infill of concrete [4]
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