FRP-confined concrete filled PVC tubes: A new design concept for ductile column construction in seismic regions

Abstract

In their recent work [1], authors have introduced and validated a new ductile design concept of confined concrete-filled polyvinyl-chloride tubular (CCFPT) columns through experimental and analytical studies. Confinement was provided with the use of a polyvinylchloride (PVC) tube and fiber-reinforced polymer (FRP) wrappings or FRP with a sandwiched layer of foam to enhance impact energy reduction due to potential FRP rupture and PVC fracture. In the present paper, additional flexural tests on CCFPT columns were undertaken to further investigate the structural behavior of the proposed system for column construction in seismic regions. Axial and flexural behavior of CCFPT columns was investigated with compressive and flexural tests, respectively, and compared with those of their corresponding concrete-filled polyvinyl-chloride tubular (CFPT) and FRP-wrapped (FW) columns. Test results obtained from 152×305 mm (6×12 in.) stub columns under axial loads and 152×1524 mm (6×60 in.) flexural beams under four-point loads indicated that the CCFPT columns can significantly enhance strength over the CFPT columns and enhance ductility over the FW columns. The transverse confining pressure from FRP wrapping and the interface property between the FRP and PVC proved critical in CCFPT design. Furthermore, the idea of introducing a cushioning foam layer between FRP layers and PVC to lessen the brittleness of FRP rupture in seismic regions proved effective.

Structural Performance of uPVC Confined Concrete Equivalent Cylinders Under Axial Compression Loads

“…Energy absorption is the toughness of the material, as measured from the stress-strain data. It is the area under a stress-strain curve and is measured using the expression that is given in Equation (9). On literature, energy absorption was reported in different ways depending on the strain value that was chosen to end the integration [15,40,[42][43][44].…”

“…Work is a total force required to shorten the uPVC confined cylinder under axial compression and it is stored as energy in the material. Energy stored in the material is the area under the stress-strain curve, as expressed in Equation (9) and Figure 20. The work index is calculated to show how the material undergoes straining for the applied load beyond the elastic state.…”

“…The durability of uPVC was investigated by dipping the uPVC specimen in acid, alkaline, and organic compounds for a time. The predicted service life shows that uPVC has the potential of retaining its integrity without deterioration for more than 50 years [1,2,[8][9][10]. Experimental investigations regarding damage initiation, stress deterioration, crack initiation and growth, impact tests, bursts, and the tensile and fatigue of PVC have exhibited remarkable performance, in that its service life may extend beyond 100 years [2,[11][12][13][14].…”

“…However, the use of uPVC pipes as a concrete confining material is at its very beginning and the amount of information on how to design and use it in construction is very limited. It has been established that providing a uPVC lateral confinement can enhance the strength and ductility of concrete [4][5][6]9,[17][18][19]. Gupta and Verma [8] investigated the durability through submerging the PVC confined RC column for six months into a salt concentration, which is more than 20 times more so than natural seawater.…”

Mechanical behaviour of PVC-CFRP confined concrete column with RC beam joint subjected to axial load

“…Fakharifar [17] analysed the effect of the type and thickness of FRP tube, compressible foam, and the loading zone, on the behaviour of PFCC. The experiment for the seismic resistance of PFCC was performed by Fakharifar [18], and high ultimate strength and good ductility of PFCC were demonstrated. Jiang [19] studied the influence of the axial force ratio, the layer and type of FRP on the circular section reinforced concrete composite column with FRP-PVC tube under cyclic loading.…”