The cross-section and reinforcement situation of specimens are shown in Figure 1.
The longitudinal rebar and stirrup were HRB400 and HRB335, respectively, with the ratio of 2.543% and 1.273%, respectively. The size of the fixed end was 900 × 220 × 360 mm, where the horizontal longitudinal bar was 14 mm HRB400 (hot-rolled ribbed bars, and the standard value of the yield strength of the steel bar is 400 MPa), and the stirrup was 8 mm HRB335 with spacing of 50 mm. The size of the loading end was 200 × 300 × 400 mm, which was embedded with four M24 high-strength bolts for connection with the actuator. The cross-section of the test section was 200 × 200 mm with the height of 300 mm. PVC, polyvinyl chloride CST, circle steel tube RHC, reinforced high-strength concrete.Īll specimens have the same external dimensions. Note: L represents the height of test specimens h and b are the sectional height and width of column cross section, respectively λ is the shear span ratio n is the axial compression ratio. It is expected to provide new technical support for the further promotion and application of high-strength concrete. In order to reveal its failure mechanism and seismic performance, the low-cyclic loading test of the PVC-RHC is carried out. However, the relevant research of the PVC-RHC has not been reported in the literature at present. Patel VI performed a parametric analysis of fiber-based models to examine the effects of local buckling, bending axis, aspect ratio, and material strength on uniaxial compression RCFST (Round-ended concrete-filled steel tubular) short beam-columns’ performance. At the same time, the confinement mechanism of concrete-filled steel tubular columns should be discussed. Other researchers found that PVC pipe confined concrete mostly appears plastically damaged, which improves the bearing capacity, seismic deformation, and durability of specimens with less cost, energy saving, and environmental protection. H.Toutanji systematically studied the mechanical properties, durability, and design methods of grooved PVC-FRP (Fiber Reinforced Polymer) pipe concrete short columns. It is proposed that the PVC plastic pipe confined concrete column can be applied to engineering. Through the axial compression test of a PVC plastic pipe confined concrete column, C.E.Kurt found that the PVC plastic pipe improved the mechanical properties of core concrete by providing a constraining force. Large relevant universities and research institutes have also carried out some tests on PVC pipe-constrained concrete. On the basis of the theory of a concrete-filled steel tube, a new type of confined high-strength concrete column embedded with polyvinyl chloride pipe (PVC-RHC) is proposed, which is intended to reduce the density of the stirrup and ensure good ductility by the confined effect of the PVC pipe to core concrete. Therefore, it is necessary to seek more effective and economical ways. Usually, the volume–stirrup ratio is improved in order to increase the deformation capacity of RHC, which also leads to the construction difficulties, the increased use of steel and high cost of projects. However, with the increase of concrete strength, the frangibility increases and plastic deformation ability decreases. Owing to the advantages of high strength, little deformation, and good durability, reinforced high-strength concrete (RHC) is widely used in long-span, heavy-duty, and high-rise buildings. Thus, according to the failure mechanism of the PVC-RHC specimen, a new calculation formula of shear bearing capacity is deduced, which is in good agreement with the experimental results. The shear bearing capacity of the PVC-RHC specimen calculated with “concrete structure design code” (GB 50010-2010) was smaller than the test results by 25%, showing an excessive safety margin.
With the increase of the diameter–length ratio and axial pressure, the energy dissipation capacity and deformation capacity of PVC-RHC specimens decreased. Compared with RHC specimens, the hysteretic curves of the PVC-RHC specimen and CST-RHC specimen were fuller furthermore, their energy dissipation capacity, deformation, and ductility were more beneficial. The research results indicate thhe following: all specimens displayed shear baroclinic failure.
The influences of PVC pipe diameter, axial compression ratio, and concrete strength on seismic performance indexes are analyzed. The failure mechanism and morphology are revealed by experiments. To study the seismic performance of embedded polyvinyl chloride (PVC) pipe confined reinforced high-strength concrete (PVC-RHC) columns, five specimens are designed for cyclic loading test, which include three PVC-RHC column specimens, an embedded circle steel tube confined reinforced high-strength concrete (CST-RHC) column specimen, and a reinforced high-strength concrete (RHC) column specimen.