The Experimental Studies on Behavior of Ultrahigh-Performance Concrete Confined by Hybrid Fiber-Reinforced Polymer Tubes

This paper conducts axial compression test of ultrahigh performance concrete- (UHPC-) filled hybrid FRP (HFRP) tubes, using the alternating hybrid technology to improve the deformation capacity of FRP tube and measure the axial compressive responses of ultimate strength, strains, and stress-strain curve of confined specimens. The test results show that the local rupture of HFRP tubes did not lead to explosive failure of UHPC cylinder, and its ductility is better than that of UHPC confined by only one type of FRP tube; HFRP tube can effectively improve the compressive strength and ultimate strain of UHPC specimens; the stress-strain curves divide into three distinct regions: linear phase, transition phase, and linear strengthening phase. None of the models provided a reasonable prediction for strength and strain of HFRP-confined UHPC specimen; therefore, a new ultimate strength and strain perdition model considering the confinement effectiveness of different hybrid FRP series was proposed. The new proposed model presented the best fitting results. The stress-strain responses predicted by the existing models are all below the experimental curves; therefore, a new three-stage constitutive model was proposed, which relatively fits the test curves better than the existing models.

The Simulation Analysis of Tension Leveling for Improving the Shape Defects of Strip

According to the computation model of the stress, the strain, and the extend ratio in tension leveling, under the platform of mat lab, take the linear strengthening ball plastic model as the foundation, established the simulated program of the quantitative parameters enactment of tension leveling craft, this procedure consideration initial remaining stress of strip, namely random shape defects, assign tensile stress and the curving curvature, compute the strip’s stress and strain change and elongation ratio after tension leveling, given the stress and strain and the extension rate of the main process parameters from the simulation results of each roller, analysis of different process parameters set on impact of the simulation results, and the results conform to reality tension leveling production.