Tests conducted on buried high-density polyethylene pipes are reported. Pipes were loaded until buckling occurred to determine performance limits and the influence of profile parameters on structural performance. These profile parameters include rib height, rib spacing, wall thicknesses, wall area per unit length, unsupported profile section length, and stiffness. In a profile-wall pipe, by design, as much pipe material as possible is placed away from the neutral axis in the form of inside or outside walls or in ribs to minimize the use of pipe material by increasing the section modulus of the pipe wall. For the products tested, the data show that the profile section acts as a unit as designed only up to a point. High earth loads will induce buckling in the profile wall of the pipe. For adequate safety, the pipe design should include sufficient plastic between the inner and outer walls or between the ribs to carry shear and to ensure that the profile section indeed acts as a unit. Each product exhibits different performance limits, and these limits occur at different loads and deflections. Performance limits are often deflection related, but for high soil densities they are load related. For profile-wall pipe, localized or general buckling is usually the lowest performance limit. The cross-sectional area per unit length and the individual wall component thickness should be sufficient to resist localized buckling. It should be noted that for some profile-wall pipes, controlling vertical deflection may not control localized buckling as a performance limit. Performance limits for the pipes tested are reported.
Structural performance of poultry eggshell derived hydroxyapatite based high density polyethylene bio-composites
