Finite Element Analysis of Combined-Load Performance of PressureCast Steel Pipe

PressureCast Steel Pipe (PCSP) utilizes a patented manufacturing process to pre-compress the concrete (or mortar) lining in the steel pipe, thus making the liner less susceptible to cracking and substantially increasing the stiffness of the steel pipe. The increased stiffness of PCSP makes it potentially less expensive to install than ordinary steel pipe. This paper presents the results of a combined load test performed by Ameron on a buried PCSP in a soil box along with a finite element analysis of pipe loading to determine performance of PCSP when subjected to combined external loading and internal pressure. To simulate an extreme installation condition, the soil consisted of lightly compacted CL soil with high moisure content. The data was collected on pipe deflection and steel strains as well as on the extent of cracking of the concrete liner at different load and pressure combinations. The finite element model provides a linear elastic model of the soil box, a Mohr-Coulomb model of the plastic soil, and a nonlinear material model of the pipe. The nonlinear material model of the pipe includes representation of tensile softening and cracking of concrete, yielding of steel, and bond failure at concrete lining-to-steel cylinder interface due to radial tension or shear.