Longitudinal Stresses and Strains in Design of RPM Pipes

Abstract

Pipelines are subjected to variable support conditions in the longitudinal direction. These support conditions are encountered due to the variation in bedding and soil properties along the pipe, the geometry of the pipeline, and the different installation schemes. Pipelines are also subjected to a variety of load combinations in the longitudinal direction. A study of these loads and support conditions and their effect on the performance of reinforced plastic mortar (RPM) pipe is made. A structural model used to calculate the longitudinal stresses on the pipe wall is presented. Composite laminate analyses are performed on RPM pipe wall with stress resultants from different load combinations. It is found that the allowable strains are exceeded when the pipe wall is analyzed as a composite structure. In some installation conditions, the strains in the longitudinal direction prove to be more critical than the strains in the circumferential direction. It is recognized that the design of the fiberglass reinforcement in the circumferential and longitudinal directions and the fabrication of wall laminas could be improved if an elaborate analysis procedure, like the one proposed in this study, is adopted.