FLEXURAL CAPACITY OF PRESSURIZED STEEL PIPE

This paper describes the experimental and theoretical behavior of two large-scale pressurized pipes tested with a sleeve fully welded to the midspan of each specimen. Each specimen was subjected to an internal pressure, a constant axial load and lateral deformation of a four-poin t bend test to simulate the flexural behavior of a buried pipeline. Th e only test parameter was the length of the sleeve needed for pipe rep air; one specimen had a sleeve length equal to one pipe diameter, and the second specimen had a sleeve that was two pipe diameters in length . Flexural deformations were imposed on each test specimen until clear failure occurred. For both specimens, failure occurred by local wall buckling of the carrier pipe adjacent to the sleeve region. A simple t heoretical model is discussed to predict the flexural capacity of pipe s subjected to these load conditions. This analytical method was devel oped to enable a quick computation of the inelastic flexural strength of the pipe, and to enable a check of the output from a more sophistic ated finite element analysis. Reasonably good agreement was found betw een the theoretical and the experimental flexural capacity of the pres surized pipe. Analytical results demonstrated that the Tresca yield cr iterion conservatively estimated the inelastic flexural strength of th e pressurized pipe. It was also found that, when using the Tresca crit erion to describe the inelastic behavior of the pipes tested in this r esearch program, local inelastic wall buckling was initiated at a disp lacement ductility of about 3.