Analysis of Prestressed Concrete Pipe under Combined Loads

Abstract

A method based on a multi‐layered ring model of prestressed concrete pipe is presented for analysis of such pipe under the combined effects of internal fluid pressure, external load, and pipe and fluid weights. This method considers the nonlinear properties of the concrete core, mortar coating, prestressing steel wire, and steel cylinder. In particular, it accounts for tensile strain softening and cracking of core concrete and coating mortar, and the redistribution of moment that results from the changes of stiffness around the pipe. The combined loads corresponding to certain serviceability, elastic, and strength limit states are calculated. The calculated combined loads at the onset of visible core and coating cracks are compared to the results of tests conducted on six embedded‐ and lined‐cylinder pipes. The comparison shows good agreement. Significant moment redistribution from invert and crown to springline is shown to occur at combined loads that result in softening of core concrete at the invert and crown of the pipe.