Seismic Evaluation of Sweeping Bends

Abstract

This paper presents the results of analysis and evaluation of the seismic soil strains resulting from wave propagation or permanent ground deformation on sweeping bends in buried pipelines with bell and spigot joints. A finite element analysis of the sweeping bend with pipe-soil interaction is used to compute conservative axial forces and bending moments in the pipeline. The bell and spigot joint have limited capability to transmit moments resulting from compression waves. Stability of the joint exists when eccentricity caused by the moment is less than the outer radius of the pipe and the compressive stresses are not high enough to cause crushing of concrete. This instability of the pipe joints and the crushing of the concrete at the pipe joints are checked by evaluating the combined effects of the axial force and bending moment at critical sections of the pipeline. This method can also be used to analyze the effects of soil strains resulting from transient ground motion or permanent ground deformation occurring simultaneously with internal pressure and temperature load.