Seismic-Resistant Pipeline Design: Parametric Study of Axial Connection Force Capacity

This study focuses on the development of a pipeline performance classification for Axial Connection Force Capacity (CFC) to support the ongoing efforts of developing seismic design guidelines for water and wastewater systems. The only existing seismic design standard that includes a performance classification system for pipelines is ISO 16134. While this standard recommends performance, levels based on axial CFC (referred to as joint “slip-out resistance” under axial tension loading), it only considers ductile iron (DI) pipe and does not apply to other common pipe materials, connection types, or system components. Previous studies have defined the axial CFC of segmented PVCO (molecularly oriented polyvinyl chloride) pipes relative to Earthquake-Resistant DI Pipe (ERDIP) systems that have performed well during past seismic events and associated earthquake-induced permanent ground deformations. This study expands on previous work by adapting the ISO 16134 classification system for quantifying the CFC to additional pipeline materials and connections common to water distribution and wastewater collection systems. These pipeline materials and their system characteristics, such as joint/connection geometry, burial depth, and backfill soil conditions, affect seismic demands and deformations by influencing the frictional resistance along the pipe length and joint/connection as it undergoes axial deformations. This study quantifies a ratio between the CFC of a particular system of interest and the ISO ERDIP CFC, defined as K₁. The study demonstrates how this conversion factor, calculated based on analytical and experimental results, can be used to classify a pipeline systems’ CFC performance class. The enclosed evaluation of the frictional forces generated under significant ground movement (seismic demand), and the CFC required for a particular system to accommodate these various levels of potential demand, is intended to support industry guidelines for the seismic design of buried water and wastewater pipeline systems.