Experimental Assessment of Pipeline Connection Response to Transverse Loading

Buried pipelines are susceptible to damage from large ground displacements imposed by natural hazards such as earthquake-induced fault rupture, landslides, and liquefaction-induced settlements and laterals spreads. A significant percentage of water and wastewater networks are composed of segmented pipelines that are particularly vulnerable at the connections linking adjacent lengths of pipe. To address susceptibility to ground movement, new pipeline systems, with improved materials and jointing mechanisms, have been introduced into the market, some of which have had their seismic performance assessed through full-scale testing. This paper provides a framework for the interpretation of results from full-scale experiments designed to evaluate the transverse response of pipelines and connections under lateral loading. A series of four-point bending tests on thermoplastic pipelines with various connection types are discussed to illustrate lateral response mechanisms of traditional continuous and segmented systems, as well as pipeline connections that exhibit combined behavior. Displacement and strain measurements that capture simulated pipeline response to ground movement perpendicular to the pipe axis are employed to calculate key response metrics, namely joint deflection, pipe curvature, radius of curvature, and applied moment. The presented procedures provide guidance for characterizing transverse response relative to the seismic classification currently under develop in the ASCE/UESI manual of practice (MOP) on seismic design of water and wastewater pipelines. Procedures for interpreting experimental results and the implications for seismic design are discussed.