Seismic Design Approach for Ductile Iron Pipe Including Alternative to Boltless Segment Joints

Seismic joint performance for ductile iron pipe (DIP) products has seen significant advancements in recent years across the industry. Procedures to establish the minimum required DIP seismic joint performance requirements are lacking in the industry. This paper describes an approach to establish minimum seismic joint performance requirements based on procedures developed as part of the $1.6 billion Willamette Supply Program (WWSP, Program). The WWSP includes over 30 mi of large diameter water transmission line in the seismically active Pacific Northwest region which is at risk of a magnitude 9.0 Cascadia Subduction Zone earthquake. For the Program, boltless segment joint DIP was identified as the required type of DIP joint. Complicating factors related to delivery schedules, supply chain issues, and the need for field flexibility during installation, however, made the use of boltless segment jointed DIP infeasible in some cases. To address this, the Program developed new alternative procedures to utilize lower strength, but more available products without compromising its high seismic performance standards. This paper describes these new procedures established related to alternatives to exclusive use of boltless segment jointed DIP.