ISSN 1520-295X Seismic Response Modeling of Water Supply Systems by Peixin Shi and Thomas D. O’Rourke Technical Report MCEER-08-0016 May 5, 2008 This research was conducted at Cornell Universityand was supported primarily by the Earthquake Engineering Research Centers Program of the National Science Foundation under award number EEC 9701471. NOTICE This report was prepared by Cornell University as a result of research spon- sored by MCEER through a grant from the Earthquake Engineering Research Centers Program of the National Science Foundation under NSF award number EEC-9701471 and other sponsors. Neither MCEER, associates of MCEER, its sponsors, Cornell University, nor any person acting on their behalf: a. makes any warranty, express or implied, with respect to the use of any information, apparatus, method, or process disclosed in this report or that such use may not infringe upon privately owned rights; or b. assumes any liabilities of whatsoever kind with respect to the use of, or the damage resulting from the use of, any information, apparatus, method, or process disclosed in this report. Any opinions, findings, and conclusions or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the views of MCEER, the National Science Foundation, or other sponsors. Seismic Response Modeling of Water Supply Systems by Peixin Shi1 and Thomas D. O’Rourke2 Publication Date: May 5, 2008 Submittal Date: March 28, 2008 Technical Report MCEER-08-0016 Task Number 10.1.2 NSF Master Contract Number EEC 9701471 1 Geotechnical Engineer, PB Americas, Inc., Geotechnical and Tunneling Group; for- mer Ph.D. Candidate, School of Civil and Environmental Engineering, Cornell Uni- versity 2 Thomas R. Briggs Professor of Engineering, School of Civil and Environmental Engi- neering, Cornell University MCEER University at Buffalo, The State University of New York Red Jacket Quadrangle, Buffalo, NY 14261 Phone: (716) 645-3391; Fax (716) 645-3399 E-mail: [email protected]; WWW Site: http://mceer.buffalo.edu Preface The Multidisciplinary Center for Earthquake Engineering Research (MCEER) is a national center of excellence in advanced technology applications that is dedicated to the reduction of earthquake losses nationwide. Headquartered at the University at Buffalo, State University of New York, the Center was originally established by the National Science Foundation in 1986, as the National Center for Earthquake Engineering Research (NCEER). Comprising a consortium of researchers from numerous disciplines and institutions throughout the United States, the Center’s mission is to reduce earthquake losses through research and the application of advanced technologies that improve engineering, pre- earthquake planning and post-earthquake recovery strategies. Toward this end, the Cen- ter coordinates a nationwide program of multidisciplinary team research, education and outreach activities. MCEER’s research is conducted under the sponsorship of two major federal agencies: the National Science Foundation (NSF) and the Federal Highway Administration (FHWA), and the State of New York. Signifi cant support is derived from the Federal Emergency Management Agency (FEMA), other state governments, academic institutions, foreign governments and private industry. MCEER’s NSF-sponsored research objectives are twofold: to increase resilience by devel- oping seismic evaluation and rehabilitation strategies for the post-disaster facilities and systems (hospitals, electrical and water lifelines, and bridges and highways) that society expects to be operational following an earthquake; and to further enhance resilience by developing improved emergency management capabilities to ensure an effective response and recovery following the earthquake (see the fi gure below). Earthquake Resilient Communities Through Applications of Advanced Technologies Infrastructures that Must be Available / Intelligent Response Operational following an Earthquake and Recovery Hospitals More Cost- Water, Gas Pipelines Earthquake Effective Resilient Urban Retrofit Electric Power Infrastructure Strategies Network System Bridges and Highways iii A cross-program activity focuses on the establishment of an effective experimental and analytical network to facilitate the exchange of information between researchers located in various institutions across the country. These are complemented by, and integrated with, other MCEER activities in education, outreach, technology transfer, and industry partnerships. This report presents a comprehensive model for simulating the earthquake performance of water supply systems. The model is developed in conjunction with the water system operated by the Los Angeles Department of Water and Power (LADWP) and validated through comparisons to ob- servations and fl ow measurements for the heavily damaged LADWP water supply after the 1994 Northridge earthquake. The earthquake performance of damaged water supply systems is simulated using hydraulic network analysis that uses an iterative approach to isolate the network nodes with negative pressures. The isolation process accounts accurately for reliable fl ows and pressures in the damaged water networks by removing unreliable fl ows and identifying those portions of the system requiring mitigation. An analytical model is developed to predict the effect of seismic waves on underground pipelines. The seismic performance of the LADWP system is simulated using a multi- scale technique in which the LADWP trunk system is explicitly accounted for, while the remaining distribution lines are simulated through fragility curves relating demand to repair rate. The repair rate, in turn, is correlated with peak ground velocities, and fragility curves are developed on the basis of distribution network simulations. The proposed model is integrated into computer code, Graphical Iterative Response Analysis for Flow Following Earthquakes (GIRAFFE) developed by the authors, which presents the simulation results in GIS format. iv ABSTRACT This report describes a comprehensive model for simulating the earthquake performance of water supply systems. This model is developed in conjunction with the water supply system operated by the Los Angeles Department of Water and Power (LADWP) and validated by a favorable comparison of simulation results with observations and flow measurements for the heavily damaged LADWP water supply after the 1994 Northridge earthquake. Earthquake performance of water supply systems is simulated using hydraulic network analysis. Hydraulic simulation procedures for heavily damaged water supply systems are developed on the basis of an iterative approach to isolate the network nodes with negative pressures step by step, starting with the one of highest negative pressure. The isolation approach accounts accurately for reliable flows and pressures in the damaged system. The isolation approach removes unreliable flows, and identifies vulnerable parts of the damaged system for mitigation. To predict earthquake damage to underground water supply pipelines, an analytical model is developed for surface wave interaction with jointed concrete cylinder pipelines (JCCPs). A dimensionless chart is developed for estimating the joint pullout of JCCPs under the action of seismic waves. This model is applied to analyze seismic wave interaction with other jointed pipelines, such as cast iron (CI) pipelines with lead-caulked joints. Dimensionless reduction curves are developed for estimating joint pullout associated with brittle and ductile joint performance. Pipeline damage in hydraulic simulations is classified as breaks and leaks. A break is simulated by disconnecting the original pipeline completely and opening the broken ends into the atmosphere; a leak is simulated as an orifice in the pipe wall. Energy loss from the leak is accounted for as minor losses. Five different scenarios of leakage are simulated as a function of pipe diameter. v Seismic performance of the LADWP system is simulated using a multi-scale technique. This technique explicitly accounts for 2,200 km of pipelines, associated with the LADWP trunk system, and simulates the remaining 9,800 km of distribution lines by fragility curves relating demand to repair rate in the distribution network. Repair rate, in turn, is correlated with peak ground velocity. The fragility curves are developed on the basis of LADWP distribution network simulations. A computer code, GIRAFFE, is developed for the implementation of the model. GIRAFFE builds on an open source hydraulic network analysis engine, EPANET, and works in conjunction with Geographical Information Systems (GIS) for simulation result presentations. vi ACKNOWLEDGMENTS This research was funded by the Earthquake Engineering Research Centers Program of the National Science Foundation (NSF) through the Multidisciplinary Center for Earthquake Engineering Research (MCEER). The financial support from the NSF and MCEER is gratefully acknowledged. Thanks and acknowledgements are given to the Los Angeles Department of Water and Power (LADWP) engineers, namely Mr. Collins Anselmo, Mr. Craig Davis, Mr. Paul Gillis, Mr. Vargas Victor, and others whose names I might have inadvertently missed, for providing information on the LADWP water supply system, the 1994 Northridge earthquake trunk line damage, and the SCADA data. vii TABLE OF CONTENTS Chapter Title Page 1 INTRODUCTION ......................................................................... 1 1.1 Background .....................................................................................