1 Water Distribution System Reliability under a Fire Flow Condition: a Probabilistic Approach Julio Gomes 1 and Bryan W. Karney 2 1 Ph.D Candidate, IPH/UFRGS, CNPq-Brazil Scholarship. Professor, Department of Civil Engineering, Centro Universitário Positivo (UnicenP). Rua Prof. Viriato Parigot de Souza, 5300; Curitiba, 81280-330, Paraná, Brazil. PH (55)(41) 317-3256; FAX (55)(41) 317-3030; email: jgomes@unicenp.br 2 Ph.D, Professor, Department of Civil Engineering, University of Toronto. 35 St. George Street; Toronto, M5S 1A4, Ontario, Canada. PH (416) 978-7776; FAX (416) 978-3674; email : karney@civ.utoronto.ca Abstract In the technical literature concerned with the design of water distribution systems (WDS), the term ‘fire flow’ is often associated with three distinct challenges: to estimate the actual fire flow needed to fight a fire; to estimate the availability of fire flow in a specific WDS; or, to evaluate the potential impacts of fire flow on WDS reliability. The first two challenges are generally addressed from a deterministic perspective, and, although some probabilistic approaches exist for solving the latter one, they seldom address fire flows explicitly. In general, fire flows are considered as part of a unique nodal flow probability distribution for reliability analysis purposes. Yet one significant question remains consistently unanswered: what is the WDS reliability given that a fire situation occurs? The objective of this study is to present a methodology which can be used to evaluate the WDS reliability under a fire condition. To this end, two different probability distributions are assessed for the nodal flows: one representing the base demands and the other representing the fire flow demands. A Monte Carlo method is used to generate the flows, and steady-state hydraulic simulations are performed to derive both nodal and system reliability indexes for a WDS under a fire condition. Introduction Many communities base the design of water distribution mains on providing adequate water for fire protection. Such design practice is based on the fact that fire flow requirements sometimes exceed the normal domestic, industrial, and other demands imposed on the water system (Boulos et al., 1997). The effects of fire demands are difficult to derive precisely since fires occur with random frequency and intensity in different areas, with each area having unique fire protection requirements. In the technical literature concerned with the design of water distribution systems, the term ‘fire flow’ is often associated with three distinct challenges: to estimate the actual fire flow needed to fight a fire; to estimate the availability of fire flow in a specific water distribution system (WDS); or, to evaluate the potential Copyright ASCE 2005 EWRI 2005 Impacts of Global Climate Change Downloaded from ascelibrary.org by UNIVERSITY OF TORONTO on 07/21/14. Copyright ASCE. For personal use only; all rights reserved.