An evaluation of seismic serviceability of water supply networks with application to the San Francisco auxiliary supply system

ABSTRACT

A nes method is presented for estimating a serviceability of water networks damaged during earthquakes. Several measures are developed for evaluating the serviceability. These seismic serviceability measures are random variables that depend on uncertain parameters such as seismic intensity, water supply, system damage state, and water demand. The determination of the proposed serviceability measures involves hydraulic analyses of water supply systems in various damage states. Commercially available softwares for hydraulic analysis are configured for intact networks and can not be used reliably for heavily damaged and leaking systems. A computer code is developed for the hydraulic analysis of damaged water supply systems. The code eliminates those portions of the network which have negative pressures, and predicts the available flow and pressure at the demand nodes. The hydraulic analysis also accounts for the dependence of C-factors, which represents internal pipe roughness, on the pipe diameter. This dependence is validated by fire flow tests perfomed in San Francisco. The code has capabilities of simulating a seismic network perfomance with the uncertain parameters. The serviceability measures and the proposed algorithm for hydraulic analysis are applied to evaluate the seismic serviceability of the Auxiliary Water Supply System in San Francisco. Numerical results of deterministic and stochastic parametric studies show that the algorithm for calculating serviceability measures is robust and efficient.(AU)