Damage to water pipes during the 1994 Northridge earthquake

This paper presents damage to pipes of a water supply network system under the control of the Department of Water and Power of City of Los Angels(LADWP). Site investigation was conducted at San Fernando Valley where the damage to trunk lines, distribution pipes and service pipes were concentrated. Sixteen breaks of large diameter trunk lines and approximately 1.670 breaks of small diameter distribution pipes and service pipes were damaged during the earthquake. The damage to the trunk lines contains breaks of joints and pipes of an oldriveted trunk line buried along Roscoe Street, which breaks were occurred just over or very close to the epicenter. Other typical damage to the trunk lines were telescopic crashes and failures in tension of welded bell joints due to slight permanent ground movement at Balboa Boulevard. Most of the breaks of small diameter distribution pipes were caused to old and weak gray cast iron pipes connected with sockets and spigot joints, whose flexibility or strength against dynamic and permanent ground movement could not be expected. And the breaks include those of the service pipes were concentrated in Northridge district including Granada hills, San Fernando district and Sherman Oaks district.(AU)

An overview of seismic design of buried lifeline structures in Japan

The purpose of this paper is to give an overview of eight major seismic design codes for underground lifeline structures in Japan, which are currently applied to pipelines, common utility ducts, power cable ducts and other lifeline facilities. The history and outlines of the design codes are summarized in the paper. The seismic design codes are divided into two groups, one of which is based on the theory of seismic wave propagation and the other takes permanent ground deformation or a liquefaction-induced uplift force into consideration. Of the eight seismic esign codes, six including the Technical Standard for Oil Pipelines (1974) are classified in the former and four including the Specifications for Seismic Design of Medium and Low Pressure Gas Pipelines (1982) are in the latter group. Also presented in the paper is comparison of methodologies to estimate ground responses, wavelengths, modeling of the permanent ground deformation, soil spring characteristics, the factor of safety and allowable stress/strain for the buried lifeline structures.(AU)