Seismic Isolation of an Internet Service Exchange Facility: AboveNet ISX ― SF1

摘要

This paper describes the design and construction of the AboveNet ISX - SF1 project in San Francisco, California, which consists of a seismic isolation upgrade of a 1940's non-ductile reinforced concrete warehouse and its conversion into a state-of-the-art Internet "co-location" facility. The completed Internet Service Exchange (ISX) facility nouses client computers for major companies with their Internet servers tied into AboveNet Communications, Inc. global optical fiber network. Customer equipment is protected by redundant MEP support systems in an essential facility designed to achieve the performance goal of continued operation following minor and major earthquake ground shaking. This paper also addresses the fast-track delivery challenges including existing building unknowns, schedule, early procurement of seismic isolators, complex mechanical and electrical system requirements, expedited building permit process, design and construction peer review, and an accelerated construction schedule. The summary includes an overview of structural design criteria including seismic hazard evaluation, seismic performance goal and 1998 California Building Code (CBC) earthquake regulations for seismic-isolated structures. Analysis and design of the isolation system, as well as, substructure and superstructure strengthening will be summarized based on dynamic non-linear response history, a "modified" CBC static analysis procedure, and additional analyses to account for effects of overturning "uplift" and vertical acceleration on the isolation system. The seismic isolation system design section includes a description of the Friction Pendulum System (FPS) bearing and its implementation on this project. Discussion includes prototype and production bearing testing and quality control requirements. The project was completed and received tenant occupancy permits in March 2001 - approximately one year after commencing the preliminary design for the project. The anticipated superior seismic performance of the facility is further illustrated through a conventional "Probable Maximum Loss" (PML) analysis applied to the completed isolated structural retrofit. Results of this analysis are briefly summarized.