Abstract and Contents

A database has been developed that documents performance of substation equipment in twelve California earthquakes. Equipment in the database is owned by Pacific Gas & Electric, Los Angeles Department of Water and Power, Southern California Edison and the California Department of Water Resources. The majority of data relates to equipment operating at 220/230 kV and 500 kV. The database is organized into an EXCEL 5.0 spreadsheet with 68 data fields describing earthquake location, ground motion, site location and conditions, equipment characteristics, performance of equipment, failure mode, and restoration time. Each record represents a single piece of damaged equipment or several pieces of similar undamaged equipment.

Ground motions in the database are based on recordings if the site was instrumented. In other cases, ground motions are based on event specific attenuation relationships developed by Somerville and Smith (1999).

The purpose of the database is to provide a basis for developing or improving equipment vulnerability functions. Data have been summarized by earthquake, site, and equipment type. Probabilities of failure are calculated by dividing number of damaged items by the total number of items of that type at the site. Using peak ground acceleration as the ground motion parameter, failure probabilities are compared with opinion-based fragility curves for a few selected equipment classes. Comparisons are somewhat crude in that the calculated failure probabilities do not include information about the mode of failure. The comparisons indicate that some of the existing fragility curves provide reasonable matches to the data and others should be modified to better reflect the data.

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Report Table of Contents

List of Figures
List of Tables


1. Introduction


2. Summary of Database Contents

2.1 Format of Substation Equipment Database
2.2 Sources of Substation Equipment Damage Data
2.3 Summary of Data
2.4 Limitations of Damage Data 


3. Essential Parameters for Defining Equipment Fragilities


4. Utilities Working Group Equipment Classes


5. Comparison of Database Statistics with Utilities Working Group Fragilities

5.1 Failure Modes
5.2 Data Comparisons


6. Future Database Development


7. References


Appendix A -- Description of Substation Damage Database Structure

A.1 General Description of Database
A.2 Format of Database
A.3 Earthquake Data Fields (columns A through 0)
A.4 Substation Data Fields (columns P through AJ) 
A.5 Equipment Data Fields (columns AK through BN)
A.5.1 Notes


Appendix B -- Ground Motion Spectra for Selected Substations and Earthquakes

B.1 Development of Ground Motion Spectra
B.2 Plots of Ground Motion Spectra


Appendix C -- Fragility Curves Developed by Utilities Working Group

C.1 General Description of Fragility Curves
C.2 Parameters and Plots of Fragility Curves