The three main objectives are:
- Perform quasi-static testing of rigid buses of different shapes, including offsets and bends.
- Coordinate with on-going projects 403, 404 and 408 to refine properties and representation of generic equipment, and modification of input motions of equipment appendages
- Perform shake table tests of several pairs of refined generic equipment interconnected by rigid bus of different shapes, including improved connectors.
This project is a continuation of a PEER Phase II Lifelines Program project in which several different types of rigid bus connectors were tested statically (cyclically loaded) and dynamically. Rigid buses with actual hardware were erected between supports with varying dynamic characteristics (natural frequency and mass), and were subjected to earthquake ground motions. These test results were used to validate analytical methods that were developed to consider the interaction of connected equipment during seismic loading.
This project will builds upon the results gained from the Phase II study, and investigate other factor and considerations that may be significant, but were not included in the previous phase of work. Also, improved connectors that were re-designed as a result of the Phase II study are being investigated in this project.
This research project consists of the following three main phases:
Phase 1: Quasi-Static Tests of Rigid Bus
In this phase of the study, quasi-static cyclic tests were performed on various types of rigid bus-connector assemblies. These tests were performed in the longitudinal directions of the bus assemblies under a prescribed displacement history. Two types of rigid bus-connector assemblies were tested: the S-shaped spring connector proposed recently by researchers at the University of California, Berkeley and the improved slider connector, re-designed recently by PG&E engineers.
Phase 2: Shake Table Tests of Pairs of Generic Equipment Interconnected by Rigid Bus
In this phase of the study, shake table tests are currently being performed on pairs of generic substation equipment connected by various rigid bus assemblies. Simulated horizontal ground motions are being applied separately in the longitudinal and transverse directions of the bus assemblies by the uniaxial earthquake simulation facility at UC-San Diego. Figure 1 shows a photograph of a pair of generic equipment connected by the S-shaped spring connector ready for testing on the shake table.
Phase 3: Validation of Numerical Results and Design Recommendations
In the last phase of the study, the experimental results obtained in this project will be compared against the numerical simulations conducted in a parallel project at the University of California, Berkeley. This comparison will include an examination of the discrepancies between the experimental and analytical results, and a resolution or discussion of the reasons for the differences. Also, recommendations will be made on the types of rigid connectors to be used in practice based upon their performance in the shake table interaction experiments conducted in this project.
The first phase of the project has been completed in Year 5. The second phase is currently underway and will be completed shortly. The third phase of the project will be completed by the end of Year 6.
Similar work on substation equipment interaction is being conducted by other electrical utilities including BC-Hydro and Hydro-Quebec.
The project should be completed in year 6.
By its nature, the results of the PEER Lifelines Program are being used rapidly by utilities. The rigid bus sliders considered in this project are new design by industry based on previous results of Phase II.
The project is on schedules and the principal milestones are shown in the table at right.
The main deliverables of the project are design recommendations for the interconnection of substation equipment with rigid bus.