Degenkolb and The Bowls Project
Mark Sinclair, Degenkolb’s New Technologies Group Principal, along with Gordy Wray, Degenkolb Project Engineer, have been volunteering their time to provide structural engineering support to The Bowls Project. The project was inspired by ancient Babylonian clay bowls and mixes music, history, architecture, and engineering together. It is the brainchild of local artist/musician Jewlia Eisenberg and Michael Ramage from the Department of Architecture at the University of Cambridge, England. When completed, the dome structure will house weekend performances by Jewlia’s band, Charming Hostess. The installation will be located at the Yerba Buena Center for the Arts during the summer. Currently, the crew is assembling the dome as the July 6th opening night approaches.
The team has been working hard to ensure that the unique dome adheres to the building code. Although the masonry of the structure will be reinforced with geotextile, San Francisco’s Department of Building Inspections considered the dome to be unreinforced masonry structure, which is not permitted. Mark and Gordy worked with Raymond Lui of the San Francisco Department of Building Inspection to reach agreement on an alternate means of compliance, which allowed the domes to be constructed on top of a base-isolated platform and tested at full scale. The conventional process for approving base-isolated systems involves prototype testing and peer review – testing alone would have exceeded the overall budget for the project. Using this alternate means of compliance, the isolation system has gone from conception to completion in less than 2 months. Upon completion of the domes, the platform will be pulled to the maximum displacement and released. Data will be collected to measure the acceleration of the platform, the damping ratio, fundamental period, and hysteretic behavior of the isolation system. The isolators use a ball and cone design licensed by Worksafe Technologies and were fabricated at American Steel in Oakland.
Seismic isolation is widely perceived as expensive and complex – and in the U.S. is usually considered much too expensive to use in small structures e.g. residential construction. Consequently, there are only a handful of residential applications in the U.S. However, there are over 3,500 residential seismic isolation applications in Japan! The Japanese more recent and more searing experience with the Kobe earthquake (over 6,000 lives lost) was the trigger that kick-started use of seismic isolation there. In the U.S. we have yet to have our Kobe, but this is merely a question of when, not if. By using a relatively low cost isolation system, such as the one provided by WorkSafe for this project, and the validation method adopted here, small building projects could become much more feasible.
Future applications of this seismic isolation technology can provide artists, architects, and engineers the ability to build innovative, efficient structures in high seismic areas with the assurance that the structure performs as intended.
You can check out the progress of the project at The Bowls Project blog thebowls.blogspot.com/
