The San Jose Center for Performing Arts was designed by architect Frank Lloyd Wright. Unfortunately Wright died prior to the completion of the project. Wright’s Grand Tier balcony design is unique and graceful, especially when viewed from the seating below, because it is only attached to the building structure at its ends and not along its back edge. Thus, the Grand Tier’s design is more like a bridge than like a conventional balcony. An unanticipated and undesired consequence of this bridge-like design is that it was sometimes excited to uncomfortable levels of vibration by audience-generated forces.
In the late 1980s Response Dynamics was hired to perform dynamic testing of the Grand Tier balcony structure (see photo). This testing revealed the presence of a low frequency resonance inherent in this design. The City of San Jose then had the Grand Tier's structural connections to the building strengthened to mitigate safety concerns. At the same time, San Jose specified that an innovative new digital computer-based vibration monitoring system be designed, developed and installed to continuously monitor the Grand Tier balcony vibration, and in the event of detecting vibration that exceeds an alarm level (specified by the project’s structural engineer) to automatically turn on the house lights and to play a message over the house sound system stating “For your comfort and safety please be seated in the balcony.”
Response Dynamics completed the design, programming and installation of the Grand Tier Balcony Vibration Monitoring System (GTVMS) in the spring of 1988 and for more than 25 years this GTVMS has been performing continuous simultaneous monitoring of the Grand Tier’s vibration from 8 accelerometers that are mounted to the steel framework supporting Frank Lloyd Wright’s Grand Tier balcony. Since 1988, Response Dynamics continues to maintain the GTVMS for San Jose. All eight of the PCB Piezotronics quartz accelerometers, and the associated PCB Piezotronics electronics, have been 100% dependable without a single failure in over 25 years of continuous operation. This corresponds to more than 200 accelerometer-years of continuous operation without a single failure!