Real-Time Seismic Monitoring Of Veterans Affairs Hospital Buildings

This paper describes recent collaborative efforts made by the United States Geological Survey and Department of Veterans Affairs (VA) in real-time seismic monitoring of VA hospital buildings located in seismically active regions. The instrumentation in each building encompasses accelerometers deployed on all floors, a multi-channel recorder, and a server to analyze and archive the building's dynamic response in real-time. The server runs advanced structural health monitoring software, which consists of several data processing and analysis modules. Four different algorithms are implemented in four separate modules to compute shear-wave travel time, modal parameters, base shear force, and inter-story drift ratio from the measured vibration data from the instrumented building. The performance level and damage state of the building are estimated from the inter-story drift ratio and base-shear; the change in modal parameters and wave travel time is also used to detect and locate any possible damage zone(s) in the building. These algorithms are validated and verified using data from full-scale shake table tests. The information obtained from the real-time seismic monitoring system can be used to support timely decisions regarding the structural integrity of the VA hospital buildings immediately after an earthquake, and to help with inspections and necessary repairs and replacements.