The China Earthquake Administration has selected a structural health monitoring (SHM) system from CGM Engineering Inc. to help engineers conduct research on seven recently constructed megastructures. CGM, a National Instruments Alliance Partner, based the system on the NI LabVIEW graphical system design platform and NI CompactRIO programmable automation controllers.
The SHM system performs continuous, real-time monitoring at each location, and engineers can remotely access the locally stored data from anywhere in the world via secure Internet connections. Additionally, engineers can configure the systems using either a single or multivariate architecture to send e-mail notifications when events occur.
The SHM systems are deployed at two Olympic sites—the Beijing National Stadium and the National Aquatics Center—and the 104-story World Trade Center in Shanghai, 66-story Park Hyatt Hotel complex in Beijing, 240-m concrete arch dam in Ertan, 8266-m cable-stayed bridge in Shan-Tou, and base-isolated CEA data center in Beijing. Ultimately, the data collected from this research will be used to improve the structural integrity of future buildings and reduce the number of lives lost from catastrophic events.
The nine 64-channel and two 36-channel systems each contain multiple CompactRIO controllers that directly connect to accelerometers for vibration measurements and an external GPS receiver for inter-chassis synchronization. Within each chassis, the LabVIEW FPGA Module synchronizes each measurement channel to within ±10 microseconds of the GPS-disciplined clock. The LabVIEW Real-Time Module programs user-configurable filtering to prevent unwanted noise from interfering with the low-frequency measurements being acquired. Each system is encapsulated in a rugged NEMA enclosure, which permits the unit to operate in high humidity and temperatures ranging from –40°C to 70°C.