LabVIEW and CompactRIO monitor for earthquakes

National Instruments has announced that the China Earthquake Administration (CEA), the leading government body managing the country's earthquake preparedness and disaster mitigation, has selected a structural health monitoring (SHM) system developed by National Instruments Alliance Partner CGM Engineering, Inc, based on the NI LabVIEW graphical system design platform and NI CompactRIO programmable automation controllers. The systems are designed to aid engineers in conducting structural health research on seven recently constructed megastructures in China including both of the main venues for the 2008 Summer Olympics - the Beijing National Stadium (see photo) and the National Aquatics Centre.

Chris McDonald, Vice President of CGM Engineering, explains: "The main objective of this civil engineering project is to develop a state-of-the-art solution to monitor structural health characteristics including stability, reliability and livability in real time by using contemporary computing, sensor and communication technology. Our systems are designed to capture the vibrational signatures of structures and detect any sudden shifts of structural characteristics to improve structures and help reduce the loss of life and property when catastrophic events such as earthquakes, hurricanes or fires occur."

System configuration

The nine 64-channel and two 36-channel SHM systems each contain multiple CompactRIO controllers that directly connect to accelerometers for vibration measurements and an external GPS receiver for inter-chassis synchronisation. Within each chassis, the LabVIEW FPGA Module is used to synchronise each measurement channel to within +/-10 microseconds of the GPS-disciplined clock. The LabVIEW Real-Time Module is also used to program 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 to +70degC.

Each SHM system performs continuous, real-time monitoring at its 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 CEA selected this system because it offers continuous, real-time monitoring, time-based GPS synchronisation and the highest channel count for the lowest cost. The technology also provides a simple, out-of-the-box setup and a variety of I/O options that can be quickly and easily reconfigured to meet changing system requirements.

In addition to the Olympic venues, the SHM systems are deployed in the 104-story World Trade Centre in Shanghai, the 66-story Park Hyatt Hotel complex in Beijing, a 240m concrete arch dam in Ertan, an 8266m cable-stayed bridge in Shan-Tou, and a base-isolated CEA data centre 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.

To learn more about structural health monitoring using NI products, visit www.ni.com/data_logger/structural_data_logger.htm. Alternatively, use the form on this page to request a callback or more information.