Olympic structures being monitored

The China Earthquake Administration, the government body managing the country’s earthquake preparedness and disaster mitigation, has selected a structural health monitoring system developed by National Instruments Alliance Partner CGM Engineering.

It is based on the LabVIEW graphical system design platform and 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 the main venues of the Olympics — the Beijing National Stadium and the National Aquatics Centre.

“The main aim 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,” said Chris McDonald, vice-president of CGM Engineering.

“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.”

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 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 NEMA enclosure, which permits the unit to operate in high humidity and temperatures ranging from -40°C to 70°C.

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 email notifications when events occur.

In addition to the Olympic venues, the SHM systems are installed in the 104-storey World Trade Centre in Shanghai, 66-storey 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 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.