Dynamic Deformation Monitoring of Tall Structure Using GPS Technology

Abstract

Dynamic deformation monitoring of structures such as long bridges, towers, and tall buildings, for the purpose of determining structural vibrations, is now possible using global-positioning-system (GPS) technology. Current non–GPS techniques for measuring structural vibrations (these include vibration measurement with accelerometers, vibration measurement with a laser interferometer, and vibration measurement with an electronic distance measurement instrument) are first briefly outlined, with advantages and disadvantages noted. The specific application, measurement of structural vibrations in the Calgary Tower, Calgary, Alberta, Canada, using GPS receivers in differential mode, is then described. The results show that the Calgary Tower, under wind loading, vibrates with a frequency of about 0.3 Hz in both north-south and east-west directions. The 0.3 Hz vibration frequency measured on the Calgary Tower is within the range of 0.1 Hz to 10 Hz expected for structures of this type. When the capability of GPS to monitor structural vibrations is verified by further tests, it could be adopted as a standard technique.