Intelligent Skyscraper Monitoring System Based on GPS and Optical Fibre Sensors

The collapse of the World Trade Center (WTC) has reminded us of the importance of structural integrity monitoring for improving disaster preparedness and response. A real-time system based on GPS and optical fibre sensors for monitoring structural integrity of the skyscraper has been proposed. In the designed system, there are 4 RTK GPS receivers atop the skyscraper on the vertices and 4 groups of several strings of optical fiber Bragg grating (FBG) sensors deployed along the 4 edges of the perimeters. The GPS sensors are used to measure the 3D positions of the vertices so that strain, tilt and rotation of the skyscraper can be determined. The vibrations of the skyscraper can be measured directly if an external reference GPS receiver is used together with the rover receivers atop the skyscraper at high sampling rate. The optical fiber Bragg grating (FBG) sensors are used to measure both strain and temperature. The conceptual design of the combined system of GPS and optical fiber sensors was based on the dimensions of the WTC. Then the first experiment involving Trimble MS750 GPS receivers, velocimeters and accelerometers indicates that the GPS RTK results are in good agreement with the results of velocimeters and accelerometers integrated once and twice respectively. The GPS resolutions for strain, tilt and rotation of the skyscraper are 50 micro-strain, 5”, and 45” respectively. In the second experiment involving the optical fiber Bragg grating (FBG) sensors, resolutions of one micro-strain change and 0.1 degree temperature change have been demonstrated. The system proposed here may also prove to be useful for the monitoring of other structures.