Deformation monitoring of a super-tall structure using real-time strain data

Monitoring deformation of super-tall structures under different environmental conditions is an important and challenging issue in assessing the safety and serviceability of structures. This paper presents a new method for calculating structural deformation using real-time strain data, which can be easily measured at different sections. Assuming the structural deformation is of bending beam type, the deformation of the structure is associated with longitudinal strain. Virtual work theory is then used to calculate the horizontal displacement and tilt angle of the building on the basis of the strain data at different heights of the structure. The proposed method is applied to the 600 m tall Canton Tower (previously known as Guangzhou New TV Tower), on which a long-term structural health monitoring system including over 400 vibrating strain gauges has been installed at different heights. The displacements and tilts of the structure top under normal and typhoon conditions are calculated using real-time monitoring strain data. The calculated deformations show good agreement with the measurements by using global positioning system (GPS) and inclinometers. The temperature-induced maximum daily movement is similar to the value of typhoon-induced motion. Moreover, the displacement mode of the super-tall structure is also calculated and shows the bending type. Error analysis demonstrates that the calculated displacements have higher accuracy than the GPS-measured counterparts, and that the calculated tilts have similar accuracy as those measured by an inclinometer.