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With the continuous development of prestressing technology, cables have been widely used in structural engineering. A special concern in practical engineering is selecting the appropriate cable force measurement technology. This paper analyzes and introduces the principle of cable force measurement technology commonly used in current engineering from three aspects, namely, strain, vibration and wave fluctuation, and force balance. Combined with an actual project, the selection and arrangement of measuring points in the cable pre-tension measurement and other issues are discussed. The engineering example shows that the cable force measurement method based on FBG sensor presented in this paper can capture the action of each construction tensioning operations in real time and accurately. Monitoring the tension of the structure in real time is convenient for engineers and technician. The process is suitable for cable force monitoring during the construction tensioning stage. Furthermore, the EM sensor has good stability and durability and is suitable for long-term cable force monitoring.

A novel structural damage localization method based on modal strain energy changes is proposed. The proposed method does not utilize the first several modes together as usual but selectively makes use of some sensitive modes for each element. Both the magnitude of normalized elemental modal strain energy and the capability of each element to resist identification uncertainties are considered to determine the sensitive modes. Elements’ capability to resist identification uncertainties is calculated by using the Monte Carlo method. Based on determined sensitive modes, an in-turn damage-checking process is employed to judge the damage state of each element. A typical planar truss is numerically analyzed. The results show that the proposed method is more effective than that based on modal strain energy change ratio even when using the first several modes together as usual. Furthermore, by utilizing some sensitive modes only, the proposed method becomes much more robust, making damage localization more easy and reliable.