Tension Force Measurement of Sagged Cable with an Intermediate Support

The vibration method based on the string vibration theory is often used to estimate cable forces from measured natural frequency, and it is widely applicable to the construction control, performance evaluation and long-term health monitoring of cable-stayed bridge and tied arch bridge as well. However, the string vibration theory ignores the effects of flexural rigidity, sag of inclined cable and the intermediate support such as anchor tube or attached damper, which will cause unacceptable errors in practical applications. This paper proposed a practical explicit expression for vibration-based cable-force measurement by using energy principle. The capabilities of the method are verified by a numerical simulation on three cables with intermediate supports.