A Combined Method for Measuring Cable Forces: The Cable-Stayed Alamillo Bridge, Spain

The paper presents a combined method for measuring the forces in the cables of cable-stayed bridges based on measuring the natural frequencies of the cables in a free-damped vibration and subsequent calculation of the forces using simplified vibrating chord theory. The theoretical background and the practical and economic advantages of this method are discussed, as well as its most relevant limitations. The method is applied to an existing bridge in order to demonstrate that it can obtain reliable values for the forces in the cables.