Intrinsic Damping of Cable Stay bridge – full scale field testing and a regression model for prediction

Stay cable vibration excitation such as wind induced, vortex, wake galloping or rain-wind combination may conduit to the risk of fatigue of the bridges structure components and then reducing the service life of the bridge. Most of the design criterions proposed by International Standards on stay cable bridges are based on the Scruton number (Sc), the important parameter directly related to the stay cables Intrinsic damping. Furthermore, the cable inherence damping depends on parameters of system and environment and the prediction of accurate value is difficult. Field testing is generally considered as the most effective solution to evaluate and/or verifying the damping characteristics. In this paper, we present the in-situ damping tests campaign performed on a new built stay cable bridge in Vietnam with large diversity of stay cable characteristics. Based on the measurement data, a regression mathematical model is proposed for damping prediction as the function of frequencies, cable lengths, unit weigh and cable inclination. The coverage verification shows that the proposed model can representing well the damping characteristic of the stay cables on the bridge.