Effect of baseline calibration on assessment of long-term performance of cable-stayed bridges

To enable the long-term health monitoring and condition assessment of a long-span cable-stayed bridge, a reasonable baseline finite element model to reflect the current structural behaviour is indispensable. With proper calibration, the model provides realistic predictions of the static and dynamic behaviour. This paper describes the development of baseline model of Ting Kau Bridge in Hong Kong using the cable forces as the basic parameters, with the measured frequencies and the initial equilibrium configuration of the bridge as the reference. Methods to estimate the fatigue lives of structural components are reviewed with special attention paid to the mean stress effect. The short-term performance and long-term performance of Ting Kau Bridge are studied based on both the initial model without baseline calibration and the baseline model. While the stress amplitudes due to moving loads do not change much, the mean stresses do change at many critical locations. As the mean stress effect is significant in the estimation of fatigue lives, baseline calibration of cable-stayed bridges is considered essential.