Measured dynamic response of submerged floating tunnels: A tool for further developments

A structural system identification methodology for large-scale measurements on dynamically sensitive structures is presented. The current implementation is primarily considering the identification of structural parameters without performing any load measurements. The method is however, capable of identifying parameters associated with both loading and structural characteristics. To provide a robust method, a two-step procedure is applied. Natural frequencies and corresponding modal damping ratios are identified with high accuracy in the first step, using Block Hankel matrices based on cross-covariance functions. The second step estimates physical structural property parameters by means of different estimators. The methodology has been used with great success on measurements obtained from several longspan bridges in Norway. Application of the methodology on a model of a submerged floating tunnel, which has been tested in an ocean basin, illustrates how this methodology may be utilised for calibration of a numerical model.