Abstract Summary
Ferry docks together with bridges are part of the critical infrastructure that makes it possible to establish connections between two destination points separated by a large body of water. For coastal nations with the majority of the population living by the sea, ferries and bridges are an indispensable part of almost any travel. One of such nations is Norway with its famous landscapes that often present a serious challenge when it comes to planning, building, and maintaining infrastructure. A potential failure or closure of one ferry dock can lead to substantial economic losses and massive delays, as one has to often drive far inland along the Norwegian fjords, or put a strain on smaller, surrounding road systems that were designed to accommodate traffic expected on the national highway. Therefore improved understanding of dynamic behavior of ferry docks and loads they are exposed can provide economical benefits in form of better fatigue design or more cost-effective maintenance. Norwegian standard N400 instructs that the following loads induced by the ferry should be consider in the design of the ferry dock bridges in Norway: • Impact load • Longitudinal pressure • Forced deformations The two latter ones should be considered to occur simultaneously with the traffic loads, while the impact load appears separately during berthing operation (vessel sway motion) according to N400. Longitudinal pressure is defined as the force along the bridge deck center line induced by the vessel pushing towards or away from the land (vessel sway and yaw motions), while forced deformations correspond to a rotation of the front of the ferry deck bridge that is in contact with a ferry. Those rotations arise from the fact that a ferry is not able to keep itself perfectly aligned with the horizontal plane as it is affected by wind and waves when attached to the ferry dock bridge, and it will transfer its own tilt to a ferry deck bridge (vessel roll motion). The ability to determine above mentioned loads under real-life conditions together with traffic loads is crucial for a proper estimation of fatigue service life, tracking deterioration process and finally, as a result of that, a cost-effective planning of inspections and maintenance schedule. If ferry-induced and traffic loads can be estimated accurately from measurements, then long-term monitoring will provide valuable data that can be used to validate the design approach and recommendations in N400. In this study we try to examine whether the impact load can be identified by means of kalman filter using measured acceleration time series and an updated finite element model.
