Abstract Summary
Norway is a coastal country that relies heavily on ferry connections in order to provide efficient means of transportation for local communities and industries. Møre and Romsdal county, where the research was conducted has a population of 265.000, an area of 14.300 km2, and over 50 ferry docks in active use that needs to be regularly inspected and maintained. Some of them are part of the E39 coastal route – the main economical artery in Norway. Therefore a potential failure of an important ferry connection would lead to substantial economic losses and massive delays, as well as put a strain on smaller, surrounding road systems that were not designed to accommodate highway traffic. Although ferry docks can be considered to be relatively simple structures, they are often exposed to complex loading conditions caused by heavy traffic, docking operation, and a generally harsh environment. It should also be mentioned that the ferry dock works in two different modes: 1) as a separate structure, and 2) as a combined dock-ship structure when connected with a ferry, making their analysis more difficult. Moreover, there exists little knowledge about the dynamic behavior of those structures. Looking at the available literature it can be deducted that ferry docks, despite fulfilling the same role as bridges, did not receive even nearly a similar amount of attention among researchers in the past. This paper presents lessons learned from measurements on the Rykkjem ferry dock in the Møre and Romsdal county in Norway. Firstly, a description of a new instrumentation system will be given. The system was designed to be flexible and allow for fast deployment since the time spent on installing sensors and preparing for the data acquisition cannot disrupt the ferry schedule. Then, the challenges when creating a Finite Element (FE) model will be described. Here, there exist many parameters that are initially difficult to estimate such as the stiffness of large rubber support that allows absorbing horizontal forces caused by ferry docking, or the stiffness of the vertical supports provided by hydraulic towers. Results show that similarity between mode shapes obtained based on the FE model and measurements can be greatly improved with the use of the finite element model updating technique. Provided results indicate also that the finite element updating can be a useful tool for examining more closely the deterioration process taking place for different structural parts of the ferry bridge decks.
