1 Copyright © 2018 by ASME Proceedings of the 37 th International Conference on Ocean, Offshore and Arctic Engineering OMAE2018 June 17-22, 2018, Madrid, Spain OMAE2018-78728 NUMERICAL INVESTIGATION OF THE COLLISION DAMAGE AND RESIDUAL STRENGTH OF A FLOATING BRIDGE GIRDER Yanyan Sha Center for Autonomous Marine Operations and Systems (AMOS) Department of Marine Technology Norwegian University of Science and Technology Trondheim, Norway Email: Yanyan.sha@ntnu.no Cato Dørum Norwegian Public Roads Administration, Hamar, Norway Jørgen Amdahl Center for Autonomous Marine Operations and Systems (AMOS) Department of Marine Technology Norwegian University of Science and Technology Trondheim, Norway Zhaolong Yu Center for Autonomous Marine Operations and Systems (AMOS) Department of Marine Technology Norwegian University of Science and Technology Trondheim, Norway ABSTRACT For bridges across wide and deep waterways, fixed foundation structures are not possible to be built due to technical restrictions. Alternatively, pontoon supported floating bridges which do not require fixed foundations can be installed. As the girders of floating bridges may have a low clearance from the sea level, a critical design consideration is the capability of the girder to resist the collision of passing ships. It is hence important to investigate the collision response of the bridge girder and evaluate girder residual strength after the collision. In this paper, finite element (FE) models of a ship deckhouse and a floating bridge girder are established. The girder response to ship deckhouse collision is investigated through integrated numerical simulations. Parametric studies are conducted to compare the girder response for various girder designs and collision scenarios. The residual strength of the girder after in damaged condition is also investigated. Based on the numerical results, a residual strength index (RSI) is proposed for fast prediction of the girder damage level based on the absorbed energy. INTRODUCTION Bridge structures are under the threat of accidental ship collisions. Potentially, ship with large kinetic energy may cause serious damages to the bridge structures should a collision accident occur. Therefore, bridges should be designed with an adequate capacity to resist the collision loads without excessive structural damages. Ship-ship collisions were first studied by Minorsky [1], and Meir-Donberg [2] through collision experiments. Empirical force-deformation relationships and energy absorption curves were obtained. Later, the AASHTO [3] code suggested an equivalent static load for estimating the ship-bridge collision loads. However, Consolazio et al. [4] found the AASHTO- specified loads were substantially larger than those computed via experimentally-validated dynamic analysis for moderate to high energy impacts. More recently, finite element methods have been widely utilized in analyzing vessel-bridge collisions. Yuan and Harik [5] and Consolazio and Cowan [6] calculated the impact force of barge collision with rigid bridge piers. Sha and Hao [7, 8] further studied vessel-pier collisions with an emphasis on structural damages. Base on the numerical results, they proposed simplified equations for a fast estimation of the collision force [9]. Nevertheless, the vessel model in these analyses were typically barges, which have lower and shorter bows than seagoing ships. In addition, the displacement and travel speed of barges, and hence the kinetic energy, are much smaller than merchant ships. It is worth mentioning that all these works deal with the response of bridge substructures, i.e. piers, piles and pile caps. There has been little focus on the analysis of bridge superstructures against ship collisions [10]. Due to the