Ship-bridge Collision Analysis Based On The Ship Equivalent Model

Ship-bridge collision problems have been paid lots of attention. Further analysisof ship-bridge collision are complex and nonlinear. During the research about thesafety of bridge and dynamic response, simplifying the model ship appropriately wouldincrease the efficiency of the analysis of ship-bridge collision. Therefore, This thesiswill focus on the equivalent mass-spring of model ship during its collision. It willprovide supports for dynamic response of the whole bridge in the case of ship-bridgecollision. The main contents includes:①Based on the impact force curves from fine analysis of ship-bridge collision,we could see the impact force curves are made up of a smooth curve and jaggedfluctuation. The smooth curve is decided by the mass, stiffness, damping and velocityof the ship. It’s the main factor which will influence the result of the analysis ofship-bridge collision. And the jagged fluctuation is caused by the local failure of theship bow when it is being destroyed. Depending the structure of the ship bow, the localfailuere will differ. Therefore, the mass-spring equivalent ship model is proposed to beused in the analysis of ship-bridge collision. Cosequently, those general data of themass, stiffness, damping and the impact velocity of the ship could be reflected in themodel. This method will effectively simplify the analysis of ship bridge conflict.②By using the mass-spring equivalent ship model, we come up with theanalysis of Ship striking the rigid-body. stiffness coefficient and damping coefficient ofthe equivalent model influence the impact force and the energy conversion. Theanalysis showes that the impact force time-history curve includes the linear growth ininitial period and the smooth nonlinear growth curve in late period; The maximumimpact force and contact time are affected by the Stiffness coefficient. If the stiffnessgets higher, the maximum impact force will get stronger while the contact time will beshorter. However, the stiddness has little affect on collision energy conversion; As forthe damping coefficient, if it grows bigger, it will lead to following results:1.Theincrease of the linear growth of impact force time-history curve in initial periodbecomes bigger;2.The strongest impact force decreases.3.The strongest impact forceappears ahead of time. Besides, the more energy the ship absorbs in the collision, theless the residual kinetic energy there will be after the collision.③After setting up the ship-bridge collision analysis model, which is based on the mass-spring equivalent model, we can see from the report that due to the dynamicresponse of the piers during the collision, clearly there is a slight fluctuation near thetime-history curve of the impact force; There should be some deterministic nonlinearfunctional relationships existing respective between the spring stiffness coefficient,damping coefficient and impact force of the equivalent model ship. Through therelationships, we would know the spring stiffness coefficient of the equivalent modelship.④This method is about the inversion of the spring stiffness coefficient anddamping coefficient of the equivalent model ship by studing the maximum impactforce. Taking a5000DWT ship collision for example, if we use this methiod, the resultdemonstrates that it is feasible.