Study On The Calculation For The Ship Impact Force Under Ship-Bridge Impact Scenarios

As the development of waterborne trade and the rapid increase of the number of bridge across the river and sea,ship-bridge impact accidents are becoming more and more frequent.Not only will ship-bridge impact accident do great harm to the ship and human beings,but also can destroy the bridge.In order to decrease the damage of the bridge after ship impact,it is very necessary to do some estimations of the ship impact force during ship-bridge impact at the preliminary stage of bridge design.Thus,combining analytical method,experiment method,empirical formula method and finite element simulation method,the thesis will discuss the calculation of ship impact force during ship-bridge impact.Firstly,the crushing force of a bulbous bow in a 5000 DWT bulk carrier is calculated by intersection unit method,which is then compared with the crushing force calculated by quasi-static dented finite element simulation,and a modification specific to large-angle inclined element of the simplified method is proposed.Secondly,according to the bow structure of a 5000 DWT bulk carrier,2 simplified reduced scale bulb models and 1 simplified reduced scale upper structure are designed,and then,for validating the effectiveness of the modified simplified method and finite element simulation,quasi-static dented experiments are conducted.Thirdly,the modified simplified method and external dynamics are combined with each other,where an analytical method for calculating ship displacement-force curves during ship-bridge impact is obtained.Meanwhile,this analytical method is verified by finite element simulation,and an equivalent ship impact force fitting formula is put forward,which can give a good estimation to ship impact force under ship-bridge impact scenario.Fourthly,finite element models of 3000 DWT,5000 DWT,10000 DWT bulk carriers and the 1^st bridge of Wuhan Baishazhou Yangtze River Bridge are established,with which 13 ship-bridge impact simulations are carried out,and the ship displacement-impact force curve of each working condition is obtained.Finally,5 commonly used empirical formulae for ship impact force calculation during ship-bridge impact are introduced,and together with the fitting formula,the impact force of 13 working conditions mentioned above are calculated,which are then compared with simulation results.After that,according to the ship type and some reduction of the initial kinetic energy,the fitting formula proposed in this thesis is modified,and some adjustment suggestions for 2 empirical formulae are present.In this thesis,some formulae which can rapidly and accurately estimate the impact force during ship-bridge impact are acquired,which may be meaningful at the preliminary stage of bridge design.