Study On Crashworthness Of FRP Combined Anti-Collision Box

Ship-bridge collision accidents usually lead to catastrophic consequences.In recent years,the traffic construction in China has been developing rapidly;the number of bridges across the channel has increased year by year,and the accident rate of ship-bridge collisions has been increasing.Therefore,in order to reduce the loss in ship-bridge collision accidents,it is of great significance to carry out research on bridge anti-ship collision.Based on the theory of structural vibration,the ship-bridge collision model is simplified,and the impact response of pier is calculated by the mode superposition method;for the bare pier and FRP combined anti-collision box cases,the finite element numerical simulation is performed to verify the correctness of theoretical calculations;Compared with the cases of bare pier and steel anti-collision box,the crashworthiness of the combined anti-collision box is studied.According to the combined anti-collision box structure,the section stiffness and crashworthiness of the composite steel-symmetric laminates structure are studied.Research on the“mi”shape substructure of laminates:Firstly,the crashworthiness of laminates with different number of substructures is studied.Then the genetic algorithm is applied to the stacking sequence optimization of the symmetrical laminates with two“mi”shapes by LS-OPT software.The crashworthiness of the FRP-steel pipe composite structure is studied to improve the combined anti-collision box's performance as well as providing relevant suggestions for it's structural design.The main results of the above research are as follows:1.The results of pier impact response calculated by FEM agree well with that by the mode superposition method.This theoretical calculation method has certain reference significance for the theoretical analysis of ship-bridge collision.2.The FRP combined anti-collision box performs well.It can not only greatly reduce the pier impact response,but also can effectively reduce the impact force of the ship.It protects the bridge as well as the ship;the combined anti-collision box is better than traditional steel box in corrosion resistance and crashworthiness,more economical than pure FRP anti-collision box.Considering the economy,durability and crashworthiness,FRP combined anti-collision box is worthy of recommendation.3.Under the same conditions,the steel-symmetric laminates composite structure which composed of symmetrical laminates containing“mi”shape substructure has the minimum stiffness.4.Laminates containing different numbers of"mi"shaped substructures perform differently.The symmetric laminates composite structure with two“mi”shape substructures has the best comprehensive performance.The crashworthiness of this composite structure is most sensitive to the orientation of the outermost two unidirectional laminates,and the most insensitive to that of the middle layer.5.For the stacking design,in order to reduce the impact force of the laminates,it is recommended to reduce the angle difference between the adjacent layers.Besides,the 0~°unidirectional laminate which stiffness is great,should be set in the middle of laminates where the impact force is the less influenced by the stacking orientation6.As for the combined anti-collision box structural design,the flexible member should be installed on the collision side of the box,and the structural stiffness of the box should be appropriately increased on the protective side.The combined anti-collison with steel pipe performs better.