Reseach On Ship Collision And Auticollision Device For The Vertical Curved Pier Of Long Span Cable-stayed Bridge

The inland navigation in China is prosperous,and there are many kinds of navigable ships and large traffic flow,and the ship collision accident is often seen,which caused serious economic losses and casualties.So the shortcomings of bridge anti-collision design and anti-collision measures in China are described.Nowadays,the cable-stayed bridge structure is more versatile and aesthetical,and new structural forms increase the difficulty of collision avoidance design.However,there are still few studies on bridge anticollision in large size special-shaped pylon piers at present,and there is not enough attention to the design of energy absorbing materials in bridge anti-collision design.So this paper carries out research on anticollision of cable-stayed bridge vertical curve pylon based on numerical simulation according to a large span public and iron dual purpose Yangtze River bridge project.First of all,the domestic and international norms and empirical formulas about collision loads were introduced and summarized,the differences and reasons of each calculation method were compared and discussed.According to the navigation standards and fortification requirements of the Yangtze River Bridge,the process of impact between representative ship and water droplet bridge tower and vase type auxiliary pier of cable-stayed bridge were simulated by explicit dynamic analysis software LS-DYNA.The change rules of energy,ship damage and pier displacement during the collision under different water level and different impact angle were obtained.The distribution characteristics of ship impact load time history at different water levels were summarized,and the standard values of the collision force of piers were determined combined with the simplified calculation methods.Secondly,based on the unique structural form of the tower pier and anticollision requirement of the cable-stayed bridge,combined with the excellent energy absorption performance of closed cell aluminum foam,a steel-aluminum foam filled structural self-floating anticollision steel box device was put forward.On this basis,the collision process of 5000 t class ship and vertical curvilinear main tower of cable-stayed bridge at high water level was selected as the research object,and the stress characteristics of anticollision steel box and the filled aluminum foam material were studied by simulation.Compared with the impact of ship and bare pier,the anticollision effect of the collision avoidance device in reducing the impact force and the ship's collision depth,energy absorption and reducing the pier displacement was obtained.By comparing with other types of anticollision facilities,it is known that this anticollision device has outstanding energy absorption performance and the ability to protect the ship on the premise of greatly reducing the impact force of the ship.Finally,the impact parameters analyses of the crashworthiness of steel-aluminum foam filled structural anticollision device were carried out by the control variable method.The effects of aluminum density,structural stiffness,collision speed and angle on structural crashworthiness were discussed from aspects of impact force,energy absorption of anticollision device,damage of ship and anticollision device respectively.The change laws of the indexes such as impact force peak,specific energy absorption and structural collision depth were obtained.In order to improve the crashworthiness of anticollision device,the relevant technical methods were put forward,which can provide reference and guidance for this kind of anticollision research.