Investigation Of FRP Protective Device In Ship-Bridge Collision

With the vigorous development of transportation,the natural contradiction between the bridge across the navigable river and the ship has formed.The collision between the ship and the pier is inevitable due to the navigation environment,the condition of the ship,the management factors,the human factors and so on.The bridge pier is an important structure to ensure the integrity and safe operation of the bridge.In order to avoid the catastrophic consequences of the ship-bridge collision,it is of great practical significance to study the anti-collision of the bridge.In this paper,the combination of theoretical analysis and numerical simulation was used.Based on the principle of impact dynamics and the theory of stress wave,the internal mechanism of FRP protection device to reduce ship collision was proved.Then,the numerical simulation of ship-bridge collision was carried out.Evaluation of performance of FRP anti-collision device was investigated under three different cases,i.e.,without anti-collision device,with steel anti-collision device and with FRP anti-collision device.Then,the FRP-steel composite panel was optimized and two kinds of FRP-steel combined anti-collision device were put forward.The deformation and failure process of FRP-steel combined anti-collision device was simulated and it`s crashworthiness was evaluated.Finally,the influencing factors of ship-bridge collision were analyzed,including the impact velocity,mass,angle and the bow stiffness of the ship and so on,and the code formulas were analyzed and reviewed.The main achievements of this paper are as follows:(1)The Underlying causes of FRP anti-collision device reducing impact force is the Low-wave impedance characteristics of FRP materials.Compared with steel anti-collision device,the FRP anti-collision device can significantly increase collision duration,by exerting the flexible buffer effect,and thus can reduce the impact force imposed on bridge piers and ship with the magnitude of 36% and 30%,respectively,while protecting the pier and the ship.(2)Steel anti-collision device mainly dissipated energy by local deformation while FRP anti-collision device dissipated energy by global deformation and friction,which Energy dissipation patterns diverse.As for steel anti-collision device,It tend to form plastic deformation area in the partial area,resulting in a larger concentrated impact force,While FRP anti-collision device will convert the concentrated impactforce into weaker distributed loads,fully exerting the global crashworthiness.The global stiffness of FRP anti-collision device is relatively low,resulting in large deformations under impact loading of the ship.(3)The anti-impact and energy dissipation performance of the composite panel F5 is better than that of the composite panel G5.The position and distance of the steel tube in the composite panel affect the anti-impact performance of the composite panel greatly,With the increase of the thickness of the steel tube,the anti-impact of the composite panel increases,and the energy absorbed by the plastic deformation increased first,then decreased.(4)Peripheral FRP board of FRP-steel combined anti-collision device can play a flexible buffer effect,reduce the impact force,increase the anti-collision device corrosion resistance,and the steel tube in the middle of the structure can dissipate energy by deformation,reduce the cost of the anti-collision.The protection effect of the FRP-steel combined anti-collision device is obvious.(5)Under the same conditions,the impact force calculated by different National code formula is quite different.The AASHTO specification is suitable for the low velocity impact of the ship,and the empirical formula of the impact force of the Chinese Railway code is suitable for the large angle oblique impact condition.The impact velocity,mass,angle and the bow stiffness of the ship have comparatively large influences on the impact force,and the commonly used code formulas generally only consider the impact velocity and impact mass,and thus the empirical formula still needs to be further improved.