Study On The Dynamics Of Ship-Bridge Collision And Anti-Collision Device Of Pier

With the increasing number of bridges crossing rivers and the rapid development of vessel transportation in our country, ship collision accident occurs more frequently than before. Reports indicate that ship collision is the third most common reason of large scale bridge collapse and also imply that bridges are still threatened by ship collision even though current bridge design meet navigation clearance requirements. Therefore, it is necessary to conduct research for bridge anti-collision design with the design of bridge.Firstly, formulas frequently introduced to calculate collision force between ship and bridge were summed up in this thesis. Parameters of those formulas were studied and discussed in this thesis. Secondly, the study adopted finite element software ANSYS to build piers and ship models, validities of different material models, boundary conditions and simplified mechanical models were studied and discussed. The LS-DYNA Solver was used in the collision analysis between ship and bridge, relation among impact force, ship mass and ship velocities were explored and discussed. Finally, protective effect of the device equipped on piers was verified by analyzing energy absorbing effect of FRP anti-collision device when ship collides piers under different velocities.The main conclusions are as follows:(1) For ship bridge collision analysis, the effect of water on ships, the effect of soil on the pier should not be ignored,in this thesis,4 percent of the ship quality was considered as water effect added to ship mass, which can achieve good results verified by a lot of scholars. To consider effect caused by soil, models focus on soil-pile contact and pile foundation model were separately deployed and analyzed based on finite element stimulation. Results indicate that calculation is more reliable when taking pile and soil effect into account. (2)Different cases were considered since different impact velocities or ship mass may lead to apparently different results. Analysis results imply that the relationship between impact force and ship speed is approximately linear. So does the relationship between impact force and square root of ship mass. Also the results prove that the theoretical formula is valid. (3)Mechanical model of FRP anti-collision device was established and four different load cases were taken into account. Numerical stimulation analysis indicates that energy absorbing effect of FRP anti-collision device is good since the following phenomenon were observed:impact force reduced by more than 75% of its initial value and displacement of pier also decreased a lot.