Study On Dynamic Response Of Ship Bridge Collision Based On Contact And Coupling Nonlinear

With the rapid development of road and rail transport network, the number of bridges crossing the busy shipping lanes grows quickly, ship bridge collision problem is paid more and more attention. Ship bridge collision belongs to the typical problems of impact dynamics and the dynamic response analysis of ship-bridge system is of great significance. For the ship-bridge flexible multi-body system, previous study is confined to the scope of elasticity, and fails to consider contact nonlinear, damping and pile-water coupling nonlinear. Therefore, it is of great significance to improve the bridge of flexible multi-body system model and analyze dynamic response.The ship-bridge flexible multi-body model is improved by considering contact nonlinear at the impact position, bridge structure damping and pile-water coupling nonlinear--hydrodynamic pressure effect. Then the nonlinear Lagrange differential equations can be established and an adaptive Runge-Kutta method is adopted for numerical solution, which can get the dynamic response of time domain rapidly. The results of considering and not considering contact nonlinear, structure damping and hydrodynamic pressure effect are analyzed. The main research contents are as follows.At first,the ship-bridge multi-body system becomes non conservative system after considering contact nonlinear, structure damping and hydrodynamic pressure effect. Then the ship-bridge Lagrange equation considering non conservative force is derived. After that, the nonlinear Lagrange differential equations can be established and an adaptive Runge-Kutta method is adopted for numerical solution.Then bow deformation model proposed by Zhang and Pedersen is introduced in the research of ship-bridge contact nonlinear and expression of nonlinear impact force can be obtained. Then the expression is substituted into the nonlinear Lagrange differential equations for numerical solution. The results of considering and not considering contact nonlinear are analyzed. It shows that the displacement of pier top is significantly less than the linear solution after considering contact nonlinear. Then the peak impact force calculated is compared with main design codes, it shows that nonlinear solution is more accurate than the linear solution, which verifies the necessity of introducing contact nonlinear.Once again the Rayleigh damping model is introduced in the research of bridge structure damping and expression of nonlinear impact force can be obtained. Then the expression is substituted into the nonlinear Lagrange differential equations for numerical solution. Then the results of considering and not considering bridge structure damping are analyzed, it shows that damping has a great effect on the displacement of pier top, but not much on impact force. In addition, relationship between dynamic response and different parameters is studied, it shows that dynamic response increases with the increasing of the impact velocity and ship quality..Finally Morison equation is adopted for calculation of hydrodynamic pressure effect. The results of considering and not considering hydrodynamic pressure effect are analyzed. It shows that dynamic characteristics of bridge is changed after considering hydrodynamic pressure effect and dynamic response increases obviously, which verifies the necessity of introducing hydrodynamic pressure effect. In addition, the results of considering and not considering the hydrodynamic damping are analyzed. It shows that the contribution of the hydrodynamic damping to ship-bridge calculation is small and can be neglected in simplified calculation.In this paper, we can draw a conclusion that contact nonlinear, structure damping and hydrodynamic pressure has great effect on dynamic response and should be considered in the related research.