The Optimization Design Research Of Bridge Anti-collision Facilities Made By Composite Material

With the rapid development of transportation industry in our country,China has total more than 800 thousand highway bridges and more than 200 thousand railway bridges by the end of 2016,and has become the largest country of bridges in the world.The increasing number of bridges,especially bridges over rivers and seas,caused increasing risk of ship collision with bridges.In order to prevent the ship-bridge collision accident,bridge designers have adopted many corresponding preventive measures,which include installation of passive anti-collision devices for existing bridges or under-construction bridges.The function of the collision preventative device is to reduce the damage to the bridge by changing impact direction of the ship or reducing impact force of the ship,at the same time to decrease the damage to the ship and collision-preventative devices as much as possible.In our country's many bridges,pier protection device for bridge-ship collision has been widely used.However,there are some problems for large steel structure anti-collision device.Examples are,either the designed impact bearing capacity has greatly exceeded the true value of usual ship-bridge collision,or optimization according to the ship-bridge collision mechanism is not performed which caused huge waste of manpower,material and money.The reasons are mainly caused by two aspects.The first reason is that,due to contemporaneous factors,estimation of ship collision mechanism and the collision force is not accurate enough,thus the impact bearing capacity needed by the protective devices are calculated wrong.This second reason is that the structure form can be further optimized,to reduce structure weight and decrease construction and maintenance cost.Based on the research of composite anti-collision box,this paper used numerical simulation method,and studied the optimization design of several types of collision-preventative box.This paper conducted simulation analysis of ship-bridge collision by nonlinear finite element software LS-DYNA,and performed optimization design of composite box set using software MATLAB.The main research of this paper is as follows:?We adopted finite element analysis method,established the ship impact model of composite box.Through the simulation analysis of different composite anti-collision levels box with three different buffer tube arrangements,we obtained the dynamic time history curves of the ship collision force and box collision depth.?We conducted pseudo static finite element method simulation and calculation for the three types of arrangement of the different collision resistant categories,and obtained the compression stiffness for each box by analysis.?We analyzed synthetically the dynamic response and compression stiffness of the composite box,and summarized the reasonable stiffness arrangement of box.At the same time,we found the most reasonable arrangement form of the buffer cylinder in each collision category.? We considered two parameters of set box shell thickness and buffer tube wall thickness as the optimization design variables,randomly selected sample points to perform numerical simulation calculation,and obtained the corresponding total impact force of ship collision,box total mass and total internal energy box absorbed.Then,the three types of composite box with the collision grade were selected,and the value of the sample was obtained by simulation optimization study.? Through the concrete engineering project,the paper introduced the general process of ship-collision-prevention design of pier,and the simulation results verified the rationality of the range of reasonable rigidity of composite box's stiffness range.Finally,the anti-collision box is optimized and analyzed.At the end,this paper discussed the future of the research on the optimization design of the composite box,and made conclusions from this paper's results.