Anti-collision Analysis Of Solid Cylindrical Pier Of Bridge And Research On Optimization Of Protection Devices

Once the vehicle and Bridge collide,it will bring great loss to the national economy and people’s life and property.Therefore,domestic and foreign scholars have carried out a series of theoretical and Experimental Research on vehicle bridge collision and anti-collision devices,and put forward a variety of anti collision devices measures for some prone accident areas.There are many kinds of anti-collision devices.This paper mainly studies the anti-collision performance of the attachment anti-collision devices of different materials,which is of great significance to the theory and practical engineering application of the anti collision of piers.The main research work of this paper is divided into the following aspects:(1)The finite element model of vehicle impact on bridge pier is established by ANSYS/LS-DYNA software,and the important problems encountered in modeling are analyzed,such as the material constitutive relationship between vehicle and bridge pier,the contact selection between vehicle and bridge pier,the inspection of hourglass energy and interface slip energy,etc.According to the energy conservation and impact force comparative analysis,the correctness of the calculation results of vehicle bridge collision is verified.The results show that: nder the impact of vehicles,the stress of the pier develops faster from the impact area to the bottom of the pier than to the top of the pier.The stress in the impact area is greater than that in the bottom of the pier,which is prone to local collapse.It shows that the stress damage area in the process of vehicle bridge collision is mainly the impact area,followed by the bottom of the pier.(2)The finite element models of three kinds of anti-collision devices are established.Firstly,the aluminum foam material,rubber concrete material and foam aluminum outsourcing rubber concrete material are introduced.The types,materials and corresponding parameters of the three kinds of anti-collision devices are determined,and the finite element model of the vehicle anti-collision device pier is established.By construing the process of hitting a pier with three types of anti-collision devices at a speed of 80km/h for a medium truck of 8 ton,the energy change during the collision,the impact force on the pier and the impact depth of the device are compared in this research.It is found that the peak impact force of three anti-collision devices on the pier has been reduced by 28.9%,21.2%,and 23.6%,respectively.Among them,the foam aluminum anti-collision device has the least rigidity,the rubber concrete anti-collision device has the lowest stiffness,while the rubber concrete anti-collision is the stiffest.And the stiffness of the aluminum foam outsourcing concrete is somewhere in between.(3)In order to study the anti-collision performance of three kinds of anti-collision devices under different collision conditions,a series of working conditions are established with the speed of 20km/h,40km/h,60km/h,80km/h,mass of 8t,12 t,16t,eccentricity of 0,0.3m,0.6m,0.9m.A minute study on the energy conversion,impact force and depth as well as the internal energy absorbed by the anti-collision device has been made.The results are as follows: the aluminum foam anti-collision device has the largest reduction rate of impact force,but it has the largest plastic penetration depth and the longest impact duration,followed by the aluminum foam outsourcing rubber concrete anti-collision device,the rubber concrete anti-collision device has the lowest impact force reduction rate,the plastic penetration depth is the smallest,and the impact duration is the shortest.(4)Based on the local sensitivity analysis,the structure optimization of the aluminum foam outsourcing rubber concrete anti-collision device is studied.By changing the material proportion of the aluminum foam and rubber concrete,the width and height of the anti-collision device,the author pays attention to the changes in the maximum impact force,and the maximum impact depth on the pier as well as the energy absorption of the anti-collision device under different conditions.According to the results,it is found that the ration of aluminum foam and the rubber concrete in the anti-collision device is 1:0.5,the width of the anti-collision device is0.6m,the height of the anti-collision device is 2.2m,the foam absorbing aluminum rubber concrete anti-collision device has the best cushioning energy absorption characteristics.The optimized anti-collision device is analyzed,and the dynamic response characteristics of pier such as displacement and stress are studied,which proves that it can effectively protect the pier from damage.