Simulation Analysis And Study On Improvement Of Protective Performance Of Concrete Guardrail Of Existing Bridge

As an important protective facility in road traffic,highway bridge guardrail plays an important role in protecting occupant safety and preventing traffic accidents.In recent years,with the development of social economy,great changes have taken place in the traffic situation,and the construction norms and evaluation standards of road traffic safety facilities have also been upgraded and reformed.A large number of existing bridge guardrails have been unable to meet the protection needs.Due to the complexity and diversity of bridge structure types,guardrail structure forms and their connections,the protective ability of bridge guardrails is also different.It is more and more difficult to unify the improvement and transformation of its performance.Therefore,it is particularly important to improve the protective performance of existing bridge guardrails.The real vehicle crash test has high cost for evaluating the fence protection performance,and the finite element numerical simulation is an efficient and convenient way.Based on a national and provincial trunk line guardrail upgrading project in Liangshan Prefecture,this paper studies the reconstruction scheme of concrete guardrail and the reconstruction scheme of stone arch bridge local anti-collision system,simulates and analyzes the collision process between vehicle and guardrail,and analyzes the protective performance of guardrail after upgrading.The main work is as follows :(1)The current situation of the guardrail structure of existing bridges was investigated.Combined with the guardrail upgrading and reconstruction project of a national and provincial trunk line in a certain area of Liangshan Prefecture,the insufficient protection ability,especially the lack of resistance caused by the structural defects and connection modes of the guardrails of stone arch bridges and concrete bridges are investigated and studied,and the protection performance is evaluated.(2)In view of the weak connection between the stone arch bridge guardrail and the arch structure,the reinforcement system of the local reconstruction scheme of the stone arch bridge guardrail is studied,and the concrete and steel structure of the insufficient height guardrail are improved.The Hyper Works and LS-DYNA software are used to establish and calculate the finite element model of the above scheme.Combined with the safety performance evaluation standard of highway guardrail,three models of small buses,medium buses and large trucks are selected.According to the collision energy requirements of SB grade guardrail,the collision simulation of automobile and guardrail is carried out,and the protective performance of guardrail is analyzed.(3)The analysis results show that the two types of elevated guardrails meet the requirements of SB grade guardrail protection,and the guardrail has good crashworthiness.All vehicles did not overturn,ride,cross the guardrail,vehicle damage did not hurt the seat position;Under the collision of small buses,the occupant acceleration meets the relevant requirements;Medium and large vehicles did not break the guardrail,guardrail components did not break into the vehicle interior.(4)In terms of guardrail orientation,concrete heightening guardrail scheme is superior to steel structure heightening guardrail;On the degree of damage,under the most unfavorable conditions,the two guardrails have different degrees of damage.The damage degree of the two guardrails under the collision of medium-sized buses is greater than that of large trucks.The deformation of steel structure heightened guardrail is greater than that of concrete heightened guardrail.Considering the maintenance of local mountainous areas,concrete heightening guardrail is preferred.(5)The finite element simulation of guardrail collision is carried out for the reconstruction scheme of local anti-collision system of stone arch bridge.The results show that the reconstruction scheme of local anti-collision system of stone arch bridge can effectively ensure the good connection between the superstructure of bridge and guardrail after collision.Adding galvanized steel pipe in the guardrail foundation has a certain strengthening effect on the guardrail lifting,but the effect is not very significant.