Study On Structure And Performance Of Integrated Guardrail With High Protection Grade Central Separator

The median guardrail is one of the important traffic safety facilities on highways.If its protective capacity is insufficient,it can easily lead to malignant accidents,causing serious casualties and property losses,and having a negative social impact.There is a shortage of land for highway construction in our country,and there is a lot of room for improvement in meeting the requirements of land conservation,strong protective capacity,and aesthetics in the current median guardrail of highways.Therefore,it is of great significance to study a new type of integrated central median guardrail with high protection level.This article categorizes the research and development process of guardrails into six stages:preliminary design,component design,scheme design,structural optimization,performance evaluation,and actual vehicle testing.Based on this,research is conducted on the structure and performance of new guardrails.First,the feasibility of the finite element simulation technology is demonstrated through the theory of computation of barrier collision dynamics,and the parameter setting in the finite element experiment is studied by building a model to ensure the technical rationality of the simulation experiment.Then,based on the concept of Analytic Hierarchy Process,the internal mechanism connection between the finite element simulation experiment of guardrails and the full-scale test of real vehicles was explored.The Cov AHP method was used to compare and analyze a large amount of simulation data and real vehicle collision data,and the guardrail safety performance evaluation equation was calibrated.It was found that the safety score error of both research methods for various types of guardrails did not exceed 5%,which verified the reliability of the finite element collision simulation experiment.To determine the simulation components of the guardrail,a study was conducted on the total height,beam structure,column structure,and foundation form of the guardrail based on mechanical performance principles and design experience.Simulation models for 1.5t small passenger cars,14 t large passenger cars,and 25 t large freight cars were established.Furthermore,based on the research of simulation components,three overall structural schemes of high protection level integrated beam column steel guardrails,namely the SAm level one column two side crossbeam separated central median guardrail,the SAm level one column two side crossbeam combined central median guardrail,and the SAm level one column single track crossbeam independent central median guardrail,were proposed.Simulation collision experiments were conducted on each guardrail,and the results showed that the SAm level one column single track crossbeam independent guardrail had good safety protection performance In terms of economy and construction convenience,it is preferred as the research plan for guardrails.Then,in order to improve the comprehensive performance of the guardrail,iterative optimization of the guardrail structure was carried out based on finite element simulation collision tests,including the connection between beams and columns,component strength matching,beam splicing method,and foundation connection,to improve the optimal guardrail scheme.Finally,according to the SAm level collision conditions,finite element simulation method is used to pre evaluate the safety of guardrail blocking,buffering,guiding functions,and guardrail deformation values.After passing the evaluation,full-scale collision tests were conducted on various types of vehicles in the testing ground to evaluate the actual safety performance of the guardrail.It was found that all indicators of the guardrail met the specification requirements,with a protective capacity of five(SAM)levels and a protective energy greater than 400 k J.Based on the guardrail safety performance evaluation equation and the impact analysis of parking sight distance and lateral clearance,the safety performance evaluation of the guardrail was improved.This thesis studies the reliability of the finite element crash simulation experiment of the guardrail from the dimension of mathematical relationship,and the new type of integrated guardrail with high level of protection central separator has the functions of safety protection,land saving,traffic beautification,convenient construction and installation,and excellent comprehensive performance,which can be safely used in highway,first-class highway and other high-grade highway projects.