Research On Safety Risk Assessment Of Small And Medium Beam Bridges In Northwest China

With the development of highway network construction in China,the number of highway Bridges is continuously increasing.At present,a large part of Bridges in service in our country are "serving in spite of illness",especially in the areas with bad service environment,their use function can no longer meet the requirements of the original design,and even lead to safety accidents,resulting in the loss of people's lives and property.The key problem to solve this situation is to carry out safety risk assessment on the bridge in service in this area and carry out maintenance and reinforcement of the bridge according to the assessment results.Because of the bad environment in northwestern China,bridge diseases in service is more,and because the area of highway bridge in small and medium-sized girder bridge is given priority to,so this article selects northwest dry cold area small and medium-sized bridge as the research object,complete the evaluation theory and evaluation method of research,identify the type of bridge main diseases,establishing evaluation index system,evaluation model was constructed and a series of specific work,and the technical condition of this kind of bridge operation during the accurate and objective judgment.This paper mainly includes the following four parts.In the research stage of the theoretical knowledge of bridge safety risk assessment in service,combining with the previous research results,this paper expounds the relevant concepts of risk and bridge risk,and defines the process of bridge safety risk assessment in service.In this paper,the content of in-service bridge safety risk assessment is further studied,which is described from two aspects of assessment theory and assessment method.By comparing and analyzing the advantages and disadvantages of various evaluation methods and combining with the characteristics of in-service bridge safety risk evaluation,the fuzzy comprehensive evaluation method is selected as the research method in this paper.Assess risk recognition,the collected data of Gansu province 155 small and medium-sized bridge diseases were analyzed,combining with the characteristics of bridge structures,and the northwest dry cold regional environment characteristics,summarizes the region bridge common disease types,emphatically from the factors of service environment,analyze the forming mechanism and cause of common diseases;By means of mathematical method,the probability distribution and its distribution function of common diseases are obtained,and the rationality of the selected samples is checked.A comprehensive and reliable safety risk evaluation index system for small and medium-sized beam Bridges in northwest dry and cold regions was established based on the common diseases of small andmedium-sized beam Bridges in northwest dry and cold regions.In the construction of evaluation model stage,based on the general operation steps of fuzzy comprehensive evaluation method to solve practical problems,and combining with the safety risk evaluation index system of small and medium-sized beam Bridges in northwest dry and cold regions,the safety risk evaluation model of small and medium-sized beam Bridges in northwest dry and cold regions is constructed.In the application stage of engineering example,this paper selects a beam bridge in Gansu province as a case,according to the established evaluation index system,and collects the required data through on-site detection of each evaluation index.The data is brought into the constructed fuzzy evaluation model of safety risk for calculation,the safety risk evaluation of the bridge is completed,and the corresponding risk countermeasures are given according to the final evaluation results.Through to the northwest dry cold region of small and medium-sized bridge safety risk assessment research,feasibility and reliability for this type bridge is given a high security risk evaluation method,by using this evaluation method of Bridges in service after the security risk assessment,and according to the evaluation of bridge risk level,formulate the corresponding risk control measures;All the researches in this paper aim to evaluate the technical status of Bridges more accurately,provide more reliable reference information for bridge managers to maintain Bridges,ensure the safety of bridge operation,and minimize the loss caused by bridge accidents.