Study On Safety Warning Of The Existing Bridge In The Arid And Cold Region Of North-West China

With the development of road transport industry, bridges were put into use and affected by traffic and environmental loads. So, make the material degradation, crack initiation and development. Resulting in the carrying capacity reduced significantly and threating to the safe operation of the bridge seriously. The effective way to respond and slow the disasters are usually in early warning and prevention. So, it is necessary to carry out research on security early warning of bridge. Taking the arid and cold region of North-West China of existing bridge as the object and Using the fault tree of gray correlation analysis method. Based on warning, building the warning system to determine the total value of early warning. Then,according to the division of alert limit determine the warning degree. And send the warning signals to reduce accidents.First, analysis the main problems exist in terms of safety. In order to find some typical disease, the appearance inspection is an essential part of early warning work by the《highway bridge conservation norms 》. Combined with 《 highway bridge carrying capacity detect evaluation procedures 》《Highway Bridges technical condition assessment standards 》,starting from the main factors affect the safety of the existing bridge member, the safety factors diagram is established. Then analysis the each appearance of disease manifestations,causes and impact of the existing bridges. From the survey analysis to the disease of bridges in Yongchang to Shandan scetion of Lian Huo highway, identified the main diseases were from piers, abutments, bearings, beams, bridge deck etc. nine member. Then use the mathematical statistics to estimating and testing the nine members of the probability distribution of the disease.The warning theory include the elements, theoretical framework and features of early warning system. Drawing the warning system work flow chart and introducing several common ways of warning limit and warning degree. Then focuses on the meaning of majority rule, half of principle, mean the principle by systematic approach that needed to be adopted to prepare for the following warning research.Selected by the principle of early warning indicators and combined with the main factors of existing bridges in Chapter two, the security warning index system will be build by the analytical of object properties method and the variables of principal component analysis filtering. Based on warning, the early warning indicators converted to the form of fault tree.Using the fault tree of gray correlation analysis method to determine the total value of early warning. Based on majority rule, half of principle, mean the principle to determine a limit of respectively by systematic approach and GARCH model. Combined with lessons learned,established standards etc. According to "the degree of risk", the degree will be divided into no warning, light warning, heavy warning, giant warning. Then, according to the division ofalert limit determine the warning degree and send the warning signals. In the case of different warning degrees, the corresponding measures will be proposed.At last, for the K2077+433 Yongshan reinforced concrete beam bridge in Lian Huo highway, with early warning model to research and send the warning signals, drawing the warning signal figure. By investigating the actual countermeasures of the construction site,the early warning results are basically in line with the actual situation.Based on the fault tree and the gray correlation theory, analysis correlation between the various failure modes. On the basis of quantitative analysis combined with qualitative analysis can evaluate the develop trends of the existing bridges in arid and cold region of North-West China and warning. Thus aware of the security situation fully. And the corresponding measures will be proposed at the same time to keep normal operations.