Research On The Condition Assessment Of Bridge Based On The Chaotic Time Series

Bridge structures are commonly affected by the factors of natural environment, the increases of traffic, the vehicle load and internal material. As time goes on, defect and diseases may appear, which make the bearing capacity and the durability of structures reduce and affsect the using life of bridge. At present, the evaluation research of bridge structure in service has become one of the hottest research direction of civil engineering area. Bridge load test has the positive significance before new bridge put into use or safety assessment during the bridge harmed accidental. However, bridge load test need to Interrupt traffic and spend a lot of human, material and financial resources. It's costs are relatively high and only applicable to certen stage, at the same time,existing problem of poor timeliness. Remote monitoring of bridge can overcome the disadvantages and has the characteristics of security, real-time, continuous and warning forecast timely.With the technology of structural health monitoring development rapidly,the accuracy of information testing improved and the site test conditions improved obviously, it provides the necessary support for the assessment of the bridge structure status. This paper start off the essence of the nonlinear dynamic behavior of bridge structure, In the basis of mastering a lot of monitoring information, through extracting the characteristics of the system,aims to realize the condition assessment of in service bridges structure. The paper mainly contains following aspects:(1) Collect the research material in the aspect of structure condition assessment at home and abroad.and summarizes the state evaluation theory and methodology systematically. Introduces the basic theory of chaos time series and discusses the method of definition chaotic system characteristic parameters and their calculation for bridge structures. According to the characteristics of dynamic system, put forward applying the chaotic time series theory research the state of bridge structure for the first time.(2) Through analyzing a lot of bridge health monitoring information, put forward data singularity detection methods of the time sequence of bridge health monitoring and the denoising method of time series. Eliminate the interference and noise confounding in monitoring signals, make it reductb practical vibration signal truly,for the below bridge health monitoring time series analysis provide reliable data.(3) Applying the chaotic time series theory and its analysis metod, analysis and research the structure of health monitoring information of Ma Sang xi and Benchmark ASCE bridge respectively, based on the structure of health monitoring information on the bridge structure system analysis and nonlinear characteristics and chaotic time series of the characteristic parameters and its algorithm.Combination of Matlab7.0 procedures, analysing numerical, to get the system characteristic indexes. Experimental results show that:ASCE Benchmark structure and chongqing MaSang xi bridge structure system's biggest Lyapunov exponential correlation dimension greater than 0 and outside-rolling are not an integer and greater than 2. According to relevant theory, explain that the system exists chaotic phenomenon; Maximum Lyapunov index and sample quantity and time delay all have certain sensitivity, andλmax,D2 may change with the structure change and evolution,at the same time,it has the ability of identify structure state.Through numerical simulation and practical bridge respectively, verify the application based on chaotic system characteristics are in service of long-term health monitoring bridge structure condition of techniques used to evaluate the feasibility and availability. This paper presents the method of operation condition of large-scale bridge safety condition assessment has certain reference.