Evaluation Of Bridge Technical Condition Based On The Deterioration Model And Cloud Theory

Bridge is the controlled node of the transportation line and its good operation is important to smooth flow of local traffic and economic development,and one of the main aspects of operational management of bridge is the inspection.The bridge technical condition evaluation is the key link and important foundation of bridge operation state maintenance.Theories and methods on evaluation of bridge technical condition are still in the stage of continuous development and improvement,there are some limitations in existing method of bridge technical condition evaluation,while the subjective experience of engineer has great impact on the results.A scientific comprehensive evaluation method with theoretical and engineering value is exigent and valuable to be proposed,which established the perfect valuation index system of bridge technical condition,allocated the reasonable index weight,divided the structure to evaluate grade.Therefore,a study aiming at reasonable bridge technical condition evaluation has been accomplished in this paper.The deterioration model and cloud theory were used in evaluation of bridge technical condition,a perfect index system of bridge technical condition evaluation was established by uncertain type of analytic hierarchy process to determine the index weight and cloud theory evaluation method to divide bridge technical condition rating,indicators were transformed from qualitative to quantitative.Cloud gravity evaluation method of bridge technical condition was established finally.The main work of this paper includes the four aspects:(1)Based on natural degradation piecewise nonlinear model of the initial technical condition of bridge formation and the previous year bridge technical condition,a nonlinear model considering the parameter λ which identified the degradation of bridge technical condition was built.The bridge life process was summarized,and the main factors of bridge life termination criteria were investigated based on large quantities of engineering test data statistical analysis.(2)Evaluation criteria and index system of bridge technical condition was established and 2 grade indicators of bridge technical condition with the multi-level factors which influencing the bridge condition was proposed.The weights of evaluation indexes by adopting the method of uncertain analytic hierarchy process was determined.Based on dynamic load analysis,geometric analysis and vibration theory analysis method,the method of identify the traffic load based on dynamic strain was proposed,the monitor method of curves continuous beam bridge climb shift and the short cable tension measurement method based on additional mass were present and verified.The probability density evolution method of chlorideion concentration distribution was established based on parameter analysis,which could evaluate the condition of concrete bridges in chloride environment.(3)The bridge technical condition score and grade boundaries were represented by cloud atlas in current criterion,the golden section method was used to calculate the classification limit of the score region of bridge technical condition,then the cloud-parameter and the technical condition cloud atlases of diffident bridge condition were given.Then,the multiple clouds synthesis of bridge technical condition was discussed based on the floating clouds division similarity.Based on evaluation method of cloud theory and considered the randomness and fuzziness of cloud model,the bridge technical condition indicators were transformed from qualitative to quantitative.(4)The bridge technical condition was divided into five cloud atlases and the evaluation model based on cloud barycenter evaluation method was established.The weight deviation method was used to measure the technical condition of bridges so as to constitute the mutual mapping between the qualitative and quantitative evaluation.As for randomness and fuzziness of bridge technical condition index information,bridge condition index system was a combination of qualitative and quantitative.Finally,the feasibility of the method posed by this paper was verified through the practical engineering application.The research results of this paper could provide methods and basis for both bridge technical condition evaluation and the revision of related specifications and standards.