Study On Application Of Multi-source Information Fusion Technology In Condition Assessment Of Steel Cable-stayed Bridges

In order to ensure the safety,serviceability and durability of long-span cable-stayed bridges,it is very necessary and urgent to establish a scientific and reasonable evaluation system.At present,the cable-stayed bridge assessment sources come from munual inspection in the bridge maintenance management system and monitoring data in long-term bridge monitoring system.However,they all have their own shortcomings and difficult to be the ideal independent data source for bridge assessment.In view of this,the method of multi-source information fusion is applied for integrated assessment of steel cable-stayed bridge.Moreover,data and information from the two systems are integrated to obtain the consistency and reliability of the assessment results,which provides scientific and reasonable maintenance decisions.The main research contents of this paper are as follows:(1)Research on information fusion model of cable stayed bridge.In order to describe the function,relationship and the data flow between the components in the evaluation system,the data information from maintenance management system and long-term monitoring system are integrated.And information fusion function model and system structure for cable-stayed bridge condition evaluation system are designed.Then,relevance between the information fusion and the assessment is explained.In addition,the current status of the two types of data sources of steel cable-stayed bridges is summarized.This makes the foundation for the subsequent data fusion and evaluation.(2)Research on multi-data fusion method.According to the massive amounts of data to be processed from long-term monitoring bridge system,the methods of self correcting fusion and mutual correcting fusion are proposed and a feedback monitoring data processing flow is established.An example is given to verify the practicability of the fusion method.Through the finite element model updating and considering the distribution of statistical methods for the elimination of the environmental loads,feature extraction is performed to obtain the evaluation reference value.The feasibility of the method is illustrated by an example of cable force and mid-span deflection.(3)Research on the further application of data fusion.Three application examples are given.One is used to verify the temperature action types,different temperature actions on a bridge are verifed;second,temperature effects of monitoring data are analyzed.The temperature effect of the cable force and deflection are studied;third,the warning line of the mid-span deflection based on guarantee rate is established.The condition before and after the snowstorm in 2008 and the situation of traffic volume growth are selected to verify the warning line.(4)Research on the index system and the corresponding assessment criteria.According to certain index selection principle and hierarchy structure method,the index system of steel cable-stayed bridge is established.The inspection indicators are divided into three categories:qualitative indicators,quantitative indicators and sequence indicators.For qualitative indicators,a quantitative evaluation method based on detailed description and statistics is proposed;for quantitative indicators,a line model based on the standard is used,and fusion methods of multi-source detection,including two-dimensional fusion,merging and supplementary parameters are put forward;for the sequence index,the comprehensive evaluation method based on grey theory is proposed.(5)Study on the comprehensive evaluation method of cable-stayed bridge based on analytic hierarchy process.Appropriate scale is selected according to certain criteria.The weights are determined by the group weights based on fuzzy clustering method.An improved evaluation method based on analytic hierarchy process is established by improved single component scores and a new classification method of the components number.Taking into account the situation that the traditional weighted calculation method will cover the difference between the indexe,the concept of credibility is introduced,and a multi-index comprehensive evaluation model based on evidence fusion is established.The applicability of the two methods is verified by the inspection of a bridge.(6)Development of a comprehensive evaluation software system for cable-stayed bridge.Using MYSQL database and B/S architecture for the network model,the evaluation software system for cable-stayed bridge is established.It contains database management,data processing,monitoring and inspection,comprehensive assessment,defects diagnosis,maintenance management,print and help and other functions.The eight year inspection records of three cable-stayed bridges are considered as examples to verify the correctness of the evaluation method and the software operation.