Technical Condition Evaluation Method Of Flexible Suspension Bridges Based On The Appearance Inspection

Flexible suspension bridge is the bridge which has no stiffening girder or a smallstiffness of the girder. The main structures of the bridge contain cable support tower,foundation, main cable, anchorage, suspender, wind cable and bridge decking. It is widelyused in the western and southeastern area of our country; however, the reasonable technicalcondition evaluation method is lacked in this kind of bridges..On the basis of the appearance inspection of more than50flexible suspension bridges inTibet area, the basic parameters of flexible suspension bridges are investigated, the commondiseases and damaged areas of the bridges are summarized on the basis of the statistics, andthe reasons of the damage are analyzed; Moreover, the flexible suspension bridge is dividedinto three parts: superstructure, substructure and bridge decking according to its structuralcharacteristics. And the weights of the component parts of the bridges are widely investigatedby meaning of accepting the suggestion of specialists’ advice. In the process of investigation,the analytic hierarchy process and the clustering methodology are used to deterimine theweight of each part. In the end, the technical condition evaluation methodology is proposedand the evaluation process and standards are made.The standard process of the comprehensive estimate methodology is: firstly, dividing thebridge into three parts: superstructure, substructure and bridge decking according to itsstructural characteristics, secondly, making a judgement: if the evaluation index satisfyanyone of the single control indexs of the bridge technical condition of fifth class bridge, thenmake it as the fifth class bridge; if not, calculating the score of the members on the basis ofthe evaluation standard of each member and determining the coefficient of the structure;thirdly, determining the score of each component; fourthly, deterimining the socres of thesuperstructure, substructure and bridge decking; finally, getting the technical condition scoreof the bridge and its classes.At last, two bridges are evaluated based on the method mentioned before. The resultsshow that the comprehensive estimate method is accurate and easily to be operated, which canguide the maintenance work of the flexible suspension bridges.