Fuzzy Comprehensive Assessment Of A Concrete Beam Bridge In Baoding

Accompanying the continuous progress of China's economic level,the average daily traffic volume in terms of highway transportation has not only increased significantly,but also the tremendous pressure it brings to bridges has led to various diseases and defects of bridges,and there are a large number of potential safety hazards in the use of bridges.Consequently,it is of significant engineering importance to inspect and evaluate the condition of bridges in service.In this paper,a comprehensive assessment system for the condition of a concrete girder bridge in Baoding is constructed based on the on-site inspection of the bridge using hierarchical analysis and fuzzy comprehensive assessment method.The main conclusions are as follows.?1?Determine the evaluation indicators of the evaluation system and establish evaluation sets and factor sets according to the disease and structural characteristics of bridges.A comprehensive assessment model of the condition of concrete girder bridges is constructed by using hierarchical analysis from the perspective of influencing the safety,serviceability and durability of bridges,taking into account the structural characteristics of bridges.The group decision method and variable weighting method are used to calculate the initial weights of the factor indicators at each level,and the fuzzy theory is used to determine the affiliation functions and evaluation criteria of the bridge factor indicators.?2?Appearance inspection,non-destructive inspection and load test of a beam bridge in Baoding City.Record and sort out the diseases of the bridge,and conduct non-destructive testing for some important parts or damaged components,including:concrete strength,concrete carbonization,steel corrosion,concrete protection layer thickness and chloride ion content testing,and determine according to the membership function and evaluation criteria its rank.After static load tests on site,the strain and deflection values in the control section of the structure are tested,and the analysis method combining theory and practice is used to verify whether the bridge structure meets the design requirements of the specification;the inherentness of the bridge structure is measured through the dynamic load test Frequency and damping ratio to detect whether the dynamic performance of the bridge is intact.?3?The initial weights are variable weighted according to the bridge inspection data,combined with the evaluation criteria and affiliation functions of the bridge evaluation indexes to obtain their respective grade evaluation vectors,and the variable weighted integrated evaluation method is applied.The bridge's condition is evaluated by multi-level fuzzy comprehensive evaluation calculation,that is,A=?v₁,v ₂,v₃,v₄,v₅??28??0.58,0.35,0.05,0,0?.In accordance with the principle of maximum affiliation,the maximum value of ₁v?28?0.58 is selected,that is,the comprehensive condition of the bridge is assessed as?,a class of bridge.The results are consistent with the current national norms,which demonstrates that the fuzzy comprehensive assessment system established in this paper is appropriate for actual engineering applications.