Fuzzy Comprehensive Evaluation Study For Existing Bridges

As time goes on, existing bridges are functionally obsolete and aging and sufferaccumulatively serious structural damage. It has become difficult for them to adapt to thestill growing traffic volume. They have become the bottleneck to transportation, restrictingthe rapid development of China’s economic construction. Even some bridges have collapsed,resulting in huge losses to people’s lives and property safety. Therefore, in order to ensurethe smooth traffic of highways and create safe and comfortable driving environment,regarding how to make reasonable and accurate assessment of existing bridges, it hasbecome the focus in the engineering field.In this paper, existing highway bridges were research objects. The status of existingbridges at home and abroad and bridge evaluation was analyzed, and the urgency andnecessity of evaluating the status of existing bridges were pointed out.Fuzzy set theory and fuzzy comprehensive evaluation theory were elaborated andsummarized. The methods and process of fuzzy comprehensive evaluation applied to bridgestructure were also introduced.According to characteristics and damage features of bridge structure, bridge structurewas divided into layers and several subsystems, and bottom evaluation indicators of eachsubsystem were determined, the fuzzy comprehensive evaluation hierarchical model ofbridge structure was established, evaluation standards of bottom indicators were also givenby combining specifications and related literature, and evaluation set vectorsV={v₁, v₂, v₃, v₄,v₅} which were consistent with specifications were determined.Indicator weight of each bridge layer was determined by Analytic hierarchy process（AHP）. Compared each layer of indicators in pairs by the method of any interpolation among1⁹. The judgment matrix has good consistency. Reasonable weight distribution has beenobtained by calculating the characteristic vector of the maximum characteristic value.The load test of Baotou Yellow River BridgeⅠwas analyzed and summarized,conventional comprehensive evaluation and fuzzy comprehensive evaluation of this bridgebased on bridge inspection and test results were also carried out. The final score by conventional comprehensive evaluation is Dr=56.6, so it is a bridge of the third type; fuzzyevaluation set of this bridge is （0.140,0.293,0.376,0.171,0.020）, and then this bridge is in aquite poor state of the third type according to the maximum membership principle andweighted-average method. Results by both evaluation methods have been consistent, provingthe applicability and effectiveness of fuzzy comprehensive evaluation method for bridgestructure in this paper.