Reliability Analysis Of Concrete Structres Based On Fuzzy Mathmatics

Concrete structure reliability assessment along with the structural reliabilitydesign is an engineering problem to be solved in our country, and it is also one ofthe hot topic in academics and engineering field both domestically and abroad. Atpresent, the assessment method of the reliability in China is still in research stage.Both building standards and regulations adopted by the reliability appraisalbasically belongs to the category of practical survey method. The identificationmethod is developed based on the traditional experience method, and it overcomesthe drawback of the traditional empirical method. At the same time, it makes fulluse of the modern testing instruments and test techniques, reasonably use theknowledge probability theory and mathematical statistics. However, the method canjust evaluate the current status in both buildings, yet fails to give the failureprobability for the existing building which continues to serve. Nevertheless, as thefoundation for the reliability assessment, practical identification method is stillbeing used by China’s relevant standards and regulations.Because the concrete structure reliability evaluation has the features such asthat its target and its influencing factors are fuzzy, that the evaluation model issimple, and that the index system is not complete, therefore, it is difficult to makecomprehensive and accurate evaluation of the safety, applicability and durability ofthe structure. This paper discusses in detail the fuzziness, the fuzzy concept, thebasic concept of relative membership degree, degree, etc. It proposes using thetheory of fuzzy mathematics to make comprehensive evaluation of the reliability ofconcrete structures. First of all, combined with the characteristics of concretestructures, the multi-level comprehensive evaluation model is established. Then onthe basis of the existing research results and experts’ experience, the evaluation ofthe index layer and the project is classified and standardized. The uncertaininformation is represented with the quantitative method, and according to the fuzzyoperation the comprehensive evaluation matrix is obtained. All the levels of thefactor domain and weight along with all the levels of evaluation vectors aredetermined are determined. At the same time, according to the evaluation of thecharacteristics of the project, the hierarchy, the reliability and corresponding membership function is constructed, and evaluation vector. Through acomprehensive evaluation floor by floor of the existing concrete structures, thefinal evaluation of the overall level of reliability of the structure is made. Thispaper takes the teaching building of a vocational technical school in Shanghai as anexample, and evaluates the structure reliability. The final calculation results areclose to the actual situation. It can provide theoretical basis for the structurereliability appraisal.