RELIABILITY OF CALCULATION OF FLEXIBLE REINFORCED CONCRETE ELEMENTS ARBITRALY FIXED TO SUPPORTS USING THE “REAL CURVATURE” METHOD

The determination of the load-bearing capacityof flexible prestressed (including guncrete) elementsarbitrarily fixed to supports, taking into accountsecondary effects, is not regulated by the currentbuilding codes of Ukraine. For materials in which thework diagram is curvilinear, loss of stability can occurboth for a short eccentrically compressed reinforcedconcrete element and for a bending element. In addition,it is known that the prestressing of reinforcementsignificantly affects the increase in the load-bearingcapacity of flexible elements, but the current regulatorydocuments do not contain information about whetherit is possible to take into account the prestressing of thereinforcement in the calculation.This affects the accuracy of determining the criticalforce and, accordingly, the reliability of flexibleeccentrically compressed reinforced concrete elementsand buildings in general. We proposed “real curvature”method, based on physically substantiated premises,operates with fairly simple analytical dependencies andallows us to determine the load-bearing capacity offlexible elements of rectangular, round, ring, I-beamand guncrete sections, taking into account prestressingreinforcement with virtually no limitations in calculatedlength, cross-section, degree of reinforcement, concretestrength, etc.The article evaluates the accuracy and reliability of thecalculation apparatus using the “real curvature” methodof flexible eccentrically compressed reinforced concreteelements arbitrarily fixed at the ends. To assess theaccuracy and reliability, a comparison was made of theload-bearing capacity of 76 flexible reinforced concreteelements, determined based on the use of averageexperimental and calculated values of the strengthand deformation characteristics of the materials. Forcomparison, the results of experimental studies bydifferent authors were used. In these experiments,the following changes were varied over a wide range:flexibility, strength of concrete and reinforcement,percentage of reinforcement, and section geometry. Acomparison was made with the results of calculationsaccording to Eurocode 2. It was shown that thecalculation apparatus fairly well reflects the simulatedprocess, which has a sufficiently high accuracy and thenecessary reliability.