RESISTANCE OF COMPRESSED CONCRETE TO LONG-TERM LOADS

Abstract

This article deals with the main regularities and features of compressed concrete deformation under the action of long-term loads. The main efforts are aimed at establishing an analytical dependence on determining the long-term strength level of compressed concrete. A critical analysis of the currently existing dependencies based on its calculation was carried out. These studies are based on the general provisions and hypotheses of the previously developed energy model of concrete and reinforced concrete deformation.The defining hypothesis of the specific potential energy invariance of the concrete ultimate deformation (destruction) and its independence from the loading mode of the concrete itself was used. The specific potential energy of compressed concrete deformation at the moment of its destruction under three loading modes is considered: instantaneous dynamic, standardized short-term and long-term. The level of compressed concrete long-term strength is related to the dynamic increase factor limit values (DIFu) under the instantaneous loading mode. In turn, the compressed concrete dynamic increase factor is functionally related to the generally recognized coefficient of compressed concrete standardized elastic-plastic properties under a short-term loading regime. In this way, the functional dependence of the level of compressed concrete long-term strength was obtained not only on its standardized elastic-plastic characteristics, but also on the rate of concrete deformation or on the rate of its loading. The evaluation of the proposed methodology for determining the level of compressed concrete long-term strength is reduced to a comparison of the relevant theoretical calculations results with the various researchers’ published experimental data.