Deformation of concrete under long-term influences of different types

Abstract

Introduction: Creep deformation of concrete depends at the character of stress state (compression, tension, bending, etc.). At this moment in our country as well abroad the chief parameter which determine by results of long tests concrete sample is the creep of concrete. These tests are done in the mode of uniaxial compression in spring units for one or several specimens, which simulates the compression of walls and columns. But in addition to centrally compressed elements, bending is present in an important part of structures (extracentral compressed columns, slabs, beams, etc.). In unique and difficult constructions massive reinforced concrete elements (foundations, elements of supports for equipment, columns of the lower floors of high-rise buildings, etc.) are often used. In this case the real work of structures under longterm effect of loading differs at the experimental one. Objective: Design and approbation of these methods to concrete testing samples under conditions other than standard tests - in the bending and three-axial compression modes. Materials and methods: In this scientific article describe the methodology of experimental setup for investigation of creep concrete specimens in the bending mode and in the mode imitating three-axial compression, describes the parameters of testing devices, specimens under test and principles transmission of load. Results: In this scientific article results of the experimental studies are presented in the graphical form in the article; their analysis is fulfilled. Conclusions: The perspectivity of the suggested approaches to the testing of concrete specimens for long-term loads has been shown, and recommendations for changes in GOST 24544 have been prepared.