THE CALCULATING METHOD OF CRACK RESISTANCE AND RIGIDITY OF REINFORCED CONCRETE COMPOSITE CONSTRUCTIONS UNDER THE ACTION TORSION WITH BENDING

The article is devoted to the development of calculating methods of the crack resistance and rigidity of reinforced concrete composite constructions under the action torsion with bending. It is based on proposed classification of discrete cracks and working assumptions, which allow to adjust the rigidity parameters noticeably. It is proposed a new classification of spatial base cracks in reinforced concrete composite constructions which based on an in-depth study of nature of the crack formation. This classification is based on the geometric, force (deformational) and interspersed concentration of the stress-strain state with the corresponding sources-concentrators. The double console models have been constructed to analyze the resistance along the path of crack and along the seam between different classes of concrete; models of level crack appearance, which allows to search for the distances between the cracks and the width of their opening and to display the multilevel crack development process. The block calculation model of the first level with a complete picture of the cracks and their projections to the horizontal axis in the form of a function of many variables is proposed; the stress-strain state of the calculated cross-sections was determined with the help of the software complex "Lira-CAD". This model takes into account the effect of disturbing the continuity of concrete, the incompatibility of the deformations of concrete and reinforcement and intermediate perturbation in the joint between the concrete. The width of the crack opening is analyzed along the entire profile of the crack; the change in the distance between the cracks l _crc and the change in crack length h _crc is taken into account as the load increases (with verification of the multilevel formation process) under various static schemes, reinforcement characteristics, prestressing, various classes of concrete. The algorithm of calculation provides the construction of a complete picture of crack development and their opening, according to the proposed classification; the determination of the distance between the cracks and the width of their opening, as well as the projection of contiguous cracks on the horizontal axis.

reinforced concrete composite constructions, spatial cracks, rigidity, crack resistance, classification and models of cracks, effect of disturbing the continuity of concrete, disturbance in the seam between the concrete and between the main reinforcement and concrete, two-element cantilever models, models of level crack appearance, width of the crack-opening, distance between cracks, calculation algorithm, projection of cracks on the horizontal axis, function of many variables, block model, the surface of a spatial crack, calculated cross-sections, software complexes

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