CALCULATION OF NONELASTIC REINFORCED CONCRETE CONSTRUCTIONS G.S.Aktaukenova 1 , R.T. Turebayeva 2 , 1Expert Scientific Research Institute of the Eurasian National University named after L. Gumilyov (the Republic of Kazakhstan) 2Expert Scientific Research Institute of the Eurasian National University named after L. Gumilyov (the Republic of Kazakhstan) E-mail: [email protected] Abstract In the theory of resistance of reinforced concrete structures it is required to be able to predict and describe the behavior of structures under various conditions and at any time during its existence. Assessment of the stress strain state of the construction must be considered taking into account the random effects of natural and manmade disasters, such as earthquake, flooding, freezing, fire, and others. In this broader sense, this problem can not be solved by methods of linear structural mechanics, as two principles (Hooke's law and the principle of small displacements), laid in its foundation, limit its capabilities. The principle of small displacement is not acceptable under certain loads, and Hooke's law, beginning with a certain level of stress for all materials is no longer maintained and replaced by a nonlinear dependence between stress and strain. It follows that for a careful calculation of the design strength it should be abandon the principles of linear theory and apply more broad and complex justifications of nonlinear theory. In this work the solution to the problem of calculation of inelastic reinforced concrete beams throughout the entire phase of work, from loading until structural failure is introduced. The calculation takes into account sufficiently strict physical and geometric nonlinearity and cracks in the tension zone of concrete. The basic assumptions and the calculation positions, the equivalent module of deformation To make the calculated dependences for determining of the stress strain state and bearing capacity of reinforced concrete cross-section of the element, taking into account nonlinear and no equilibrium deformation of materials, it is necessary to describe the model of the section. Accurate records of forces due to redistribution of elastic-plastic and rheological properties of concrete, rebar inelastic deformation, the formation and development of cracks and changes in stiffness of the cross section leads to complex dependencies [1], almost insurmountable in the numerical implementation. At the first stage of the research of the stress-strain state and bearing capacity of the structures it is preferable to have cross-section model, based on the hypotheses of the mechanics of deformable bodies, which give quite acceptable solutions in nonlinear theory of reinforced concrete. We use the following assumptions. 1. The hypothesis of plane sections for the distribution of the strains. 2. For any fiber b b dependence follows diagram of the fiber axial compression of concrete. Form of the 3 3 A E equation is the same for uniform and no uniform compression (tight area of a flexible or eccentrically compressed element). 3. Concrete is cracked in the stretched zone.
CALCULATION OF NONELASTIC REINFORCED CONCRETE CONSTRUCTIONS
Jun 24, 2023
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