FEATURES OF CALCULATION OF BUILDING STRUCTURES WITH TRANSFER OF PRESTRESSING FORCES ONTO CONCRETE MIX

Abstract

The study considers and analyzes pre-tensioning and post-tensioning methods of prestressing reinforced concrete structures known in the world construction practice. It identifies reserves for increasing the strength of structures made using these methods. The paper examines the author’s method of prestressing reinforced concrete structures onto concrete mix that allows for significant strengthening of concrete and, depending on structures, provides their increased durability. A paradoxical thing has been revealed – there is stress in the reinforcement of the structure, but there are no corresponding deformations of the elastic compression of concrete, although the reinforcement is fixed in the concrete by adhesion. The paper investigated deformation properties of concrete mix and concrete under the conditions of compression. It has determined that the traditional understanding of reinforced concrete as a material consisting of concrete (artificial stone material) and reinforcing steel does not fully reflect the reality as to the proposed method of prestressing. It was found that when the reinforcement is tensioned and the prestressing forces are transferred, it is not concrete as a stone material that is compressed, but the concrete mix, i.e. the mix of its components (crushed stone, sand). Since there is no concrete yet, the prestressing forces are received mostly by solid components of the mix (according to the technology, water has the ability to be removed from the mix by compression). Thus, compression deformations of the components of concrete mix fully correspond to the force in the reinforcement. The law of conservation of energy and Hooke’s law, of course, also apply to the following structures with during-tensioning onto the concrete mix. Here we deal with the phenomenon of the transition of the external compression energy into the internal bond energy during the phase transition of the concrete mix to the solid state. The paper develops major approaches to the calculation of reinforced concrete structures with during-tensioning onto the concrete mix; the approaches take into account the transfer of prestressing forces to the concrete mix, strengthening the concrete of the structure by pressing.