METHOD AND RESULTS OF EXPERIMENTAL RESEARCHES OF CONCRETE CONCRETE MECHANISMS WITH MIXED ARMORATION FOR SHORT-DOWN LOADING

Abstract

The research of reinforced concrete beams with mixed reinforcement for short-term loading of the load was performed for the purpose of studying the stress-strain state, changes in the deflections of the middle of the passage, the dynamics of the crack opening and the possible slipping of the reinforced reinforcement in the concrete. Two samples of beams, 10x10x200 cm in size, reinforced with pre-stressed reinforcement with a diameter of 12 classes A-ІІІ_V, and a non-elastic armature of A-III class 12 diameter, placed in the middle of the span and torn in accordance with the material of the material, were made for the research. The transverse and longitudinal mounting fittings are made with a diameter of 5 mm from VR-I. The tests were performed according to the scheme of a single-span hinged beam, loaded in the tertiary span by two equal lumped forces. Investigation of the stress-strain state of beams samples revealed the following features of their work:

                - up to the time of the occurrence of cracks in concrete (η≤0,5) there was a slight development of deformations of concrete and stretched armature. Concrete of the compressed and stretched zone, as well as the working fittings deformed together;

                - the appearance of normal cracks at η> 0,5 redistributed the effort from the concrete of the extended zone, which crossed the cracks, to the working armature, which led to rapid growth of deformations and bending of beams, as well as to reduce

   - in the range of stresses 0.5 ≤ η ≤ 0.7 there was observed a slower growth of concrete deformations, as well as a decrease in its height in the compressed zone;

                - at a voltage level η> 0,7 there was accelerated development of deformations of concrete, stretched armature and deflections, there was a sharp decrease in the height of the compressed zone of concrete, indicating the onset of the process of fracture and fluidity of the fittings;

                - slipping of reinforced concrete in concrete was not detected.