Annotation

We investigate the zone of pure bending of beam elements of heavy con-crete. The cross-section of the investigated beams is reinforced: in the stretched zone – a strained sheet and non-tension rod, in the compressed zone – a strained and non-tension rods.

The destruction of the research beams occurred on the occasion when the stress in the stretched reinforcement reached the yield point before the stress of the compressed zone was exhausted. Further loading of the samples caused significant deformations in fluidity in the reinforcement, sharp crack opening and increase in deflections, as a result of which the height of the compressed zone of concrete were reduced and its destruction.

Simulation of work in the zone of pure bending of the beam described above was performed on the basis of the deformation technique. The stress-strain relationship for concrete is adopted in the form of a polynomial of degree 5. For the armature, a dependence is adopted with the horizontal upper branch.

Based on the results of the simulation, with loads of the beam first there is fluidity of the sheet reinforcement, then the fluidity of the reinforcement bar of the stretched zone and after this destruction of the compressed concrete zone.

Based on the results of theoretical studies, graphs of moment – curvature, moment -the relative deformation of the upper face, and graph the stress in the compressed zone of the beam at the limiting moment are constructed. The maximum bending moment in the graph of the bending moment - curvature dependence shows the bearing capacity of the beam.

The destruction of a beam due to the destruction of the concrete of the compressed zone occurs on the basis of the calculations at the bending moment of 101 kNm, and according to the results of the experiment – 110 kNm. The difference is 8%.

The deformations of concrete and reinforcement of the beam obtained as a result of the experiment and simulation with the accepted stress-deformation dependencies of the materials agree satisfactorily.