Vozniuk L. Bearing capacity and deformation of multilayer slabs

The thesis is devoted to the development and research of load bearing capacity and deformability of effective multilayer reinforced concrete slabs with an average layer of light concrete and effective monococcus keramzit concrete slabs. In this work the principles of design are developed and 3D finite-element nonlinear calculation models for all series of experimental samples are formed. As a result of the use of the created calculation models, an analysis of the stress-strain condition was performed and an assessment of the bearing capacity of the multilayer reinforced concrete and monococcus keramzite concrete slabs was performed. It is important that, with their identical bearing capacity and the same supporting conditions, under the action of a static load of their own weight, the frequency of the main tone of the oscillation of the monococcus plate is greater compared to the multilayer at 20 ... 32%, and the deflections are lower by 26 ... 35%, which indicates an increased rigidity of the monococcus keramzite slab. An engineering methodology was developed and an approach to the assessment of the bearing capacity of solid, multilayer and monococcus slabs was proposed, with their support for four corners. Comparison of the results of experimental studies with this technique gave a satisfactory convergence of results with an accuracy of up to 8%. On the basis of the developed principles, a new monococcus keramzite-concrete construction of slab was created. The multilayer reinforced concrete slabs with an average layer of light concrete and monococcus keramzite concrete slabs of overlap have been experimentally investigated. A comparison of the results of experimental and theoretical studies is performed and satisfactory convergence is obtained. The results obtained during the experiment have satisfactory convergence in comparison with theoretical modeling, which confirms the possibility of using the proposed finite element models in real design. The difference between the experimental and theoretical results was: for slabs series 1 - 1 ... 10%, for slabs series 2 - 1 ... 15%, for slabs series 3 - 2 ... 14%. For all types of test boards, the coefficient of efficiency Kef was determined, by which one can compare different structural solutions of overlays taking into account the potential energy of deformation. The monococcus keramzite-concrete cladding slab is 2.1 times more effective than classic solid reinforced concrete slabs and 1.3 ... 1.5 times for multilayer plates developed in this work. The multilayer reinforced concrete slabs with an average layer of light concrete (aerated concrete and expanded clay concrete) have been developed and investigated. In accordance with the efficiency coefficient proposed by the Kef, their efficiency in 1,4 ... 1,6 times is greater than the classical solid reinforced concrete slabs of heavy concrete. Submitted proposals for designing and manufacturing multilayer floor slabs with an average layer of lightweight concrete - claydite and aerated concrete and monococcus keramzit concrete slabs with void inserts.