Nikulin V. Stress-strain state of light-type floor plates considering initial disadvantages

The dissertation is devoted to the analysis of the stress-strain state of monolithic reinforced concrete overlapping slabs with inserts void-formers that having initial disadvantages. Existing structural solutions of lightweight reinforced concrete structures and their erection technologies have been analyzed in order to assess the feasibility of application of hollow inserts void-formers in monolithic frame construction. The works of the authors devoted to theoretical and experimental research of lightweight reinforced concrete slabs are considered; main advantages and disadvantages of known domestic and foreign systems are considered, in this connection, the goals and objectives of the thesis were formulated. The analysis of the interdependence of the stress-strain state of structures and the sizes of the inserts and their location with the condition of minimizing the consumption of concrete are considered. The problem of optimal cutting of the initial blank of the sheet of void-forming material on the inserts of the required size in order to minimize waste material of the filler is solved. The recommended geometric parameters of the slabs are defined in terms of integrity, fire resistance and reliability. Initial technological deviations that give rise to the design flaws of the systems are investigated and systematized. A numerical analysis of the impact of these disadvantages on the stress-strain state of the system is performed, on the basis of which tolerances are formulated for the deviation of the position of the liners and fittings. Development of self-compacting concrete composition with spill cone of 650mm, which provides concreting in one stage without vibration and tears, and a new structural solution of plastic retainers for liners that prevents the displacement of the liner from the design position are considered. An experimental verification of the proposed structural and technological solution by a field test of lightweight slab of non-residential building using the method of hydrostatic loading is performed. Implementation of the research results is outdone at a number of construction sites in Kharkov. The results of the study confirm the obtained in the theoretical simulation reduction of self-weight of the structure by 40% and the cost of erection by 12.5%.