USING IMPROVED DESIGN METHOD OF SHEER STRENGTH OF REINFORCED CONCRETE BEAMS
Journal Title: Вісник Національного університету "Львівська політехніка". Серія "Теорія та практика будівництва" - Year 2019, Vol 0, Issue 912
Abstract
The analysis of the efficiency of six types of slabs has been carried out, which differed in material, internal form and weight. The comparison and the comparison of the same in size, but different in constructive characteristics and materials of floor slabs are considered and performed. namely: I – solid reinforced concrete; II – multilayer reinforced concrete with a middle layer of expanded clay concrete; III – multilayer reinforced concrete with a middle layer of aerated concrete; IV – monocoque reinforced concrete with void forming inserts from PPS; V – solid claydite; VI – monocoam keramsite concrete with void-forming inserts from PPS. It was established that the monocoque slab made of expanded clay was the lightest of all types of slabs, in particular, from solid reinforced concrete in 2.4 times, and from solid claydite concrete in 1.4 times. Compared to the classic solid reinforced concrete floor, concrete savings of 40 % have been achieved. According to the thermal characteristics, monolayer expanded concrete slab was best shown, because its heat transfer resistance is 4.3 times higher than the classical concrete slabs and 2.8 times for solid concrete clay. The main material of the monocoam floor slab was claydite with the following physical and mechanical characteristics: compressive strength not less than 21 MPa, volumetric mass 1800 kg / m³. The upper and lower shelves of the plates were joined together by the transverse ribs, which were reinforced with welded reinforcing frameworks. The upper and lower shelves were reinforced with welded nets. The technology of manufacturing of effective monocoque lightweight floor slabs has been developed and implemented taking into account the features of the existing technological lines of the existing factory of reinforced concrete structures ZBV №2 in the city of Lviv. The block diagram of the production process is formed. The sequence of concreting and reinforcement of structures taking into account all the structural features of the slabs is gradually described. Concreting was carried out in two stages. At the first stage, after the fitting of the fittings, the concrete of the lower shelf was inserted, and on the second, after 30 minutes, after the installation of foamed polystyrene inserts and upper fittings, concrete work ribs and upper shelf. As a result, the construction of monocoque slabs with the same, in comparison with solid monolithic, external dimensions, but which by their characteristics are much more effective than the classic. The test of the plates confirmed the correctness of their manufacturing techniques associated with a 30-minute break in the mix by inserting an effective middle layer and pouring concrete ribs and upper shelf. This technology has ensured the co-operation of all layers during the test.
Authors and Affiliations
L. I. Vozniuk, B. H. Demchyna, M. I. Surmai, V. V. Artemenko
Keywords
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