Pershakov V. Creation effect type reinforced concrete frames with bearing elements of variable section

The purpose of the thesis is the experimental and theoretical research, generalization and development of theoretical provisions in the solution of scientific and technological problems of designing, calculation of reinforced concrete elements of I-shaped variable cross-section frames of low power-intensive buildings. Peculiarities of calculation methods, designing and experimental research of three-hinged reinforced concrete frames are provided. It has been established that calculation of three-hinged reinforced concrete frames necessitates taking into account physical and geometrical nonlinearity of construction works as well as the impact of girders and bars deflections under loading. Grounding of loading design schemes and improvement of calculation procedure of three-hinged frames for skeleton buildings for durability, rigidity and crack stability given the deformed scheme, geometrical and physical nonlinearity should be performed using PC LIRA. The choice and grounding of effectiveness of built-up and whole half-frames, class of concrete, shape of girders and struts sections of half-frames have been also made. New constructive solutions of effective reinforced concrete frames of variable section and their units have been developed as inventions. There have been improved and introduced a variety of techniques of experimental and theoretical research, calculation for durability, stability, rigidity and crack resistance as well as determining effective sizes of I-section frames, which allows for designing reinforced concrete structures of low power-intensive buildings, reducing concrete and metal consumption as well as operational costs. A new technique of manufacturing I-section frames elements and their mounting according to copyright certificates has been developed. Experimental research has been carried out and technique of frames calculations for durability, stability, rigidity and crack resistance has been specified. The obtained results of 42 frames calculation using PC LIRA and their comparison with experimental data show that discrepancy between experimental and calculated data on durability and deformation makes up about 10 %. Recommendations on the improvement of half-frame design and manufacturing technology, which lead to the reduction of cracks width, are given. There have been developed working drawings and nomenclature of 24 grades of whole and built-up reinforced concrete half - frames РЖ and РЖС for skeleton buildings of 18 and 21m width premises height 3.3 and 3.6m under standardized loadings 7.5, 13.5, 16.0 kN/m taking into account different options of coverage. Experimental research has been carried out and the technique of designing new multi-span and blocked frame skeletons; designing new constructions of coverage, walls and foundations of frame buildings developed as inventions has been improved. The peculiarities of designing frame skeletons of hall premises of rural public buildings as well as buildings and constructions of agricultural aviation aerodromes are specified. The method of designing low power-intensive reinforced concrete constructions has been developed.