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Composite steel-reinforced concrete frame-monolithic buildings integrate the advantages of combined work of concrete and rigid reinforcement in the form of steel profiles. The combination of steel profiles, concrete, and reinforcement bars has several advantages compared to conventional reinforced concrete structures, particularly in the construction of high-rise buildings, allowing for increased strength and stiffness of structural elements and overall load-bearing capacity with significantly smaller geometric dimensions of cross-sections. The development of information technologies for structural analysis, including finite element methods using 3D finite elements in linear and nonlinear problem formulations, as well as building information modeling technology, enables the investigation of complex cases of interaction between steel rigid reinforcement, concrete, and reinforcement bars, including in the nodes of steel-reinforced concrete frame-monolithic buildings, and allows for designing cross-sections in a 3D information model with subsequent generation of construction drawings. In this study, using information technologies for structural analysis and building information modeling, the stress-strain state of nodes is investigated in both linear and physically nonlinear problem formulations, taking the example of a 25-story steel-reinforced concrete frame-monolithic building. Specifically, the node connection of tubular concrete columns at the outer row at the level of the floor above the first level with an external steel shell in the form of a tube 630x15 is examined in three variants: tubular concrete columns (variant 1), tubular concrete columns with rigid reinforcement by cross steel strips (variant 2), tubular concrete columns with rigid reinforcement by cross I-beams (variant 3). Based on the results of nonlinear analysis, for the variant with tubular concrete columns without additional reinforcement, a redistribution of internal forces in the columns compared to linear analysis is observed. Particularly, there is an increase in stress magnitude in the external steel shell by approximately 24.54% and a decrease by about 66.34% in the concrete core of the columns. However, in the presence of additional steel rigid reinforcement, such redistribution, including the increase in stress magnitude in the steel elements of the columns, does not occur. The average redistribution of bending moments in the floor slabs amounted to 29.7%. An analysis of stress values in the steel shell and steel rigid reinforcement of the columns obtained from nonlinear analysis confirms a tendency for their decrease with increasing magnitude of steel rigid reinforcement, ranging from 326 N/mm2 (for variant 1) to 255 N/mm2 (for variant 2) and 216 N/mm2 (for variant 3).
Adamenko et al. (Thu,) studied this question.