Stiffness of Reinforced Concrete Structures Under Bending With Transverse and Longitudinal Forces

Abstract

The authors developed a model for single reinforced concrete strips in block wedge and arches between inclined cracks and approximated rectangular cross-sections using small squares in matrix elements. From the analysis of the works of N.I. Karpenko and S.N. Karpenko the "nagel" forces in the longitudinal tensile reinforcement and crack slip , as a function of the opening width and concrete deformations in relation to the cosine of the angle . The experimental " nagel " forces and crack slip dependences for the connection between and in the form of an exponent for the reinforcement deformations and spacing are determined. The forces have been calculated for two to three cross-sections (single composite strips) of reinforced concrete structures. On the bases of accepted hypothesis, a new effect of reinforced concrete and a joint modulus in a strip of composite single local shear zone for the difference of mean relative linear and angular deformations of mutual displacements of concrete (or reinforcement) are developed. The hypothesis allows one to reduce the order of the system of differential equations of Rzhanitsyn and to obtain in each joint the total angular deformations of concrete and the "nagel" effect of reinforcement. The curvature of the composite bars has a relationship from the total bending moment of the bars to the sum of the rigidities. The stiffness physical characteristics of the matrix from the compressed concrete area and the working reinforcement are obtained in a system of equations of equilibrium and deformation, as well as physical equations.

Calculation of the formation of normal cracks in a reinforced concrete element based on the deformation theory of plasticity of concrete by G.A. Geniev

“…To assess the degree of reliability of the obtained dependences, a numerical comparison was made of the results of calculating the fracture toughness moment calculated by the proposed method with the experimental data of Vl.I. Kolchunov, Al-Hashimi Omar [34], obtained using modern tools, which allowed a more detailed and accurate study of the process of crack formation in reinforced concrete structures. The results of a comparison of experimental data on the moment of crack formation, calculation data obtained by formula (23), and according to the method of SP 63.13330.2018 for beams with a section of 100×250 mm, with a total length of 1200 mm, supported on two supports and loaded with concentrated loads, from ordinary and lightweight concrete are presented in As follows from the table, the calculated value of the moment of crack formation according to SP 63.13330.2018 turned out to be significantly underestimated compared to the experimental values by an average of 30% for beam structures made of lightweight autoclaved cellular concrete and by 22.5% for beams made of heavy concrete.…”

The digital twin use for modeling the multi‐storey building response to seismic impacts

“…Based on the results of the analysis of both the possibilities of the deformation method, which is recommended by the state building regulations, and the Ukraine standard 40,41 for determining the bearing capacity of reinforced concrete rod and plate structures under bending and eccentric compression, and the picture of the crack formation in rod and flat wall structures taking into account the earthquake cyclic effects, in, 42 a methodology for the structure stiffness calculation taking into account the presence of cracks and concrete and reinforcement nonlinear operation. The regulations of Ukraine 37 recommend using the methodology for designing new buildings and facilities structures and assessing the seismic resistance of structures operated in earthquake‐prone areas.…”