This article presents a literature review of experimental studies of reinforced concrete columns under central compression. The studies reviewed include a number of experimental tests of spiral-reinforced concrete columns. Columns made of high-strength concrete with circular or rectangular cross-sections are considered and discussed in detail. It is shown that a significant increase in the strength and ductility of high-strength concrete columns can be achieved by using an adequate amount of spiral reinforcement. The volumetric content of spiral reinforcement, the spacing, and the strength of concrete affect the stress-strain state of confined concrete in high-strength reinforced concrete columns. In almost all cases, an increase in the volumetric content of spiral reinforcement leads to an increase in the strength and ductil-ity of the confined concrete core, as well as to an increase in the stresses in the spiral reinforcement when the concrete reaches its maximum strength. 

Reinforced concrete is the primary structural material for the construction of buildings and structures of various purposes. One of the key characteristics determining the safety, durability, and reliability of such structures is their load-bearing capacity. The main factor reducing the load-bearing capacity of reinforced concrete structures is corrosion, which poses the greatest threat to flexural members. This paper examines the influence of chloride-induced corrosion damage in the concrete compression zone on the load-bearing capacity of reinforced concrete flexural beams. It has been established that corrosion damage in the concrete compression zone leads to a degradation of its strength properties, which, in turn, results in a reduction of the beam's overall load-bearing capacity. Furthermore, corrosion leads to the disengagement of the compression reinforcement from carrying load, which also contributes to the reduction of the flexural member's load-bearing capacity. 

The problem of ensuring the durability of reinforced concrete structures operating in aggressive environments remains extremely relevant. Corrosion of the reinforcement caused by exposure to chlorides leads to a significant decrease in load-bearing capacity and requires expensive repairs. A promising alternative to traditional methods of reinforcement with steel elements is the use of carbon fiber-based composite materials (CFRP), which have high strength and corrosion resistance. However, their durability under long-term exposure to aggressive environments has not been sufficiently studied. The purpose of this study was to experimentally evaluate the effectiveness of reinforcing bent reinforced concrete elements with carbon fiber and the effect of a chloride-containing environment on them. The methodology included testing a series of beams with different reinforcement schemes: without reinforcement, reinforced before corrosion, and reinforced after preliminary corrosion. An electrochemical method was used to accelerate corrosion. The results confirmed that rebar corrosion reduces the bearing capacity of the blocks by 50–60 %. The CFRP enhancement allowed it to be increased by 52 %, changing the nature of the fracture from a normal to an inclined section. The key conclusion is that the external composite reinforcement effectively protects the structure, however, repeated corrosion of the reinforced element causes an increase in internal stresses and the formation of cracks in concrete due to the accumulation of corrosion products. The study highlights the need to take these factors into account to ensure the durability of reinforced structures. 

The idea of relating deformation to internal force dates back to Galileo (1638), who first examined the elongation of a bar under load, and to Hooke (1678), who formulated the fundamental law of linear elasticity. Building on this foundation, Jacob Bernoulli (1694) — one of the founders of strength-of-materials theory — was the first to pose the problem of the elastic curve, attempting to extend the laws of axial deformation to bending. However, the absence of a closed geometric relation between curvature and internal forces prevented him from completing a general theory. Euler (1744), developing Bernoulli’s ideas, introduced a variational principle based on the minimization of curvature, but employed two critical assumptions — constant horizontal projection and small rotations — which led to the classical linear Euler – Bernoulli beam theory. These ap-proximations removed axial deformation from the energy balance and introduced a hidden geometrically induced axial force not represented in the strain-energy functional. In this work, we propose the Topological Beam Theory (TBT) — the first geometrically exact model of bending formulated in the natural arc-length coordinate and employing the exact curvature definition of Huygens. The model incorporates axial deformation directly into the variational principle, introduces a topological curvature modifier 1/(1 + N/EA), and yields a closed system of equations for the rotation angle, axial force, and bending moment. Thus, the present study completes the conceptual line initiated by Galileo, Hooke, Bernoulli, and Euler: for the first time in over 330 years since Jacob Bernoulli posed the problem, we obtain a fully exact solution for the elastic curve that consistently accounts for both bending and axial deformation within a unified, energetically coherent topological model.

The results of calculating a high-rise building with a frame-braced frame made of monolithic reinforced concrete, located on a rocky base, for operational and seismic impacts according to regulatory documents from the following countries: Russia and the countries of the former USSR, the European Union, the USA, Turkey. The calculation was performed using the linear spectral method for seismic effects with acceleration at the base of 1 and 2 m/s2. The paper notes some peculiarities of the approach to the definition of seismic force. A comparison was made in terms of maximum displacements in the direction of seismic impact and forces in the elements of the bearing system of a multi-storey building: the corner, edge and middle pylons of the first floor. The results obtained indicate a similar approach to the problem of calculating a building by decomposing forms of natural oscillations of the system for seismic effects. At the same time, some regulatory documents have been identified that generate the most and least force.