The study focuses on the design of load-bearing monolithic concrete and reinforced concrete walls of low-rise buildings erected from permanent formwork ComBlock units for construction, in areas without episodic influences and analysis of their work. While developing the recommendations the main attention was paid to working out design solutions of load-bearing monolithic walls with minimal reinforcement consumption. The guidelines contain general provisions for the design and calculation of load-bearing vertical elements of a house; numerous studies of the stress-strain state of monolithic vertical load-bearing elements of low-rise buildings with different structural schemes.

New regulatory documents have been adopted and they have significant differences. Firstly, this is a new concept of calculation, a nonlinear deformation model, and secondly, new approaches to the assessment of reliability, loads and impacts, methods of construction. The calculation consists of two stages. The first begins with the determination of the concrete class at temperature of 20ºC. At the second stage, the calculation is carried out at high temperatures according to Eurocode 2 part 1-2. Comparison of the “stress - strain” diagram of concrete class at compression and temperature of 20ºC by two formulae showed their big gap. There was a need to improve the mathematical model of the ratio of stress-strain of the concrete under elevated temperatures. The method of determination of maximum strain based on energy approach has been developed in the work and allowed to formulate the adjusted dependence of the limit strain on temperature, dependence of maximum strain on temperature, values of the parameters of stress-strain diagram.

The calculation consists of two stages. The first one begins with the definition of their class, bearing capacity at temperature of 20 °C, according to EN 1992-1-1. At the second stage, the calculation at high temperatures shall be carried out in accordance with Eurocode 4 part 1-2. Comparison of the “stress-strain” diagram of concrete of class 30 under compression and temperature of 20 °C in two formulas showed their difference. That is, the designers do not have the opportunity to continue the calculation of diagrams at different heating temperatures. There was a need to improve the mathematical model of the “stress-strain” ratio of concrete high temperatures, clarification of the criteria of the bearing capacity of concrete in calculation of the fire resistance of composite structures in EN 1994-1-2:2005. In this paper, the method of determination of εcu1,θ developed has allowed, based on the energy approach, to formulate the corrected dependence of the limit deformation on temperature, dependence of the maximum deformation on temperature, and the value of the parameters of the “stress-strain” diagram. According to these data, using the formulas of the first stage, the “stress-strain” diagrams of the concrete of class 30 are calculated at the compression and heating according to EN 1992-1-2:2004.

Abstract. The efficiency analysis of the application of glass composite reinforcement in compressed concrete elements as a load-carrying component has been performed. The results of experimental studies of the deformation-strength characteristics of this reinforcement on compression and compressed concrete cylinders reinforced by this reinforcement are presented. The results of tests and mechanisms of sample destruction have been analyzed. The numerical analysis of the stress-strain state has been performed for axial compression of concrete elements with glasscomposite reinforcement. The influence of the reinforcement percentage on the stressed state of a concrete compressed element with the noted reinforcement is estimated. On the basis of the obtained results, it is established that the glass-composite reinforcement has positive effect on the strength of the compressed concrete elements. That is, when calculating the load-bearing capacity of such structures, the function of composite reinforcement on compression should not be neglected.