Tkachuk I. Strength of reinforce-concrete columns under force and high temperature influences

The content of the thesis. In the introduction it substantiates the relevance of the topic, formulates the purpose and tasks of the research, scientific novelty and practical value of the work, and also the general characteristic is presented. Chapter 1 is given over to analyzing modern methods for calculation and design of load-bearing reinforce-concrete members of buildings and structures working in compression under various influences. The existing proposals for taking into account the nonlinear properties of reinforced concrete are analyzed. It is noted that a feature of the calculation methods proposed by various authors is the use of various assumptions on concrete strength. Various material behaviour models are considered. In chapter 2 the methodological approach of the estimation of the technical state of constructions of frameless buildings with reinforce-concrete framework.The primary purpose of realization of the works of the building construction technical state estimation is the receipt of the controlled (qualificatory) parameters of the technical state. The estimation of the technical state of building constructions is conducted by comparison of the controlled parameters with corresponding project parameters, and also on results of checking calculations. The controlled parameters are determined during realization of visual and instrumental inspections. In the chapter the features of determination of the technical state of constructions after fire effect are also brought. Chapter 3 presents the results of experimental studies concerning changes in the strength characteristics of reinforcement under high-temperature influences and fire resistance of columns. To obtain experimental evidence indicating the nature of deformation and failure of steel reinforcement when exposed to high temperatures, a study of samples made of reinforcing steel of various classes was carried out in accordance with the requirements of current regulatory documents. Chapter 4 contains proposals for determining the fire resistance of reinforced concrete columns and other structures in compression. The procedure has been developed for calculating the fire resistance of reinforced concrete columns using a thermo-technical calculation, which allows for the accepted assumptions to determine the temperature distribution in the cross section of the column when heated. The urgency of the problem concerning calculation of load-bearing reinforceconcrete structures in compression, taking into account the strength properties of reinforced concrete under various influences, is noted for Ukraine.