The thesis is devoted to the development and evolution of models for assessing the reliability and safety of the "building - base" system. Object – the processes of degradation of building structures and bases during operation. The goal is to build and develop models for assessing the reliability and safety of the «building – base» system; methods – the theory of reliability of building structures; methods of solid deformable body mechanics; methods of mathematical modeling of the stress-strain state of building structures; methods of technical diagnosis of brick structures; experimental research methods for the operation of structures; methods of mathematical statistics and probability theory; Monte-Carlo simulation method; novelty – for the first time an integrated model of failure of brick buildings operated in an unevenly deformable base was developed; for the first time, a methodology was developed for determining the probability of destruction of brick structures due to the achievement of each of the possible limiting states; for the first time, a methodology has been developed for estimating the probability of failures of the «building – base» system, including during reconstruction, when structures are strengthened, in complex engineering-geological conditions; the mechanisms of destruction of brickwork under conditions of uniaxial compression were experimentally established, the relationship between the load degrees and the technical condition category of brick beams-walls supported on a non-uniformly deformed base was obtained; experimentally obtained dependence of the average value of the strength of the masonry under compression and the modulus of deformation of the masonry, depending on the thickness of the mortar joint; a model of the life cycle of the operation of the «building – base» system; further development was obtained: statistical models of the material, loads and impacts, unevenly deformed soil foundation in the «building – base» system; phenomenological model of accumulation of damage to the brickwork; crack patterns of brick construction, as a function of the parameters of the stress state; methodologies for determining the probability of exceeding the limiting deformations of the soil foundation of the «building – base» system, approaches to the finite element modeling of the «building – base» system; results - an integrated model of failure of brick buildings operated in conditions of an unevenly deformable base was developed, which includes appropriate models of impacts on structures, materials models, bases, a phenomenological model of damage accumulation, and environmental effects; developed using the statistical Monte Carlo method of determining the probability of destruction of brick structures due to the achievement of each of the possible limit states of the first and second groups, which contains the necessary algorithms and computer programs; the methodology for determining the probability of exceeding the limiting deformation of the soil bases of the «building – base» system was developed using the statistical Monte Carlo method, and an algorithm and a computer program were created that implement the proposed calculation method; developed using the statistical Monte Carlo method, the methodology for estimating the probability of failures of the «building – base» system, which takes into account the random nature of external loads and impacts, the properties of the base and allows us to estimate the probability of destruction of a brick structure associated with exhaustion of strength from several influences; a model of the life cycle of the operation of the «building – base» system has been developed, in which the numerical reliability parameter, which serves as a quantitative integral assessment of the technical state of the system, is taken as a criterion for the technical condition of the system; it has been experimentally proved that the mechanism of destruction of brick structures of wall fragments under conditions of uniaxial compression, based on an unevenly deformed foundation, as well as brick pillars from central and off-center compression, occurs according to the separation, shearing, crushing, and destruction of the brick and mortar material with a clear determination of the stages of deformation and destruction of the brickwork; the influence of the magnitude of the effective stresses during central and eccentric compression of brick pillars on the formation of cracks and on the work of the masonry as a whole was established experimentally obtained dependence of the average value of the strength of the masonry in compression and the modulus of deformation of the masonry for different values of the thickness of the mortar joint; recommendations have been developed for the construction of reinforced damaged brick pillars using reinforced concrete cages with mesh-dispersed reinforcement; field – construction.
