Experience in operating PVC windows in the climatic conditions of the Russian Federation shows that they are subject to significant temperature deformation. Temperature deformations of PVC windows lead to a decrease in their operational and technical characteristics. Nevertheless, at present the calculation of these structures for the action of temperature loads is not performed. This is due, among other things, to the fact that the methods for calculating the plastic deformation of PVC windows under the action of temperature loads have not yet been developed. The development of this methodology is the purpose of the present research. It was proposed to divide a window construction into profile combinations and to consider the profile combination as a single calculation element. By introducing a number of simplifications, a calculation scheme of profile combination was created. A universal form of a system of differential equations describing deformation of a combination of profiles was obtained. A general form solution for this system of equations has been obtained which takes into account temperature bending of window profile elements, impact of IGU rigidity, conditions of profile fixing, point forces and moments, which enables to calculate the strain-stress state o f any structure which can be represented as a set of combination of profiles. A condition limiting temperature deformations of a window structure has been proposed. It consists in ensuring the window seal deformations not exceeding its operating range, which can be verified using the described calculation methodology.

The issues of modern construction with the use of precast reinforced concrete slabs as part of composite steel and concrete structures are considered. The rationale for the chosen research topic is given. The description and features of experimental models of the studied structures, materials and their characteristics are presented. The features of the support and loading of the models are given. The analysis of the results of testing prisms for shear and models of composite steel and concrete beams and full-sized ofcomposite steel and concrete slabs for bending is carried out. The types and nature of the destruction of models are presented, a table of destructive loads is formed. Graphs of displacements and stresses in structural elements are given. The evaluation of the existing calculation methods, their comparison with the experimental results is given. An assessment of the effect of partial concreting of steel I-beams as part of prefabricated composite steel and concrete structure and its effect on the loadbearing capacity is given.

Basic provisions are presented of scientific and methodological substantiation of corrosion protectability of steel structures and installations. Priorities have been analyzed of improving existing codes, taking into account scientific achievements and international standards. Tasks have been formulated for increasing competitiveness and resource saving through the use of effective measures of corrosion protection. The study is aimed at parameterization of a mechanism of technical regulation of quality, reliability and safety, approval and application of materials and technologies, procedures, services in the field of corrosion protection at the request of a digital consumer. A process-oriented methodology is proposed aimed at a continuous improvement of development cycles and models of the rational choice of systems of corrosion protection of structures. With that, corrosion protection of structural steel is defined by the level of reliability and required parameters of technical and economic protection. The management structure is defined by the provisions of organization standard in accordance with ISO 12944, SP 28.1330.2017 with regard to corrosion protection of structural steel.
The levels have been analyzed of reliability of structures and their protective coatings, with account for the procedures for assessing compliance of quality, monitoring and risk diagnostics based on the limit states method. Parameter compliance is affirmed based on five DMAIC principles related to determination, measurement, analysis, improvement and monitoring technical condition of structures. Examples are presented of statistical estimation of representative samples of corrosion impacts, characteristic values of corrosion resistance and durability of steel structures and their protective coatings. Proposed are methods for functional and time redundancy of corrosion protection assurance. Load testswere carried outof models of steel structures with corrosion damage.
The obtained results reveal uncertainty of parameters of corrosion state and allow assessing structural steel survivability with account for acceptable risk. Suggestions for parametric design are recommended for digital transformation of the system of technical and economic regulators of corrosion protectability.

The method of calculating the load-bearing capacity of centrally compressed tubular concrete columns of square section is considered. The technique is based on the use of a nonlinear deformation model of reinforced concrete. Accepted deformation diagrams of concrete core and steel pipe take into account their complex stress state. The proposed method takes into account the variable stiffness of different sections in height of the compressed rod when assessing the effect of its flexibility. The maximum load corresponding to the loss of strength or stability of the element is determined by the same method using the same formulas. As a result, there is no need for a separate formula for calculating the critical force. A comparison of theoretical and experimental data indicates the acceptability of the proposed calculation methodology for project practice.

The article presents the results of theoretical studies of reinforced concrete beams, taking into account the limitation of horizontal displacement on supports under short-term dynamic loading. In studies, the deformation of the structure is considered in the conditionally elastic and plastic stages. It has been established that the presence of thrust leads to a significant increase in strength and a decrease in the deformability of structures, both in the conditionally elastic and plastic stages. The paper reflects the results of a numerical calculation of reinforced concrete beam structures with thrust under short-term dynamic loading based on the obtained analytical dependencies. The effect of the thrust reaction, namely the rigidity of the support contour, on the dynamic coefficient of reinforced concrete structures is considered in comparison with structures without expansion. The results of numerical studies indicate a positive effect of the expansion reaction in dynamically loaded structures at all stages of their dynamic deformation.

Despite the widespread use of tapered beams, the features of their stress-strain state remain poorly understood, including in regions near curvatures of the faces.A lot of experimental studies have shown that in tapered beams, shear cracks occurs not only in the support zone, but also in the middle of the span directly at the apex, even without shear force.
Based on the full-scale tests of tapered beams and finite element analyses, diagrams of shear and transverse stresses are constructed. The data obtained revealed differences in the stress distribution in tapered and linear beams. The features of the stress-strain state of the tapered beams are associated with the occurrence of shear stresses from the action of the bending moment and longitudinal force due to the variable depth of the section of the element, as well as with the formation of local stress fields in areas near the curvatures of the faces.
The proposed analytical dependences allow us to calculate shear and transverse stresses in the apex zone of tapered beams and determine the moment of occurrence of shear cracks in the specified zone.

One of the main advantages of self-stressed concrete is its ability to compensate for one of the main disadvantages inherent in mineral binders – shrinkage strains. However, approaches to predicting the properties of self-stressed concrete are not universal, since they are based mainly on phenomenological approaches and empirical dependencies. The main approaches to predicting strains and stresses arising in expansive concrete are energy- and deformation approaches. A number of researchers confirm the effectiveness of applying the deformation approach to determine intrinsic strains and stresses. Modification of the model for determining its own stresses and strains made it possible to move from the case of uniaxial bar reinforcement to two- and three-axis-limited elements. Based on the provisions of the deformation approach, a deformation model was proposed to determine the intrinsic strains and stresses of self-stressed fiber-reinforced concrete. The main prerequisites and assumptions of the proposed model are formulated. A block diagram of the algorithm of the iterative procedure is given, which makes it possible to calculate the intrinsic strains and stresses of self-stressed fiber-reinforced concrete. Parametric studies of self-strains and stresses of self-stressed fiberreinforced concrete at the stage of expansion were carried out. The normalized dependences of the bounded strains on the varied parameters are presented. The area of effective use of steel fibers to achieve "binding" effect of free expansion in self-stressed concrete of different energy-activity has been determined. Influence of change of introduced fiber amount on development of bound strains of selfstressed concrete at different time intervals has been determined. The obtained results can be used in design, educational and research institutions.

With the help of probabilistic modeling, the issues related to the assessment of the robustness of structural systems made of prefabricated and monolithic reinforced concrete in an accidental design situation are considered.
The paper considers the concept of analyzing the reliability of structural systems and differentiating risks in accidental design situations. The existing probabilistic models of the basic variables included in the functions of loads and resistances are analyzed. Statistical parameters of the uncertainty of the resistance model are obtained and integrated in the form of a basic variable with probability modeling.
Probabilistic modeling of structural systems made of precast and monolithic reinforced concrete, designed according to the current standards of the Republic of Belarus, was carried out using the Monte Carlo method. The functions of the limiting state of the structural system in an accidental design situation with the sudden removal of the central column of the first floor are determined. As a result, values of failure probabilities and corresponding reliability indices were obtained for the considered constructive systems.

The article focuses on the currently relevant problem of assessing the safety of steel frame systems on a deformable soil base under accidental impacts. The article considers a case when impact actions can be random, i.e., such parameters as application point, direction and intensity of impact are not determined preliminarily. It is supposed that for the existing design solution the occurrence of such impacts should not lead to progressive collapse, and the structure as a whole should have the property of robustness. In order to estimate this property, it is suggested to carry out a number of calculations for the stress-strain state under the most dangerous random loads and then to carry out a verification analysis in the dynamic statement. For the steel frame, a search problem is solved according to the criterion of minimization of integral safety margin of structural elements. The calculations account for the possibility to prevent the frame buckling. The quasi-static analysis is performed on the basis of the models of the deformation theory of plasticity, and the dynamic analysis is done with regard to the associated law of steel yielding. The proposed procedures allow designing steel frame structures which are resistant to random accidental loads. A shock load is represented in the form of a force impulse which is statically equivalent to the dynamic effect of an inelastic impact of a rigid body on a structural system. An example of design and performance evaluation of a steel frame structure of a two-story building is considered.

In modern large cities with the status or signs of the historical, there are global transformations in the architectural and planning structure, which are both positive and negative in relation to the functional organization of the living environment. The modern problems of the historical urban center, which are the cause or consequence of reconstructive interventions, are due to both the specifics of its functional and planning organization and the current socio-economic demand. Despite this, the technical possibilities of modernizing the quantitative parameters of the urban environment of the historical center are quite specific: historical buildings, expressed in low-rise and medium-rise buildings, are subject to preservation, and incorrectly selected methods and techniques for implementing this process currently lead not only to problems of visual and identification perception of the historical and cultural urban environment, but also to functional, to which this article is devoted.
The research methods are determined by the principles of the demoecological approach, according to which the living environment is a complex self-sufficient system.
The research is based on a systematic approach: the principles of functional transformation of the residential environment in the architectural and planning structure of the modern historical city center are revealed.The revealed typology of functionally indeterminate structural planning elements of the residential environment, which are currently sites for correct functional modernization, is analyzed by a systematic approach, as a result of which the term "functional regulation" and "functional integration" was defined.

On construction sites, many human functions are performed by construction machines and mechanisms, manual labor is minimized. Robotic complexes are gradually being introduced, which over the course of several decades can completely exclude the participation of a worker in many processes at the level of the performer. Approaches to the design and management of the implementation of investment and construction projects are changing - the number of companies that introduce high-tech digital solutions into their activities, requiring personnel capable of effectively performing work in a digital information environment at each stage of the building's life cycle, is increasing. Within the framework of this study, the issue of creating and implementing a digital information model of an object at the construction stage is considered. The structure of the model is given and its influence on the organizational and technological design within the framework of the construction project is described. The factors constraining the introduction of information modeling technologies at the stages of construction of a capital construction object are indicated.

The current state and main problems of the construction complex of the Donetsk People's Republic caused by the process of integration into the economic complex of the Russian Federation at the present stage are considered. The research materials are based on the analysis of the activities of the construction organizations of the republic and the results of the scientific and design activities of the FSBEI HE "DONNASA", which is the basic organization of the Ministry of Construction of the DPR in matters of scientific and technical policy. Information is provided on the main conceptual and design developments that determine the activities of the construction complex in the near future. Recommendations aimed at overcoming the crisis phenomena in the construction complex are formulated.