The objectives of the study were to improve the operational characteristics of buildings with a bearing reinforced concrete framework located in seismic areas of the Russian Federation. The article presents the results of analysis of previous studies of stress-strain state of the framework elements of a multi-storey building under seismic impacts. It has been established that despite a more optimal solution of load-bearing systems of buildings in the form of reinforced concrete frames in seismic areas as a result of periodic actions of background earthquakes, inevitable accumulation of temporary fatigue and damage to structures during operation there is a significant reduction of dynamic resistance of the building as a whole. It is noted, that throughout all term of life of an object except design seismic load, the crucial role is played also by physical wear which development leads to structural modifications of properties of materials and inevitable deformation of technical characteristics of bearing structures. It has been found, that the most dangerous failures associated with the reduction of strength of columns, assemblies, the mating of bearing elements and, as a result, the loss of their stability, leading to the progressive destruction of the building as a whole. Three groups of possible methods of strengthening and increasing seismic resistance of buildings and structures are considered.

The estimate of failure probability on the inclined section from the action of transverse forces, as well as the total probability of the limit States of reinforced concrete beams with probabilistic strength parameters lying on an elastic Foundation model V.Z. Vlasov-P.L. Pasternak, possessing stochastic properties. Probabilistic characteristics of the transverse force and its distribution density are constructed for a Foundation beam resting on an elastic base with two random characteristics, loaded with a quasi-stationary random load, taking into account the probabilistic nature of the strength properties of concrete and reinforcement. It is shown that if the spectral densities of the bed and load coefficients are fractional rational functions, the deflection correlation functions and, accordingly, the deflection variance are calculated using the residue theory.

In SP 63.13330 the general calculation case for the diagram method is oblique off-center compression, which takes into account only three components of internal force factors in the cross section: the longitudinal force-Nz - and two bending moments relative to the corresponding axes - Mx and My. The other three components-the QX and Qy transfer forces and the M _Z torque - are left out of consideration. In addition, for this case, the search in the available literature, including the founders of the diagram method, for the output of calculation formulas was not successful - in all sources they are given in ready-made form without evidence. This article is intended to try to fill in these gaps. For this purpose, based on the expressions for rod displacements that are generally accepted in mechanics, in particular on the Mora integral of displacements, the resolving expressions of the diagram method are obtained in the most general form.

The architecture of modern structures requires the use of structural systems in a wide range of both geometric and topological forms. Spatial steel structures are one of the most varied, complex and demanded types of structural forms of coatings for buildings and construction structures. The method of constructing spatial lattice structures of a complex geometric shape considered in the article is based on automated methods of computer modeling of the shell surface and the subsequent development of a separate spatial cell of a lattice of a certain type - a "family". The structural cell of the lattice is the basis for the topological structure of the building system, which is created using special software. The result of this development is a digital model of the megastructure of the entire spatial structure. Subsequent export of the constructed geometry to computational software systems allows one to estimate the stress-strain state of the system and select the cross sections of all its elements. The methodology developed in the article makes it possible to quickly and accurately design spatial structural structures of coatings of an arbitrary geometric shape. The speed and accuracy of modeling and calculation of shell lattice structures is achieved by optimizing the sequence of application of modern programs, using special modeling techniques.

The paper considers issues of construction of test methods and testing of basalt rods proposed by the authors. A basalt rod is a bundle of twisted basalt roving threads packed in an epoxy laminate. Due to the lack of analogues, a methodology for testing reinforcing rods using existing testing machines is being developed. The analysis of Russian and foreign normative documents, which could form the basis of the test methodology, was carried out. A general lack of testing equipment is noted, leading to the destruction of the basalt twisted yarn in the grippers prior to testing. A test procedure is proposed and the results of experiments are presented, which make it possible to assess the bearing capacity of a reinforced specimen. Conclusions and recommendations for testing structures reinforced with basalt rods - laminates are presented.

In the current situation of development of the underground space of cities, the main task is to ensure safety and maintain the normal operation of both the building under construction and existing buildings and structures located in the zone of influence of new construction. The article considers the design of the dividing screen in the form of a continuous vertical geotechnical solid, made of jet-grouting elements. The analysis of existing analytical and numerical methods of static calculation of such structures is carried out. A computational model of the screen structure in the form of a plate lying freely on a two-parameter elastic base and being under the influence of a distributed arbitrary load is proposed. The calculated simulation of the dividing screen operation at the stage of building operation is performed. The main factors influencing the distribution of internal forces in the screen design are determined.

The results of experimental and theoretical researches of crack resistance, development and growth of cracks of a fragment of a reinforced concrete multi-storey frame of a monolithic building with prestressed beams for a special emergency impact caused by a sudden removal of one of the load-bearing elements are presented. Removal of the middle column of the frame was considered as an emergency impact. Analysis of the pattern cracking in the frames with a prestressed beam before and after a special impact is carried out against the pattern cracking in an unstressed frame structure. Based on the increments of cracks width in the beam, the coefficient of dynamic additional loading in prestressed frame structures from a special impact was calculated. The obtained results of experimental and theoretical researches of the crack resistance of frame structures in considered influences can be used in the development of methods for protecting the frames of monolithic multi-storey buildings against progressive collapse.

On the basis of theoretical and experimental studies, the assumptions and calculation method for flexible and compressed-curved reinforced concrete structures with zone reinforcement made of steel fiber operating under static and short-term dynamic loads are formulated. In the developed method for calculating the strength of normal and inclined sections, a nonlinear deformation model is implemented, which is based on the actual deformation diagrams of materials. To confirm the main results of this method, numerical and full-scale experimental studies of reinforced concrete beam structures reinforced with conventional reinforcement and a zone steel-fiber layer were planned and carried out. Experimental studies were carried out under static and short-term dynamic loads. As a result of the conducted experiments, data were obtained that characterize the process of destruction, deformation and crack formation of steel-reinforced concrete elements under such types of loading. The efficiency of fiber reinforcement of normal and inclined sections for increasing the strength and deformation characteristics of reinforced concrete structures is revealed.

In this work, using waste from the chemical industry - aluminum-containing nanotechnogenic raw materials and a fuel and energy complex - coal enrichment based on phosphate binders, heat-resistant concrete with high physical and mechanical properties is obtained. Thanks to the use of orthophosphoric acid as a binder, it was possible to utilize 80-90% of chemical industry waste and coal preparation, which helps to reduce the anthropogenic load on the environment and humans. Studies show that as the grain size decreases, the total size of the interface is increased, the average radius of curvature of the convex sections decreases, their excess surface energy grows, and the distances between the sources and absorbers of vacancies in the system decrease. Experimental studies and rich practical experience in ceramic industries confirm the crucial role of the degree of grinding (or the use of nanoscale raw materials). Due to the action of this factor alone, it is possible in some cases to reduce the required sintering temperature by 50-100 °C or more. The use of industrial wastes in the production of building materials contributes to: a) the utilization of industrial wastes; b) environmental protection; b) the expansion of the raw material base for heat-resistant concrete based on phosphate binders.

Climate change affects cities and settlements in the Russian Federation. In addition to the increase in outdoor air temperature, its relative humidity also changes. Increasing humidity in the internal environment of buildings leads to negative phenomena, such as dampness of the room, which has a negative impact on the well-being of people and the safety of buildings 'enclosing structures. In some cases, in addition to General exchange ventilation, it is possible to regulate the humidity state of the premises by using a sorbing material as a lining for the interior surface of the premises. In NIISF RAASN, analytical and mathematical studies of the humidity state of premises in the annual operation cycle were conducted, which showed that the relative humidity in the room can be regulated by using the correct selected sorbing material.

The anthropogenic load on the planet’s natural resource potential is growing rapidly, therefore, special attention is paid to the development of less costly and low energy-intensive technologies for obtaining new building materials, the implementation of which does not require high-temperature and expensive technological processing, and will allow the use of local secondary and substandard raw materials. The development of formulations of clinker-free binders of alkaline activation based on fine powders of natural and technogenic origin will allow to obtain new effective building composites. The paper reveals issues related to the theoretical foundations of the formation of the structure and strength of cement stone based on an alkaline activator. The research results, in our opinion, undoubtedly are of practical importance for the construction industry, since the proposed recipes for clinker-free cements can replace expensive and energy-intensive Portland cement, allowing you to create strong and durable concrete and reinforced concrete structures.

The article verifies some approximating power-law and hyperbolic dependences between stresses σ and deformations ε for experimental deformation diagrams of cement concrete and polymer concrete. When analyzing the state and residual life of reinforced concrete structures, one has to solve the problem of determining the relationship between stresses and deformations in various design sections of structures. The traditional approach, based on the selection of the approximating function "σ - ε" from the numerical values of the deformation diagram obtained by testing samples (cubes, prisms, cylinders), is practically impossible. Therefore, an alternative approach is proposed based on the selection of an approximating function according to standardized indicators: ultimate strength (); modulus of elasticity (); ultimate deformation (). The numerical values of the normalized indicators can be determined at a given point by analyzing the results of indentation of the indenter into the material of structures. As approximating ones, consider the power functions that are most preferable for materials with a fractal structure. Various boundary conditions are considered for determining the constant coefficients α and β according to the system of normalized indicators. The graphs of changes in tangent modules are analyzed.

The article considers the developed model of the closed-cycle economy, which, along with economic parameters, takes into account pollution and consumption of building materials suitable for recycling. The model reflects the idea that the economic growth of a society alone cannot maintain or improve the existing quality of the environment, and for this it is necessary to increase the recycling rate. The purpose of the study is to reveal the factors influencing the increase in the level of recycling when introducing efficient and environmentally friendly systems for managing construction waste in megacities. The results of the study will affect the improvement of the quality and standards of life of the city population, the creation of favorable conditions for a safe, healthy and the prosperous life of people while ensuring the economic growth of the city. The process of the managing the growing volume of construction waste is reflected, recycling is emphasized.