The results of numerical modeling of wooden beams strengthened of composite materials based on carbon fiber are considered. Modeling of beams strengthened of composite material was carried out in the ANSYS software using deformation diagrams. The reliability of the modeling methodology was assessed by comparing the results of a numerical study with the results of a physical experiment obtained during testing of models of wooden beams strengthened of composite materials based on carbon fiber.
Keywords: carbon fiber, carbon composite materials, strengthening of wooden structures, external reinforcement of wooden beams
The article raises the problems of preserving historical architectural and natural complexes on the example of the Peter and Paul Park in Yaroslavl. In the Introduction to the article, attention is drawn to the importance of the problem of preserving historical monuments of architecture or art not only in the capital cities, but also on the periphery. The following are the main methods used in the work to assess the state of the architectural and park ensemble, to identify its characteristic architectural and landscape features and to develop a theoretical conservation model. In the main part of the article, the historical stages of the formation of the architectural and park ensemble of the Peter and Paul Park, their influence on the final appearance of the ensemble are considered; a comparative analysis with similar architectural and park ensembles is given, common characteristic features are identified and the principles of the formation of the Peter and Paul Park are established. As a result of the conducted research, a model of preservation of the Petropavlovsk architectural and park ensemble of Yaroslavl is proposed, presented in the form of a master plan of the park territory, which contains proposals for the reorganization of the territory, pedestrian park network and restoration of historically significant structures. In the final part of the article, the main conclusions based on the results of the study are formulated.
Keywords: architectural and park ensemble, Peter and Paul Park, Yaroslavl Big Manufactory, regular layout, theoretical model of conservation
High-rise buildings with CLT (cross-laminated timber) load bearing structures are being more actively developed in many countries. CLT-panels are lightweight, ecological and easy to assemble. In the article types of strengthening of three-layers and five-layers CLT-panels with carbon, basalt and flax fiber reinforced polymers (FRP) are considered. They can be used for panels under exploitation to reduce influence of defects and increase load bearing capacity and stiffness or in the production stage to reduce thickness and weigth of constructions. Known works of international authors are analyzed. Bending behaviour of externally reinforced CLT-panels is described. Areas that deserve further investigation are determined. They include investigation of different composite materials and wood types used for CLT-panels' production.
Keywords: CLT, composite, cross-laminated timber, external strengthening, FRP, high-rise building, lamella, reinforcement, timber structure, wood
The Russian Federation is a multi-religious state, which has recently seen an increase in the construction of various religious buildings. At the same time, the bulk of the churches being built are small buildings, located, as a rule, in villages and small towns and designed for simultaneous visits by up to 120-150 parishioners. Various materials are used for their construction, including wood. Usually these are log or block buildings, but it is also possible to use other wooden housing construction systems, including light frame ones. The theoretically possible remoteness of towns and villages from large district and regional centers, the impossibility of delivering large-sized beams and logs, the lack of their own production base and other factors lead to the need to use ordinary boards in wooden frame structures. As an example, we consider the construction of the Church of the Transfiguration of the Lord in one of the farms in the Rostov region, the load-bearing structures of which are made using light-frame house-building technology. The presence of open space in the central part of the Temple and the placement of an octagon-shaped superstructure above it required the use of a supporting structure made of steel I-beams. Thus, the structure of the Temple frame is a metal-wood system. The article shows that the combined use of steel and wood in light-frame buildings ensures a rational organization of the space of religious buildings.
Keywords: religious building, temple, belfry, octagon, narthex, altar, wood, light frame building, beam, I-beam, supporting structure
The influence of blast furnace ground granulated slag on the kinetics of strength gain of concrete prepared with a composite binder was revealed. The composite binder contained Portland cement in amounts of 70, 60 and 50%, and the rest was ground granulated slag. It has been established that at the early stage of strength development, concretes made with a composite binder have a strength lower than concrete prepared with Portland cement by 10-24%. However, at the age of 28 days, the strength of concrete using a composite binder corresponds to the strength of concrete using Portland cement. Using polycorboxylate hyperplasticizers, it was possible to obtain concrete with a W/C ratio of 0.25-0.35, which made it possible to obtain high early strength exceeding control compositions by 10-20%.
Keywords: portland cement, grn slag, grinding, composite binder, kinetics of strength gain, hyperplasticizer, kinetics of strength gain
The world's reserves of renewable energy sources are steadily declining, but the comfort of life in modern society should remain at the same level. The modern solution of the problems of thermal protection of facade systems of buildings is associated with the analysis of the specific heat capacity of the materials included in their composition. The use of new energy-efficient materials is becoming especially relevant. Such materials include vacuum thermal insulation panels, which significantly reduce heat loss in comparison with traditional thermal insulation.
Keywords: energy efficiency of buildings, thermal protection of facade systems, thermal insulation, vacuum thermal insulation panels, construction production
The article presents the results of a survey of two industrial buildings, conclusions about their emergency technical condition and the inexpediency of restoration. Modern methods of demolition and dismantling of buildings in the cramped conditions of the existing urban development are analyzed. The main technologies of recycling dismantling and disposal of construction waste generated during the dismantling of buildings are considered: "smart demolition" and the technology of piecemeal disassembly of buildings with the reuse of materials, products and structures. Comparing the two methods of recycling dismantling for application to the objects under consideration, it is concluded that the first method of "smart demolition" implies the destruction of all building structures, while the second is more rational in terms of resource conservation and economic efficiency by reuse of serviceable structures. The technology of piecemeal disassembly of buildings with the reuse of structures requires the development of regulatory, organizational and marketing measures.
Keywords: building inspection, demolition, dismantling, dismantling methods, smart demolition, recycling dismantling, reuse of structures
Elimination of the consequences of emergencies during rescue operations will be successful with the use of reliable modular lifting equipment. The proposed concept of the mobile equipment system contributes to the use of layer-by-layer dismantling of the rubble of destroyed multi-storey buildings and structures. The main structural elements of the system of mobile lifting equipment are presented.
Keywords: earthquakes and disasters, mobile equipment, lifting device, time minimization, modular device
The article gives a description of the developed design of a sample of the connection of wooden elements, which is devoid of the shortcomings of existing technical solutions that allow simulating the actual operation of real wooden structures. The design makes it possible to increase the reliability of the test results, simplifies the test procedure and the test results processing process. The developed design of the sample fully reflects the actual work of the real joints of the beam cage of a wooden building, causes a stress-strain state in the sample, to a large extent similar to the stress-strain state of a real joint due to the correct application of the basic provisions of the similarity theory to connect the model with the full-scale construction of a wooden buildings, schemes for applying the load to the sample and methods for conducting experiments.
Keywords: wooden structures, timber, joining of wooden elements, testing of a sample of connecting wooden elements, wooden beam, main beam, secondary beam, metal plates, screws, reliability improvement
The paper considers the problem of the arrangement of the abutments of newly erected driveways and roads of agricultural production enterprises to existing roads and driveways. When connecting the "pies" of the roadways of the projected driveways with the existing landscaping, it is necessary to solve the problem of preventing cracking in the coating at the places of the thickness difference of the structural layers. In the article, this problem is solved both from the technical side, by ensuring the joint work of the new and existing road structure, and from the normative one by assigning the projected passage to the IVB category road, in accordance with SP 37.13330.2012, which allows the construction of a road with curbs without curbs and, as a consequence, without storm sewers and sewage treatment plants.
Keywords: road network, cadastral boundaries, the design of the widening of the passage, the technical solution of the junction of roads, transverse profile
Economic development directly depends on the creation of a network of roads of the highest category. Major road construction requires large capital investments and less funds are allocated for the operation of existing roads and infrastructure. Instead of replacing bridge structures, it is necessary to use their reconstruction. The article discusses the problem of reconstruction of bridge structures, namely the restoration of carrying capacity, which has decreased during many years of operation. The relevance of the study, its goals and objectives are noted. A classification of reinforcement structures according to various criteria is proposed. The types of bridge reinforcements often used in practice, their advantages and disadvantages, are analyzed. The presented material is illustrated with photographs of objects. Successful reconstruction directly depends on the qualifications of designers and contractors, since with insufficient reinforcement, the span continues to work and is overloaded and gradually collapses. A modern method of reinforcement based on the use of carbon composite is presented. Significant disadvantages of this method for strengthening bridges and its modification using a tensioning device to secure and tension the carbon lamellas have been noted. The use of a tensioning device allows the superstructure to be partially unloaded from permanent and temporary loads. The main conclusions are presented.
Keywords: bridge, strengthening, reconstruction, truss, carbon composite, lamella, load-carrying capacity, load-bearing capacity, tension
The object of research is C-shaped elements made of thin-walled cold-formed profiles. The subject of the study is the stability of C-shaped rod elements from thin-walled cold-formed profiles. Research goal: development of the calculation process by the finite element method and determination of coefficients of loss of the overall stability of thin-walled cold-formed rods. Method. A numerical-analytical research method is used to reduce the time and volume of settlement operations. The buckling coefficients are determined by finite element analysis of the buckling of the overall stability of cold-formed elements of light steel thin-walled structures using the software package. Result. This analysis results in a table of total weight coefficients for cold-formed thin-walled rods, which can be presented as a table for calculations on medical indicators—a comparative analysis of the inverse numerical-analytical calculation method with the finite element method using the computer program.
Keywords: stability, finite element method, thin-walled cold-formed profiles, steel, coefficients, software package, construction
The paper describes a model of behavior of the connection of wooden structures with glued rods when exposed to negative temperatures. The results of determining the resistance of wood to punching of a glued rod of reinforced joints of wooden structures at temperatures of -30°C, -70°C and +22°C are given. The characteristic features of the destruction of the reinforcing bar and the connection as a whole are revealed.
Keywords: wood, glued rods, extreme temperature and humidity conditions, indentation strength of adhesive bonding of metal rods
This article discusses the process of collecting initial data for the cadastral assessment of cultural heritage objects. It has been revealed that cultural heritage objects have a number of features among other real estate objects, so special attention should be paid to the methodology for assessing such objects. The purpose of the study is to analyze and identify problematic issues in collecting initial data on cultural heritage objects during the state cadastral assessment. The results of the study showed a number of problematic issues related to the type of cultural heritage object, its binding to the cadastral number and the possibility of interpreting the information received to bring it to automatic data processing.
Keywords: state cadastral valuation, cultural heritage object, collection of initial data, interdepartmental interaction, status of cultural heritage object
The paper considers the opportunities and obstacles to the integration of renewable energy sources (RES) in megacities on the example of Moscow. The paper analyzes the applied RES-based generation technologies, taking into account their applicability in large cities. Special attention was paid to the conversion of unused historical dams into small hydroelectric power plants (SHPP) as an integration of RES in megacities. Based on the results of the technical and economic analysis, it was found that the conversion of an unused dam on the Yauza River into a SHPP is justified.
Keywords: small hydropower, unused dam, megacity, renewable energy integration
One of the actual problems in the field of analysing loads and impacts on bearing structures is their identification. It means the point of application, the type of action and its intensity in cases where there is an impact result, but the parameters that caused this result are not determined. For example, it is an accident action, as a result of which the structure is deformed and collapsed. The solution of such problems arises when analysing accidents on load-bearing structures in construction, as well as when monitoring the deformed state of structures in time. The paper proposes to use the principles of neural network modelling to solve the problem of identifying the impact in the form of a concentrated force on the example of beam systems. The values of linear and angular nodal displacements at some action are considered as input data to neurons. As an example, the linearly deformable beam of constant stiffness is considered, the material of which is a continuous isotropic medium.
Keywords: neural network, deflections, load-bearing structure, displacement, deformation, identification
he article considers a plane problem of calculating the interaction of a culvert of different outlines with a soil embarckment, taking into account the constructive nonlinearity. Due to the impossibility of the soil to work in tension, the interaction of the pipe and soil is assumed to be uniulateral. In the problem, the outline of the pipe is changed, other parameters being equal. As the results of the calculation, the area of contact / separation and adhesion / slippage of the pipe with the soil is considered. Based on the results of calculations, recommendations are given for choosing the outline of culverts.
Keywords: constructive nonlinearity, frictional contact, unilateral constraints, linear complementarity problem, numerical models, finite element method
On the example of the beams, the dynamics of systems with unilateral constraints are considered. The algorithm for calculating such systems as a combination of the step method of Newmark and the Lemke algorithm that determines the work scheme of the beam in each time step is proposed. Model tasks are considered with a harmonic exciting force, suddenly applied force, impulse exposure. The numerical convergence of the solution was investigated during the thickening of the temporary grid. It is shown that the accuracy of the solution significantly depends on the determination of the moment of changing the working schemes, since the error of the solution increases with an increase in the events “inclusion/off” of unilateral constraints.
Keywords: constructive nonlinearity, unilateral constraints, linear complementary problem, Lemke's algorithm, structural dynamics, Newmark's method
The article disrible a lot of novel patents in Civil Engineering, more of them from China
Keywords: patent's description, civil Engineering
The article discusses the possibility of using the ANSYS WORKBENCH software package to calculate the uneven settlement of building foundations. The heterogeneity of the physical and mechanical properties of the soil, the difference in the thickness of the bearing layer and other factors lead to uneven development of settlement. This causes the appearance of cracks in the supporting structures, and in the worst case, the destruction of part of the building or the building as a whole. Methods for calculating settlements are very complex, but using the capabilities of modern computers and computer simulation programs makes it possible to obtain a simple and accurate solution to such problems. To evaluate the deformations of the foundation on heterogeneous soils the ANSYS software package was be used. The proposed method can be used to quantify the uneven settlement of the foundations of real buildings and structures.
Keywords: ANSYS WORKBENCH, foundation, uneven settlement, skew, computer modeling, deformation, finite element method
Steel roof trusses are the main type of load-bearing structures used in the roofing of industrial buildings. Among them, trusses of the “Molodechno” type have become widespread, in which closed bent-welded profiles of square and rectangular cross sections are used as rods. The use of this type of rolled product makes it possible to create structures without gussets and connecting strips, with a maximum degree of process automation, which significantly reduces labor intensity and reduces the cost of their production. Another feature of the coatings under consideration is their non-running solution. The trusses are located in 4m increments, supported by rafter structures. However, in such a situation, the loads on the truss and the forces in the elements are small, and therefore, and also taking into account the limited range of bent-welded profiles, understressing of the truss elements and excessive consumption of metal are likely. Three variants of coatings with different pitches of trusses were considered, and the metal consumption per square meter of coating was determined. It has been proven that with increasing pitch of trusses, the metal consumption of coatings decreases.
Keywords: "Molodechno", rafter truss, sub-rafter truss, continuous purlin, lattice purlin, truss pitch, metal consumption
Studies of a circular cylindrical mesh shell with additional rods and increased rigidity of the supporting ribs were carried out. As part of the search for the optimal design, the criterion of rational material consumption was used. According to the results of the conducted studies, the regularities of the distribution of force factors and deformation parameters were revealed. An assessment of the degree of activity of the work and vulnerability to deformations was carried out. Dangerous areas of surfaces are analyzed, mosaics of forces and displacements are obtained. The contribution of reinforcing elements is determined and the influence of the stiffness of the supporting ribs is revealed. A significant unloading of the spatial structure was achieved and a high level of impact resistance was recorded. A significant decrease in calculated indicators was obtained.
Keywords: cylindrical mesh shell, reinforcement with rods, stiffness of support ribs, optimization, forces, displacements, material consumption
A review of studies of photovoltaic chromatic devices for regulating the transparency of glass and simultaneous generation of electrical energy through an internal photoelectric effect is given. Devices based on thin-film heterostructures with kesterite as a photocell are considered in detail. Kesterite is an absorbing material consisting of copper, tin, zinc, sulfur and selenium, a new promising material for creating "smart" glazing with adjustable transparency. The energy characteristics of coatings based on kesterite are compared with coatings of other types. The prospects of kesterite as a basis for creating effective autonomous photovoltaic windows of adjustable transparency are shown.
Keywords: photoelectric effect, transparency, glass, kesterite, perovskite, silicon, window, energy efficiency, electrochromic effect
The safety of hazardous production facilities is directly related to the reliable operation of pipeline systems, as a failure occurring in the elements of such systems can lead to serious consequences for production facilities and the environment. Since the greatest number of failures is associated with faults caused by corrosion, to increase reliability it is necessary to increase the corrosion resistance of metal of pipeline elements. The article gives an overview of materials for manufacturing parts, the influence of different climatic conditions on the mechanical properties of steels. The developed rotary gate designed for automatic prevention of reverse flow of working medium is also presented. To confirm the serviceability of the design, strength calculation of the structure was carried out, where its stress-strain state under the given loading conditions is considered. As a result, the values of maximum equivalent stresses, maximum deformations and displacements were obtained, which are lower than the maximum permissible ones.
Keywords: pipeline system, pipeline, shut-off valves, swing back gate, mathematical modelling, finite element method
A new building structure is proposed - a welded steel I-beam with a prestressed perforated wall. The prestress in the beam is created by stretching the web and subsequent welding with chords. Before prestressing, holes are cut in the wall. Using the LIRA-SAPR software package, a model is proposed that can be used to study the operation of a prestressed perforated beam (PNPB) structure. The influence of various forms of voids in the wall on the change in the stress-strain state of steel I-beams prestressed by the wall drawing is studied. A preliminary assessment was made of the favorable effect of prestressing in a conventional perforated beam on the stress-strain state of beams with different forms of perforations in the web.
Keywords: steel structures, prestressing, numerical experiment, normal and shear stresses, bearing capacity