Helipad on the building roof design features

The following items are considered: requirements, constructive decisions for helipads; covering plate design of the helipad located on the building roof; helipad modeling in LIRA CAD SP; calculation of a multi-storey building with a helipad on the roof, check for strength and rigidity; characteristics of the helipad on the building roof.

Modeling of joint work of steel beam constructions with reinforced concrete ribbed floor slabs

Traditional methods of calculation of beam constructions of floors and coverings of industrial buildings assume their consideration when calculating separately from the frame structures, in particular, reinforced concrete slabs, without taking into account their joint work, which leads to a significant margin of safety. Today in Ukraine there is a significant number of industrial buildings and structures that need strengthening and reconstruction. In this regard, of particular importance are studies of the actual load-bearing capacity of the frames of single-storey and multi-storey industrial buildings, and both in the reconstruction and in new construction, the results of which will significantly reduce costs and more rationally design structures. At the same time, one of the most relevant areas is the study of the joint work of metal load-bearing structures with prefabricated reinforced concrete structures of rigid disks of coatings and floors in their calculation. Moreover, in the national building codes, as well as in the educational and methodological literature, the calculation methods of taking into account the joint work of such constructions are not fully covered. The purpose of this work is to estimate the reduction of mass of the metal beam structure in its calculation in bending, taking into account the joint work with the rigid disk of the floor consist of precast concrete. As part of the study, the calculation of the floor beam according to the traditional calculation scheme - without taking into account the joint work with the floor slab, the calculation of its cross-section taking into account the joint work with floor slabs and experimental numerical study of the floor by the finite element method. Modeling of the floor fragment was performed in the software packages "SCAD Office" and "LIRA CAD 2019". Numerical research is aimed at verifying the feasibility of using the calculation methodology of DBN B.2.6-98-2009 to determine the effective width of the shelf when calculating the T-sections for prefabricated reinforced concrete slabs, which are included in the joint work with the floor beams. A comparative analysis of the obtained cross-section of the beam with the beam which was previously calculated by the traditional method of calculation in stresses in the most dangerous cross section and the total mass of the beams. According to the results of the analysis, the correctness of the application of the above normative method for determining the effective width of the shelf of T-bending reinforced concrete elements was confirmed.

Wastewater treatment of industrial enterprises from copper compounds by feritization

The article is devoted to solving an urgent problem - the development of effective methods of water purification from heavy metal ions from industrial wastewater. Today more emphasis on technologies that allow recycling of precious metals, the organization of return water supply and receipt safe disposal of sludge. Experimental studies of copper ions extraction from industrial wastewater of galvanic production by ferritization method have been carried out. The process of formation of ferromagnetic compounds of copper and iron has been studied. The results of X-ray diffraction analysis of the mineralogical composition of the samples and phase transformations that occur during aging and during the experiment are presented. The lattice constant of the α-ferite phase is calculated. X-ray diffraction analysis confirmed the presence of ferite compounds and metallic copper. In this case, in the process of "aging" of the samples, the amount of the ferrite phase and metallic copper increases. Electron microscopic analysis confirmed that in the surface layer changed due to the formation of new phases, copper-containing iron oxides, the formation of cement copper and cuprospinel simultaneously exist. The influence on the course of the ferritization process of its conditions - the concentration and ratio of copper and iron ions, temperature, pH of the medium, the consumption of oxidant - oxygen is studied. The optimal parameters of the ferritization process for wastewater treatment from copper with an initial concentration of up to 10 g / l are determined. The possibility of formation of copper ferrite without aeration at a temperature of 200 C is shown. The study of physicochemical properties of sediments formed during ferritization is performed. Studies have shown that the residual concentration of copper in the solution after the application of the proposed technology is in the range from 0.14 to 0.6 mg / l. The efficiency of copper removal is 99.98%. It is established that at the process temperature within 50… 700 C, the ratio Cu: Fe = 1: 2.7, pH = 8.8… 10.5 and aeration intensity 4… 8 l / min precipitates are formed, which consist in the vast majority of ferrites and metallic copper.

Investigation of heat loss of nodal connections of structures of energy -efficient "green" buildings

The construction industry is the main consumer of natural resources, characterized by significant consumption of non-renewable resources and the impact on environmental pollution. Up to 50% of carbon dioxide emissions are accounted for by the construction industry. In addition, the main feature of the traditional construction industry is the overuse of energy, which affects the process of global warming and climate change. Energy is consumed in the extraction of raw materials, production and transportation of materials, in the process of construction, operation, repair and liquidation of buildings. Awareness of global environmental problems has led to a rethinking of the process of design, construction, operation and disposal of buildings in the European Union, the United States, Canada and others and the emergence of the concept of sustainable development and "green" construction. In this aspect, the main criteria for designing buildings are to minimize the impact on the environment, as well as reduce energy costs, reduce waste and harmful emissions. The solution of the above problems, taking into account national specifics, can be achieved by developing typical resource- and energy-efficient, cost-effective design solutions for load-bearing and enclosing elements and their joints using environmentally friendly materials of local origin (wood and materials based on it, clay materials, straw, reeds, etc.

Technological features of metal structures strengthening by gluing of high-strength FRP-systems during reconstruction

The building heritage of Ukraine includes numerous examples of metal structures, especially used in industrial buildings and for large-span structures. The use of metal structures in construction is primarily due to their mechanical properties. They are frost-resistant and can withstand temperatures down to -65 degrees, tough, resistant, durable and reliable. They can also be used in areas with increased seismic activity. But, in certain situations metal structures need to restore or strengthen due to structural defects, wear of load-bearing elements, as well as in order to increase the bearing capacity. In some cases, strengthening with fiber-reinforced polymer composites (FRP) gives better results than traditional methods with metal strengthening. A significant part of the Ukrainian architectural and historical heritage is made up of buildings and structures using metal structures. The first designs were made of cast iron or wrought iron (machined or tinned), but they subsequently developed rapidly along with the evolution of methods for forging mineral iron. The main cultural reason for the restoration of old metal structures that guarantee structural functionality and load-bearing capacity, based not only on the need to preserve their historical origin, but also on the value of the landscape in which they are located. Long-term operation of buildings and their structural elements made of metal without timely maintenance and major repairs, insufficient strength of structural materials, as well as changes in weather conditions and current regulatory documents in Ukraine, often leads to the need to recalculate the load-bearing metal structures of the building frame and strengthen them with the most effective methods, both from the point of view of reliability and from the point of view of profitability, which is influenced by prolonged shutdown of enterprises, stoppage of the production process or the inability to use the adjacent territory to carry out reconstruction work. The article discusses the technological features of metal structures strengthening by gluing high-strength FRP-systems during the reconstruction of building, and also provides basic recommendations for the installation, monitoring and maintenance of strengthened elements.

Modeling of physical wear assessment of zinc coating of space steel frame road structures for road safety information systems

The article developed an improved physical and mathematical model of the corrosive wear of zinc coating of steel structures in a city. The research is based on full-scale experimental data for determining the wear of a zinc coating of full-scale metal spatial structures of frame road structures for informational safety systems on roads after 10 years of operation in the conditions of Kyiv. The frame structure consists of metal columns and a steel crossbar frame. The crossbar frame is a spatial block of two steel trusses. The block of trusses is assembled from unified spatial sections united by vertical and horizontal ties, and which are connected by flange nodes of a special design. All structural elements are made of rolled tubes. Based on the research results, an approach to assessing the physical wear of the zinc coating of the spatial structural system is proposed. According to the peculiarities of the arrangement of elements in frame structures, and, accordingly, to different conditions and operations, an approach is proposed to assess the corrosive wear of a zinc coating for various groups of elements: columns, spatial block of two steel trusses, flange nodes. The physical and mathematical model is based on the working hypothesis of uneven wear of the zinc coating over time. It was found that for each group of structural elements, the conditions of the gaseous environment, the effects of atmospheric precipitation, wind speed, temperature changes individually affect the reduction of the zinc coating. The obtained experimental data were used to determine the parameter of the rate of decrease in the zinc coating of the physical and mathematical model. The results of the research and the development of the methodology helped to establish the operating conditions of the zinc coating according to the criterion of the rate of wear of the zinc coating, to classify the category of aggressiveness of the environment for each group of structural elements. Also, studies allow predicting the service life by reducing the thickness of the zinc coating, as well as the wear of the zinc coating in time in the subsequent period of operation. The methodology is universal and can be extended to other types of galvanized metal structures.

Features of reconstruction of external facade elements

In the materials of the article, the topical issues of reconstruction of the most vulnerable, from the point of view of operation, elements of buildings and structures - load-bearing facade elements, extensions and balconies are considered. The relevance of the research topic is determined by the prevalence of defects of this type of structures arising in the process of construction, operation and refurbishment. Examples of typical design solutions for balconies are given and factors of influence on the lability of building structures of this type are analyzed, depending on the sources of their occurrence and the stage of the life cycle of the building and structure. The types of operational loads and typical deformation processes in the structures of balconies and design solutions aimed at leveling the negative consequences of the impact on structures of environmental factors, organizational and technological errors during construction and operation, as well as a combination of these factors that can lead to a decrease in operational characteristics and bearing capacity of the structures under consideration. The most effective from a constructive, economic and organizational point of view, solutions for the reconstruction and restoration of various types of external elements of facades and balconies have been determined. The article notes the importance of ensuring the compliance of the characteristics of the external elements of facade structures by creating regulations for the maintenance of structures based on state regulatory documents and the methodology for the rational choice of appropriate technology systems for the reconstruction and restoration of a structural element so important for the normal operation of civil buildings and structures as balcony structures of various types.

Features of derivation of formulas for calculation of nodal reactions and coefficients of matrix of rigidity of a finite element with averaged mechanical and geometrical parameters

Currently, the most widely used finite element method for the calculation of spatial structures, significant progress in the development of which is associated with the work of domestic and foreign scientists. In Ukrainian publications the problems of theoretical substantiation of the finite element method and its connection with other methods are considered, concrete types of finite elements and their application to various problems of mechanics of a continuous environment are studied. Much attention is paid to the choice of the appropriate shape of the finite element, the type and degree of approximating functions, as well as the development of methods for deriving stiffness matrices. The study of prismatic bodies with constants along one of the coordinates of mechanical and geometric parameters is most appropriate to carry out on the basis of the semi-analytical method of finite elements. Its essence is a combination of finite element sampling and decomposition of displacements in the characteristic direction by a system of trigonometric coordinate functions. The analysis of the literature shows that the issues related to the application of the semi-analytical finite element method to the calculation of thin-walled prismatic bodies in elastic-plastic, and massive even in elastic formulations, have not been properly reflected. In addition, there are no publications in this area devoted to the development of universal prismatic finite elements that allow you to explore massive, thin-walled and combined structures. The direction of this study is to create on the basis of the semi-analytical method of finite elements of an effective apparatus for numerical analysis of the stress-strain state of massive and thin-walled arbitrarily loaded properties of the material and solve a number of new practically important problems. Therefore, in this work, based on the moment diagram of finite elements, formulas for calculating nodal reactions and stiffness matrix coefficients of a finite element with averaged mechanical and geometric parameters for the study of massive, thin-walled and combined structures are derived.

Fire resistance assessment of RC columns with advanced calculation methods

This paper contains the results of fire resistance calculation of reinforced concrete columns with advanced calculation methods. For columns that are tested unloaded, determine the cross-sectional temperature distribution and values of temperature in reinforcement. The fire resistance of columns that have been tested without load is determined according to temperature measurements, with calculation methods according to the requirements of DBN B.1.1-7 andDBN B.1.2-7. According to the tabulated method, the fire resistance of reinforced concrete columns is determined by geometric parameters such as cross-section width, axis distance of the reinforcement, amount of reinforcement, length or height of the element, load level during the fire exposure, heating conditions during the fire exposure (number of fire exposed sides). Accidental combination of actions during the fire situation consists of characteristic values of permanent and variable long-term actions taking into account the safety factor for the consequence class of the object (CC2) and the type of design situation (accidental). Thermal analysis of the column was performed under conditions of the standard fire exposure. In such conditions it was assumed that the column is exposed to fire with four sides for 120 minutes that corresponds to the required fire resistance class R120. The thermal state of the column was determined using transient thermal models that take into account radiation-convective heat transfer in the ambient from the heat source to the structural surface, convective heat transfer in the structure, radiation-convective heat exchange from the structure to the ambient environment. The residual load-bearing capacity of the reinforced concrete column after the fire exposure was calculated with the reduced cross-section determined using zone method in accordance with the requirements of DSTU-N B B.2.6-197 and DSTU-N B EN 1992-1-2. The fire resistance period of columns for the load-bearing criterion was determined on the basis of the results of of thermal and static analysis.

Interdependence of constructive and settlement schemes of the building

At the design stage is very important for the formation of the reliability of any building is the stage of formation of the design model of the building, which is the basis for the construction of its load-bearing elements. The main at this stage is the adequacy of the adopted calculation model to the actual design scheme. A very important condition for assessing the actual operation of the building is to take into account the joint work of the upper part of the building (frame) with the foundations and soil base. The article examines some problems in the operation of structures, which are related to the choice of design models used in their design, on the example of a 9-storey parking lot built in the early 2000s on Pobeda Square in Kyiv. Chi-rural studies using PC LIRA-CAD analyzed the impact of joint work of the framework and foundations on the efforts at their contact. It was found that: - the impact of joint work of the frame and foundations is significant and is manifested only within a few lower floors of the frame; - taking into account the nonlinear operation of reinforced concrete structures in most cases significantly reduces the calculated forces at peak points - concentrators; - in the design process it is necessary to consider and analyze the variant design solutions of the system.