Статьи журнала - Строительство уникальных зданий и сооружений
Все статьи: 774
Статья научная
The object of the research is a planar, statically determinate girder of the beam type with a triple diagonal lattice.The truss mass is modeled by equal masses distributed over the nodes of the lower chord. By the Dunkerley method, under the assumption of vertical vibrations of loads, a lower analytical estimate of the first natural vibration frequency is obtained. Method. The forces in the members are calculated by cutting out nodes from the solution of a system of linear algebraic equations. Generalization of individual solutions to the case of an arbitrary number of panels is carried out by the induction method with the involvement of operators of the Maple computer mathematics system. Results. Comparison with the numerical solution found from the solution on the spectrum of natural vibrations of a multi-mass system shows that the estimation accuracy depends on the number of panels and varies from 16% for trusses with two panels to 4% for trusses with more than 11 panels. With a decrease in the ratio of the panel height to its length, the accuracy slightly increases. Based on the analysis of the derived formula, it is shown that the dependence of the first frequency on the height of the truss has a maximum. An algorithm for generalizing the solution to the case of members of different stiffness is proposed.
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The influence of the temperature and the structure of snow on the roof covering
Статья научная
Analysis of the highest snow load is important in the process of designing of a roof structure. It is also necessary to take into account a coefficient of snow friction in addition to the main stages of calculation. This parameter may depend on the structure and temperature of the snow and the coating material. The dependence of the friction coefficient of these parameters were determined using techniques developed by research and testing laboratory “Polytech-SKiM-Test” with using of tribometer. Various snow conditions and two types of roof coverings - PVC-tent and Pural were considered in the research. The results of experiments are the dependencies of the coefficient of friction on various materials and slipping speeds. Moreover, values of frictional forces of the snow on the coating at different temperatures were defined.
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The method and computation of air change required for attic rooms
Статья научная
The article deals with the recommendations how to eliminate ice dam formation on pitched roofs of the buildings with cold attics during heating period. The case of how to calculate required air change in cold attic rooms, where building structures which separate attics from rooms or utilities with high temperature (heat supply sources) are not insulated, is given in details. It is proved that natural ventilation system can ensure this condition only within short terms. It is necessary to both carry out works to ensure air change and insulate building envelopes, which separate cold attics from rooms with higher air temperature in order to satisfy all the requirements to eliminate reasons of ice dam formation on roofs
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The most effective crushing equipment and testing of recycled concrete aggregates
Статья обзорная
The goal of this research is to study the international experience in managing the construction and demolition waste, to study the methods of testing recycled aggregates for concrete and reinforced concrete in comparison with the Russian practice, and to identify the most effective equipment for concrete waste recycling. Recycling of concrete waste could be the optimum solution for such problems as the lack of space for construction, the exhaustion of natural resources etc. The comparative analysis of the results of different researches showed, that up to 50% of recycled concrete aggregates of total amount of aggregate in concrete mixture has a little effect on the properties of concrete. The recycled aggregates are in demand, because they cost much lower than that the natural aggregates. The analysis of technical and economical qualities of different types of crushers showed, that swing-jaw crushers with their crossfunctionality and power are best for reutilization of concrete and reinforced concrete. Requirements for the type of the crusher depend on the utilization project of the particular building or construction, because each case is unique.
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The pressure loss and the filtration coefficients in pipelines with grids
Статья научная
A variety of grids and lattices that occur in different spheres of practical activity requires detailed study. The presence of these devices leads to additional resistance and energy losses during their flow. The paper discusses a flat plastic perforated mesh with different degree of permeability at the outlet of the pipeline. The coefficients of grid resistance were determined experimentally. The effect of grids on the total head loss were established through the presence of resistance coefficients volume method at fixed pressure: we determined the flow at the exit of the horizontal pipe of constant cross section, the end of which was mounted the investigated grid. To precise definition, the obtained values along with the experiments on the measurement of costs used a method of determination using piezometers: according to the length of the flow part were installed piezometers and the values of the coefficients of resistance were established on the basis of differential pressure. The identity of the two methods of determining the resistance coefficients is shown, in terms of flow rate and pressure drop on the grids. The effect of grids on the capacity of the pressure pipeline has been established: the replacement of the flow part does not affect to the numerical values of resistance coefficients of the grids. The dependence of the relative flow rate in the pipe on the surface porosity of the grids is obtained; this dependence gives a qualitative estimate of the reduction in the capacity of the pipe in the installation of meshes. The experimental data for constructing this dependence agree with the calculations for the approximating dependence established earlier. The transition from resistance coefficients to filtration coefficients and permeability of the pipeline with grids is suggested, because it is more convenient in practical calculations by characteristics. Graphs of the permeability coefficients dependence, related to the pipe cross-section area, and the filtration coefficients on the surface porosity of the grids are given. The proposed dependencies are linear functions of the surface porosity.
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The stress-strain state of a rectangular covering spatial truss
Статья научная
The object of research is a model of a statically definable roof truss with supports on the sides of the structure. Spherical and cylindrical supports are located at two corner points of the covering, in other corners and on the sides of the structure at an equal distance from each other - stands. A multi-dome surface shape is set. For the case of loading the truss by the force in the middle of the span by the induction method according to the number of panels, the formula for the deflection is derived. Analytical dependencies of the reactions of supports on the number of panels under the action of a load uniformly distributed over the nodes of the coating surface are found. Method. The calculation of the forces in the rods and the reactions of the supports of an externally statically indeterminate truss is performed in symbolic form using the method of cutting nodes. To compose a system of equilibrium equations and obtain a solution, the operators of the Maple computer mathematics system are used. The deflection is determined by the Maxwell-Mohr's formula. Based on the data on the solution of a series of trusses with a sequentially increasing number of panels by the induction method, formulas for the dependence of the deflection on the load, the size and number of panels of the structure are derived. Operators of the genfunc software package from the Maple computer mathematics system are used to compose and solve homogeneous linear recurrent equations, which are satisfied by the sequences of the coefficients of the sought dependencies. Results. Dependences of deflection and forces on the number of panels have a form polynomial in the number of panels. It is shown that the vertical reactions of the corner supports can have negative signs, which makes it necessary to use retaining supports here. The curves illustrating the solution have a clearly pronounced jump-like shape. The quadratic asymptotics of the solution is found both in terms of the number of panels and linear in height. The dependence of the deflection on the height has a theoretically permissible minimum. The considered scheme of a spatial statically definable roof truss allows an analytical solution to the deflection problem. The obtained dependences can be used to estimate the accuracy of numerical solutions and in problems of optimization of the structure in terms of rigidity and solutions.
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Translucent elements as structural part of facade systems
Статья научная
The objects of research are translucent elements in curtain wall systems, which are common modern architectural and structural solutions. Method. To determine the stress-strain state of a translucent element as part of curtain wall systems, different calculation methods are applied to calculate insulating glass units under full wind load. These methods are based on recommendations from regulatory documents, Navier Solution and numerical experiments in Mepla ISO program and ANSYS software package. In calculations, insulating glass units have different values of linear dimensions, glass thickness and air gaps. The deformation characteristics of a two-component sealant are determined by testing the material in an experimental setup. Results. Based on the results of the work, the convergence of the methods with each other is considered, and the glass unit with the smallest deformation values in the outer glass from the action of wind loads is determined.
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Trihedral rod pyramid: deformations and natural vibration frequencies
Статья научная
The object of research is a new truss scheme of a statically determinate dome structure. The purpose of the study is to derive formulas for the dependences of the deflection under the action of a uniform load and the first frequency of natural vibrations on the number of panels, sizes, and masses concentrated in the truss nodes. Method. The forces in the truss rods are found from the equilibrium equations of the nodes. The system of equations also includes the reactions of vertical supports located along the contour of the structure. It is shown that the distribution of forces over the structure rods does not depend on the number of panels. The deflection values and stiffness of the truss structure are calculated using the Maxwell - Mohr formula. The lower analytical estimate of the first frequency is obtained by the Dunkerley method, the upper one by the Rayleigh energy method. As a form of truss deflection in the Rayleigh method, the deflection from the action of a uniformly distributed load is taken. Only vertical oscillations of the weights are assumed. Results. The dependence of the solution on the number of panels is obtained by generalizing a series of solutions for trusses with a successively increasing number of panels. The solution uses operators of the Maple computer mathematics system. Graphs of the dependence of the deflection on the number of panels for different truss heights are plotted. The horizontal asymptote of the solution of the deflection problem is found. The value for the first natural frequency is compared with the numerical solution obtained from the analysis of the entire spectrum of natural frequencies of the vertical oscillations of the mass system located in the truss nodes. The frequency equation is compiled and solved using the eigenvalue search operators in the Maple system. It is shown that the lower analytical estimate based on the calculation of partial frequencies differs from the numerical solution by no more than 37%, while the upper estimate has an error of 7%. In this case, the formula for the lower Dunkerley frequency estimate turns out to be more compact. The natural frequency spectrum of the truss is analyzed. Isolines were found in the set of frequencies for a series of regular trusses.
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Unconventional cases of the stone vaults
Статья научная
The evaluation of the technical condition of vaulted structures is the principal issue in the survey of historical buildings. It is also important to understand how any thrust system works, and what functions it performs. However, apart from visual inspection it is necessary to make apertures in vaulted ceilings and determine the methods of support. It is also very important to determine the strength characteristics of masonry. Unconventional cases should always be taken into account during the inspection of masonry vaulted structures. It needs to carefully conduct their inspection with the mandatory breaking opening and strength analysis based on numerical simulation before starting of all the reconstruction, restoration and repair. The use of modern program complexes in the simulation, such as Ansys, Abaqus, allows improving the quality of performed work
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Water surface and drainage area measuring with satellite navigators
Статья научная
There are several geodesic methods of area measurement. The following article provides description of a non-conventional method which involves the usage of satellite navigation devices. Based on a practical research, the accuracy of the method is being estimated. The analysis of different measuring conditions and factors, regarding their effect on accuracy, is made. The suitable areas, where the method could be used, are mentioned. In particular, the possibility of water surface and drainage area measuring is examined with the usage of previous theoretical base. In addition, the results of a recent field check covering such type of areas are presented in the article.
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Wood-composite structures with non–linear behavior of semi-rigid shear ties
Статья научная
The object of research is composite structures with semi-rigidity ties, such as ribbed steel-concrete and wood-concrete floors, and structures based on structural wood and wood-composite materials, which are widely used in industrial and civil building. As a rule, various types of mechanical ties are used as shear ties in composite structures. In calculations of such structures according to the classical method, the behaviour of shear ties is generally assumed to be linear-elastic. It does not make it possible to consider the real character of the deformation of the ties during shear force action. Method. The presented calculation algorithm is based on the solution of A.R. Rzhanitsyn for the differential equation for the two-layer composite rod. Separating the element into sections and set the boundary conditions at the borders of the sections, a system of linear equations can be obtained from which the values of the shear forces T and integral constants can be determined. This approach makes it possible to determine forces in the shear ties and normal stresses in the layers in any cross-section of the composite element. As an example, a two-layer composite beam is considered, the layers of which are connected by cylindrical nails, the deformation of which occurs according to non-linear behaviour. Results. it was concluded that the calculation according to the classical method, taking into account linear behaviour of ties, gives an error of up to 25% while the shear force in the ties determining and up to 111% when normal stresses in the layers of the composite beam were determining. Such errors do not make it possible to get a reliable estimation of the strength of materials and shear ties of the composite structure
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World ecological problems and their solutions by the sustainable architecture
Статья научная
The paper shows actual ecological problems, reveals the causes of the “greenhouse effect” and sorts out, who is to blame for the climate changes and other issues, caused by the human activity all over the world. The influence of a mankind on the world’s ecology during the past hundred years is hard to overestimate, and the biggest part of the guilt lies upon the developed countries, while the whole world suffers the consequences. In near future, urbanization of the humanity won’t reduce, besides, it will develop fast and the predictions made by the analysts say that by the 2050 85% of people will live in the cities. But there is much that we can do for our planet, without rejecting the technological progress benefits, and even urbanization can be “green”. This article shows the ways of improving our life quality by applying the ecological design methods to the building construction sphere
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XXIII Ениколоповские чтения. Наноматериалы: теория и практика
Статья
Резюме. XXIII Ениколоповские чтения состоялись 13 марта 2015 года в Институте Синтетических Полимерных Материалов (ИСПМ) им. Н.С. Ениколопова РАН.Эти чтения были организованы Отделением Химии и Наук о Материалах РАН, Научным Советом РАН по Высокомолекулярным Соединениям, Институтом Химической Физики им. Н.Н. Семенова РАН и ИСПМ РАН. Более 180 ученых из 25 исследовательских центров приняли участие в работе этой конференции.
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Статья научная
This paper presents an analysis of the „Performance-Based“ seismic design method, in order to overcome the perceived disadvantages and limitations of the existing seismic design approach based on force, in engineering practice. Bearing in mind, the specificity of the earthquake as a load and the fact that the seismic resistance of the structures solely depends on its behavior in the nonlinear field, traditional seismic design approach based on force and linear analysis is not adequate.„Performance-Based“ seismic design method is based on nonlinear analysis and can be used in everydayengineering practice. This paper presents the application of this method to eight-story high reinforced concrete building with combined structural system (reinforced concrete frame structural system in one direction and reinforced concrete ductile wall system in other direction). The nonlinear time-history analysis is performed on the spatial model of the structure using program Perform 3D, where the structure is exposed to forty real earthquake records. For considered building, large number of results was obtained.It was concluded that using this method we could, with a high degree of reliability, evaluate structural behavior under earthquake. It is obtained significant differences in the response of structures to various earthquake records. Also analisis showed that frame structural system had not performed well at the effect of earthquake records on soil like sand and gravel, while a ductile wall system had a satisfactory behavior on different types of soils.
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«Битва технологий» на 17-ой Международной строительной выставке BalticBuild
Ред. заметка
С 11 по 13 сентября 2013 года в Санкт-Петербурге проводилась 17-ая международная строительная выставка BalticBuild. В центре внимания участников и гостей выставки оказалась дискуссия под названием «Битва технологий». Конкуренты пяти сегментов рынка строительных материалов и технологий представляли свою продукцию, отстаивая право быть признанными лучшими.В «битве» сражались: ООО «Альянс Трейд» и «Невская Эковата», ООО «Центр европейских технологий» и ООО «ЗИКА», ЗАО «ЭнергоКапитал» и Представительство НПП «Белкотломаш», ООО«ИТЭС» и ООО «Русские герметики», ЗАО «Стройкомплект» и ДРиМ ООО ФПГ «РОССТРО».Директор Инженерно-строительного института ФГБОУ ВПО «СПбГПУ», доктор технических наук и профессор Николай Иванович Ватин взял на себя ответственную роль модератора одной из дискуссий. По его мнению, «битва технологий» позволила выявить слабые места продукции и представить её в более доступном для зрителя формате, нежели реклама.В заключении также отмечено, что дискуссия оправдала ожидания участников, подтолкнув их к улучшению качества представленной продукции.
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«Зеленое» строительство в России и за рубежом
Статья обзорная
Считается, что основной причиной глобального потепления является технический прогресс. Техносферная деятельность человека приводит к росту содержания в атмосфере парниковых газов за счет все большего сжигания топлива, что является фактором, повышающим температуру. Климатические аномалии провоцируют социальные катаклизмы. Важнейшей задачей на современном этапе является снижение глобальных рисков и повышение безопасности людей. Эффективным инструментом повышения устойчивости среды обитания является строительства «зеленых» зданий. В данной статье выполнен аналитический обзор современной направленности работ в области «зеленого» строительства в России и в зарубежных странах. Рассмотрены основные принципы «зеленого» строительства, концептуальные основы зданий с низким энергопотреблением. Показано, что «зеленые» крыши и «зеленые» фасады являются важными элементами формирования экологически устойчивой архитектуры и энергосберегающего строительства. Рассмотрены проблемы повышения энергоэффективности при термореновации фасадов зданий. Рассмотрены принципы рейтинговой оценки в «зеленом» строительстве. Полученные результаты имеют важное практическое значение. Систематизация и обобщение данных по «зеленому» строительству позволяют наметить дальнейшие пути повышения энергоэффективности и экологической безопасности зданий и сооружений при решении актуальной проблемы повышения устойчивости среды обитания в градостроительстве и архитектуре.
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«Тепловой байпас» или движения воздуха, вызывающие значительное увеличение тепловых потерь
Статья научная
Целевое сокращения выбросов СО2 на национальном уровне до 80% и необходимость создания«безуглеродных» зданий привлекли внимание специалистов в области проектирования и оснащениязданий. Появление «теплового байпаса» оказывает значительное влияние на совершенствование конструкции для развития жилищного строительства, что приводит к развитию новой системы обеспечения качества. Следует признать, что термин «тепловой байпас» в основном относится к неизвестной и часто нерегулируемой теплопередаче. В этой статье рассматриваются некоторые принципы устранения воздушных зазоров внутри и по обе стороны от изоляционного слоя, чтобы сохранить герметичную конструкцию, а также для защиты изоляционного слоя от ветрового движения воздуха.
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Абразивная стойкость асфальтобетона
Статья научная
Абразивный износ композитов является одной из причин разрушения материалов, необходимо оценить методы оценки абразивного износа композитов. Предметом исследования является расчет стойкости к истиранию асфальтобетонов.
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Автоколебательный процесс вязкоупругой удлиненной пластины
Статья научная
Объект исследования. Рассмотрен автоколебательный процесс вязкоупругой удлиненной пластины, движущейся в стационарном сверхзвуковом потоке газа, с учетом геометрической и аэродинамической нелинейностей. Разработаны математическая модель, методика, вычислительный алгоритм и программа расчета на персональном компьютере для оценки флаттера вязкоупругой удлиненной пластины в потоке газа. Метод. С помощью метода Бубнова-Галеркина, основанного на полиномиальной аппроксимации прогибов, задача сводится к решению нелинейного интегро-дифференциального уравнения типа Вольтерра с сингулярным ядром релаксации, которое решается численным методом, основанным на использовании квадратурных формул, что устраняет особенности в ядре релаксации. Полученные результаты. Представлены результаты расчетов линейного и нелинейного флаттера для различных физико-механических и геометрических параметров вязкоупругой удлиненной пластины. В результате исследования установлено, что учет геометрической нелинейности приводит к увеличению, а учет вязкоупругих свойств материала к уменьшению значений критической скорости, при этом реологические параметры вязкости А и сингулярность α оказывают существенное влияние на значения критической скорости, а влияние третьего реологического параметра β незначительно.
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Автомобильные стоянки и парковки в мегаполисах
Статья обзорная
В настоящее время одной из самых актуальных проблем мегаполисов является перегруженность автомобилями, количество которых увеличивается с каждым годом. Дефицит парковочного пространства выдвигает задачу комплексного решения управления парковками. Это приводит к поискам новых решений, обладающих инвестиционной привлекательностью и нацеленных на увеличение эффективности функционирования автомобильных парковок. В статье проведен краткий обзор наличия мест стоянки автомобилей в городах, приводятся основные проблемы их применения и пути решения.
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