Fundamental education in a construction university (to those beginning their professional education)
Pages 5-6
DOI: 10.22227/1997-0935.2015.7.5-6
Articles count - 16
Pages - 157
Pages 5-6
DOI: 10.22227/1997-0935.2015.7.5-6
Pages 7-16
Historical architectural buildings carry features of different culture layers, it exhibits specific character of places and urban matrix, play leading role in cultural succession of different epochs. Investigation, use and the existence itself of historical objects in the modern city architecture is a factor of national identity formation. Lack of due attention to the problem of historical buildings preservation will have a negative impact on the material and spiritual spheres of human life. That’s why preservation of historical architectural environment of the city is one of the most important tasks of the contemporary society. The authors analyzed technical, law and urban planning aspects of historical buildings’ functioning in the conditions of developing construction in the central city areas and constant increase of structural, economical, hygienic requirements to buildings. The technical state and possibilities of adjusting the buildings-monuments, which have preservation category, and buildings without such status are compared, as well as their role in cohesive architectural environment formation.
DOI: 10.22227/1997-0935.2015.7.7-16
Pages 17-24
The equations of the finite element method for calculation of sandwich shells taking into account creep were obtained. The shell is represented as a set of flat triangular elements. The thickness of the carrier layers is supposed to be small compared to the total thickness of the shell. It is assumed that the outer layers perceive normal stresses, and the average layer perceives the shear forces. In the derivation of governing equations we used variational Lagrange principle. According to this principle, the true moves of all the possible ones satisfying the boundary conditions, are the ones that give a minimum of the total energy. Total energy is the sum of the strain energy and the work of external forces. The problem is reduced to a system of linear algebraic equations. On the right side of this system there is the vector of the sum of the external nodal forces and the contribution of creep strains to the load vector. The calculations were performed in mathematical package Matlab. As the law for description of the relationship between stress and creep strain, we used linear creep theory of heredity. If the core of creep is exponential, the creep law can be written in differential form. This allows the calculation by step method using a linear approximation of the time derivative. The model problem has been solved for a spherical shell hinged along the contour. The relationship between the curvature of shell and the growth of deflections was analyzed. It was found out that for the shells of large curvature the creep has no appreciable effect on the deflections.
DOI: 10.22227/1997-0935.2015.7.17-24
Pages 25-32
A great number of works have been written on the frequencies of spherical bodies. In construction hollow balls are widely used. For this reason it is important to investigate the dynamics of such bodies, in particular, their resonance oscillations. In the paper we obtained an equation for determining the resonant frequencies of axisymmetric oscillations of a hollow ball. The general solution of three-dimensional equation of motion is used in a spherical coordinate system. Frequency equations of purely radial oscillations of solid and hollow balls are given as special cases. These equations coincide with those obtained previously. The solution may be used in boundary problems for arbitrary loaded space bodies, all the three dimensions of which are relatively equal, in the dynamic tasks for high-frequency oscillations.
DOI: 10.22227/1997-0935.2015.7.25-32
Pages 33-40
The kinetic theory of gases is considered as a collection of a large number of interacting particles. We consider the discrete kinetic model of one-dimensional gas consisting of identical monatomic molecules, which can have one of two speeds, namely, the Cauchy problem with periodic initial conditions for the system of the Carleman equation. This mathematical model has a number of properties of the Boltzmann equation. This system of equations is a quasi-linear hyperbolic system of partial differential equations. In general, there is no analytic solution for this system. Therefore, under some general assumptions we can find the finite-dimensional approximation of the solutions for the Carleman equation with small Knudsen numbers that allow us to study our problem on the widest scale. Moreover, we can find the secularity condition of the Carleman model. An approximation solution of the Carleman equation for non-periodic initial data will be found in the next article. There is an interesting problem of the existence of the shock waves connecting the pairs of equilibrium states. Here we have a catastrophe theory. It is assumed that the solutions of the Cauchy problem split into the superposition of weakly interacting solitons and decreasing dispersive waves. The Cauchy problem of the Carleman equation is studied for small perturbations of the equilibrium state whereby we have perturbed system. In order to construct the finite-dimensional approximation we use the Fourier method. Construction of finite-dimensional approximation allows doing theoretical studies of solutions for the Cauchy problem of the Carleman equation with small Knudsen numbers.
DOI: 10.22227/1997-0935.2015.7.33-40
Pages 41-46
This article is devoted to the peculiarities of calculating deformability modifications of the timber elements on mechanical linkages. Here we analyze in detail the method of V.M. Kochenov used in the design standards of the Russian Federation. This method allows accurately determining the number of links that are able to resist the shear force in the linkage, however, this method does not include analyzing of shear deformation in modifications. And it is an important disadvantage. In this article the author considers another approach, based on the idea of determining the shear deformation of the mechanical linkage, installed in the connection. In order to calculate the shear deformations of the connections in the linkage it is necessary to conduct a preliminary analysis of the construction, to establish the type of connection and the thickness of the connected elements, to determine the number of slice planes, the number of established connections and the load level on the connection. After determining these values, structural analysis design is performed. This article describes in detail the theoretical aspects of this method, used assumptions and limitations. A test case is considered for validation of the considered methods.
DOI: 10.22227/1997-0935.2015.7.41-46
Pages 47-56
In this paper the problem of interaction between grouted anchor and the surrounding soil body with account for its elastic-plastic properties is solved by analytical and numerical methods. Tensile loads are exerted on a grouted anchor placed in homogeneous soil body. Under ultimate loads occurs the failure of the system “anchor-surrounding soil”. This research is based on the elastic-plastic model designed by Timoshenko. The problem of interaction between grouted anchor and the surrounding soil is solved in various design conditions, such as constant structural shear strength, account for anchor stiffness, linear variable structural shear strength. The solutions of these problems can be used for quantitative estimation of the stress-strain state of the system. This estimation makes it possible to calculate the displacements of anchors and their bearing capacity. It is shown that displacements significantly depend on physico-mechanical properties of the surrounding soil, geometrical properties of the anchor, selection of design model. The analysis demonstrates that load-displacement curve has clear nonlinearity and unrestrictedly increases at approaching the ultimate stress. The account for anchor stiffness insignificantly influences the obtained solutions and account for it may be neglected. The obtained equations also show that the displacement of the anchor increases with widening of the diameter at constant dimensional ratio of the cylindrical model. It is demonstrated that the ultimate uplift capacity is dependent on the dimensions of anchors and physico-mechanical properties of soil. Analytical solutions are compared to the results of the Finite Element Analysis (FEA) in the computer program Plaxis. The comparison of analytical and numerical solutions has close precision for the magnitude of anchor displacement and ultimate loads.
DOI: 10.22227/1997-0935.2015.7.47-56
Pages 57-68
A diaphragm wall is a highly effective way to erect building substructures in urban conditions. A diaphragm wall construction minimizes urban environment violation, prevents air, surface and groundwater pollution, ensures firmness of the closely located buildings, their foundations and engineering services, and prevents settling of the ground and its surface. Geotechnical monitoring in the process of diaphragm wall construction allows revealing the influence and progress of unfavourable factors during the building activities in the conditions of the existing historical development. In the given article the current composition of geotechnical monitoring while constructing “diaphragm wall” in restricted conditions is considered. Its role in assuring safety of the construction object and the environment is discussed.
DOI: 10.22227/1997-0935.2015.7.57-68
Pages 69-78
Composite materials for building structures have certain advantages. In this field Russian scientists got patents for inventions and useful models of new construction materials and structures. Scientific investigations on determining deformation capacity of concretes and building structures of other materials (wood) and their limit states are continuing with account for force and environment impacts and degradation weakening of construction elements. The article presents the study of physical and mechanical properties of composites based on liquid glass, depending on their quantitative and qualitative composition. The properties of the composites based on liquid glass depend on the type, quality of the composites in the material, their durability, correlation of their strength properties, adhesion of binders and filler, etc. In the studied composites different filler content, hardener, as well as modifying additives were used, that improve the properties of materials.
DOI: 10.22227/1997-0935.2015.7.69-78
Pages 79-86
The problem of nanocomposites’ permeability regulation has been attracting the interest of scientists throughout the current decades. The works were dedicated to different models of permeability of the composites containing impermeable layered fillers in polymer matrix. It was shown that polymer films with parallel laid flat impermeable particles of the filler may have the permeability twice or thrice less than the films of the same size, but without a filler. The authors analyzed the influence of nanoparticles on water permeability through nanocomposites obtained on the basis of polymers and flat nanoparticles. The offered correlations take into account the chemical composition of the polymer and nanoparticles, as well as the surface structure in case of chemical modification. The shape of flat particles (tablet, brick, sphere) is also taken into account. The permeability is mostly influenced by nanoparticles concentration, their shape and size orientation angle.
DOI: 10.22227/1997-0935.2015.7.79-86
Pages 87-104
Swirled flows of liquid and gas are widely used in modern technology because of many of their unique aerodynamic, thermodynamic, and hydro-mechanical qualities. They are used for spraying liquid fuel mixing and dispersing liquid, aerosol formation, formation of the flame, classification of disperse materials and drying, dehydration, deaeration, cooling and heating, distillation and purification (rectification of working fluids), ash and dust-collecting, generating vapor separation of suspensions, absorption materials, separation materials, excitation of mechanical vibrations and formation of a sound signal, transportation of materials and many other technological purposes. The proposals for the use of interacting (counter vortex) swirling flows were caused by the requirements of the practice of mixing fluids and gases and quenching of excess kinetic energy of the high-speed flow of water in the high-pressure hydro spillways. The method for energy dissipation by reacting flows (jets) I based on the idea of separating the stream into parts and creating the conditions for mutual energy damping of individual parts of during subsequent reunification. As it is known, while moving from the upper pool to the lower one the water flow may dampen its energy performing useful work on the hydraulic turbines or overcoming the reaction forces, which arise when passing through the dampers. The energy of one part of a stream in interaction with the energy of the other part is used for creating the forces equivalent to the jet forces developed by quenchers. Such interaction can give the best effect in the conditions of rational breakdown of a stream and creation of the respective movement directions of its parts in relation to each other. In the cylindrical camera of counter vortex devices coaxial flows are formed consisting of two or more oppositely swirling flows of liquid or gas, the interaction of which can convert practically the whole mechanical energy source of the interacting flows into excess turbulence energy. The nature and intensity of hydro-mechanical, aerodynamic and mechanical processes occurring in the counter vortex devices provide the efficiency of their application in various branches of modern technology for mixing of single-phase and multiphase media, quenching the excess mechanical energy of the flow of liquid and gas, for disintegration of conglomerates, creating a homogeneous systems, excitation of mechanical vibrations and obtaining other effects. Authors due to the nature of their activity paid the main attention to the development, researches and creation of the designs of counter vortex quenchers of spillways energy of high-pressure water-engineering systems and counter vortex aerators of different purpose. Counter vortex devices have been tested for other purposes (homogenizer, flotators), protected by patents or circuit diagram are proposed for them.
DOI: 10.22227/1997-0935.2015.7.87-104
Pages 105-112
In most cases the parameters of a pipeline are calculated on the basis of of the Darcy formula, which is true for steady-state fluid motion. However, for the study of the dynamic mode of fluid motion it is necessary to use the method of transfer functions. In this method the processes should be described not only by using mathematical formulas. Also a phased definition of transfer functions is required. In this case, it becomes possible to perform continuous automatic analysis of the quality of various piping systems. The theory of automatic control allows presenting the basic formulas in the form of a scheme of regulation.
DOI: 10.22227/1997-0935.2015.7.105-112
Pages 113-126
Today the national economy is facing the need of modernization. There is a problem of its transfer to an innovative way of development. The construction complex is one of the most important sectors of national economy. Now its innovative and technological rearmament is necessary. Creation and introduction of new technologies in a construction complex will allow improving the quality of construction production, its consumer characteristics, reliability and ecological safety. Also application of innovations in construction will provide energy efficiency of buildings and constructions. Application of institutional approach to the process of innovative development of a construction complex allows understanding better features of its functioning in modern conditions. In the article the institutional approach to innovative development of a construction complex is considered. The control system of innovative development of a construction complex with the use of innovative engineering from the point of view of institutional approach is considered. Its advantages are revealed and proved.
DOI: 10.22227/1997-0935.2015.7.113-126
Pages 127-136
The given article shows the peculiarities of project management methods, 3D-modeling, scheduling-network planning, straight-line organization of work, visual modeling of construction arrangement, norm setting and cost estimation of work. After all, applying the methods mentioned above should provide earlier and less resource-consuming solution of the problem of constructing facilities within limited time and costs at permanent performance property as well as requirements for safety and quality. Hereinafter, the article summarizes the studied methods’ functionality together with the coverage areas’ analysis, and the above listed methods limitations are described, when they are used on a stand-alone basis. The list of tasks to be solved during elaboration and optimization of organizational and technological solutions is formulated on the basis of the analysis of regulations and project organization, elaborated on their basis. The conclusion was made a on the possibility of achieving best results by using these methods collaboratively, assuming that these methods would be complemented with the methods of economic assessment variation of architectural, engineering and organizational and technological concepts, and also with the help of methodology of searching for the most favorable solution in accordance with the criteria of economic efficiency. At the end of the article the information on the studies’ continuation is provided. Thus, the functional model that provides the search of the most favorable solution for the capital construction’s value and duration, based on harmonization of architectural, engineering, economic, financial, resource-technological and organizational-technological solutions is described in the author’s article : “The concept of economic-visual model building, an instrument of improving the investment and construction realization efficiency”.
DOI: 10.22227/1997-0935.2015.7.127-136
Pages 137-146
In civil engineering and architectural design the coupling of circular curves are of great importance. There are different requirements for their practical application, including the possibility of approximation of the curves of higher order. The present article contains a brief excursion into the axiomatic description of the properties and concepts uniting the geometric graphics of a circular, a direct and a point into various compositions. One of the main conjunction theorems is presented, which defines the position and properties of orthoelements of pairing and the sequence of mating arcs using symmetry. The content of the theorem is commented in the form of proof by contradiction, in the form of geometric graphical operations that are naturally consistent with the analytical results. The examples are given of the circular conjunctions closed into oval shapes with a slight difference in the algorithms of composition construction. A particular case of the present configuration is a linear model of squaring the circle, the circle when the medial conjunction coincides with the base circle squaring. Here, the rhomb figure is presented as a basic square and the four successively conjugated circles have their centers at the vertices of squaring, their area are equiareals. Then, the straight “tapered” circular number and variations of its geometry graphical construction are analyzed. The summary results of the considered material are as follows. The main qualitative, quantitative, and typical examples of the circular conjunctions allow competently and variably solving certain problems of geometry graphics in the design process of civil engineering, architecture and applied domestic objects, items and personal things.
DOI: 10.22227/1997-0935.2015.7.137-146
Pages 147-157
One of the main aspects of architectural education is development of the sequence, an algorithm of design, generation of space and planning solution with account for all the limiting factors and requirements. In different periods of society and science development the process of architectural design, its aims and methods have been changed. For example in the 20th century the most important thing was correspondence of buildings and structures to everyday and industrial requirements. At the present time in general the architectural society came to the conclusion that the form and the function are closely related and influence each other. The article highlights the following aspects of current architectural design process: the initial data and design task influence on the method selection, the problem of form and function relation, contemporary trends in searching the form. Two basic methods are exposed: “from the form to the function” and “from the function to the form”. The article uncovers the design phases and shows different elements’ impact on each phase.
DOI: 10.22227/1997-0935.2015.7.147-157