Unified technological system of a building and current problems of educating specialists in construction
Pages 5-6
Articles count - 13
Pages - 137
Pages 5-6
Pages 7-16
The recent decade has been the time of the rapid development of communication infrastructure, but very often the structures erected in the middle of the last century are used as a basis for new transmission units and antennas, which are considerably worn out. In this regard the control problems of the infrastructure facilities such as towers and masts are often emerging. Such tasks may be associated with the test required when installing additional equipment and modules, as well as during the scheduled inspection and certification of individual objects in accordance with the legal documents. Timely detection of critical deformations will to a large extent prevent the occurrence of accidents and disasters. For accurate detection of deformations load cells on the basis of the piezoelectric effect and fiber-optic sensors based on Bragg gratings are most commonly used, but in such distributed information measurement systems there are significant drawbacks, which narrow the scope of their possible application. Among the main disadvantages there are: high cost of initial installation and configuration, and the subsequent operation of such systems. Traditional measuring sensors require power, separate line of measurement information signal, as well as lines for supplying control signals. A significant limitation is that any sensor detects deformation or other parameters of the design only for its whole base, thus, active sensors should be installed in structures, in which an altered state was detected by visual inspection or by other means. The emergence of video and photo-detectors with high resolution and other settings to get a high-quality image of the object made it possible to establish the systems for infrastructure objects’ monitoring with the characteristics acceptable for practice. At the heart of such systems there are not only detectors with high sensitivity, but also the algorithms for the objects’ recognition, determination of their geometrical parameters by analyzing a series of images. This is the issue and the subject of this work, which developed the computational algorithms to detect external defects. At the stage of preliminary image processing there is the delineation of characteristic points in the image and the calculation of the optical flow in the area of these points. When determining the defect position, the characteristic points of the image are determined using the detector of Harris-Laplace, which are located in the central part of the image. The characteristic points outside the frame are considered to be background. There is an identification of the changes in characteristic points in the frame in relation to the background by using a pyramidal iterative scheme. In the second stage servo frame focuses on a specific point with the greatest change in relation to the background in the current time. The algorithm for object detection and determination of its parameters includes three procedures: detection procedure start; the procedure of the next image processing; stop procedure for determining the parameters of the object. The method described here can be used to create information-measuring system of monitoring based on the use of photodetectors with high-definition and recognition of defects (color differences and differences in the form compared to the background). Since almost each examination of a building or structure begins with a visual examination and determination of the most probable places of occurrence and presence of the defects, the proposed method can be combined with this stage and it will simplify the process of diagnosing, screening for the development of projects on reconstruction and placement of additional equipment on the existing infrastructure.
DOI: 10.22227/1997-0935.2015.3.7-16
Pages 17-28
The construction quality of road surface of non-rigid type essentially depend on providing the temperature regimes in the process of laying and packing of hot asphalt concrete mixtures. In order to provide the required characteristics of asphalt concrete due to the surface width it is necessary to provide the temperature regimes of hot asphalt concrete mixture in the zones of lane connection. The hot mixture is promptly cooling right after laying within several minutes, which results, according to the construction technology and the specific conditions of work production, in temperature abuse of the mixture at joints of the lanes at packing. The authors present the analysis of the technology of arranging multilane road surface by one paver with the possibility of heating the surface lane edge with the temperature of the adjacent lane. The results of the studies of the production conditions effect on the temperature of edge heating of the previously laid lanes, and the time required to achieve the maximum heating temperature depending on the relative thickness of coating layers.
DOI: 10.22227/1997-0935.2015.3.17-28
Pages 29-39
In order to prolong the lifetime and to improve the quality of pavements made of asphalt concrete it is necessary to apply innovative solutions in the process of design of such building materials. In order to solve the problem of low durability of asphalt concrete a modifier was proposed, which consists of diatomite, iron hydroxide sol (III) and silica sol. Application of the diatomite with nanoscale layer of nanomodifier allows getting a stone mastic asphalt, which has high values of physical and mechanical properties and allows refusing from expensive stabilizing additive. Mineral filler was replaced by diatomite, which has been modified by iron hydroxide sol (III) and silica sol. Modified diatomite allows sorption of bitumen and increase the cohesive strength and resistance to shear at positive temperatures. The modified asphalt has higher resistance to rutting at high temperature, abrasion resistance at low temperature and impact of climatic factors: alternate freezing and thawing, wetting-drying, UV and IR radiations. It is achieved by formation of solid and dense bitumen film at the phase interface and controlling the content of light fractions of the bitumen. The modifier consists of sol of iron hydroxide, which blocks the oxidation and polymerization of bitumen during operation. The proposed material allows controlling the initial structure formation of stone mastic asphalt. It was shown that modern test methods allow assessing the durability of asphalt in the design phase compositions.
DOI: 10.22227/1997-0935.2015.3.29-39
Pages 40-47
Great water losses in the internal plumbing of a building lead to the waste of money for a fence, purification and supply of water volumes in excess. This does not support the concept of water conservation and resource saving lying today in the basis of any building’s construction having plumbing. Leakage means unplanned of water losses systems in domestic water supply systems (hot or cold) as a result of impaired integrity, complicating the operation of a system and leading to high costs of repair and equipment restoration. A large number of leaks occur in old buildings, where the regulatory service life of pipelines has come to an end, and the scheduled repair for some reason has not been conducted. Steel pipelines are used in the systems without any protection from corrosion and they get out of order. Leakages in new houses are also not uncommon. They usually occur as a result of low-quality adjustment of the system by workers. It also important to note the absence of certain skills of plumbers, who don’t conduct the inspections of in-house systems in time. Sometimes also the residents themselves forget to keep their pipeline systems and water fittings in their apartment in good condition. Plumbers are not systematically invited for preventive examinations to detect possible leaks in the domestic plumbing. The amount of unproductive losses increases while simultaneous use of valve tenants, and at the increase of the number of residents in the building. Water leaks in the system depend on the amount of water system piping damages, and damages of other elements, for example, water valves, connections, etc. The pressure in the leak area also plays an important role.
DOI: 10.22227/1997-0935.2015.3.40-47
Pages 48-58
The purpose of this paper is to design rationale for the use of protective pads of geotextiles and geomembranes permeability of PD using these pads. In order to justify the use of protective pads made of geotextile for reducing the defectiveness geomembrane soil fractions, the existing formulas to determine the thickness of the film element of impervious devices were examined. The calculations according to the formulas show that HDPE geomembrane with a minimum thickness of 1,0 mm, the protective lining of the geotextile should be applied at the average diameter fractions of soil of more than 6,5 mm, and for geomembranes HDPE - at a diameter of soil fractions of over 15,5 mm. In order to estimate the permeability of the TFG geomembrane using additional protective linings of geotextile in the scientific article the basic design schemes of such coatings with one and two layers of protective linings of geotextiles were considered. The evaluation results of water permeability of impervious surfaces with geotextile and for comparison - without geotextiles are given in a table. As it is shown by the data presented for the design scheme with a single layer of geotextile geomembrane at the base (in the presence of small holes in the geomembrane) the decrease the effectiveness of an anti-covering is more than 268,0 %, and for the settlement scheme covering with two layers of geotextile there will be a very large reduction in the efficiency, which almost completely reduces the effectiveness of the coating to the value of the geomembrane permeability of a soil layer without geomembrane with the filtration flow rate of 71,75 m
3/day, against water permeability of the geomembrane cover - 38,52 m
3/day. From the foregoing, it can be concluded that the application of a coating design of well filtering gaskets made of geotextile is justified in terms of protecting the geomembrane from mechanical damage, but greatly reduces the effectiveness of impervious cover in case of its damage.
DOI: 10.22227/1997-0935.2015.3.48-58
Pages 59-68
Mathematical hydrogeology model of the territory of Kowsar Project was created with account for the results of the engineering surveys and hydro geological monitoring, which was conducted in the process of Kowsar Project construction. In order to create the model in the present work a universal computer system Ansys was used, which implements the finite element method and solid modeling technology, allowing to solve the filtration problem with the use of thermal analogy. The three-dimensional geometric model was built with use of the principle “hard body” modeling, which displays the main line of the territory relief, including the created water reservoir, geological structure (anticline Duk) and the main lithological complexes developed within the territory. In the limestone mass As here is a zone characterized by water permeability on territory of Kowsar Project, and a layer characterized by seepage feeding, which occurs outside the considered territory. The water reservoir is a source of the change of hydro geological situation. The results of field observations witness, that the levels of underground waters within the area of the main structures reacts almost instantly on the water level change in the water reservoir; the delay period of levels change is not more than 1,5…2,0 weeks at maximum distance from the water reservoir. These particularities of the hydro geological regime allow using the steady-state scheme of the decision of forecast problems. The mass of limestone As, containing the structures of the Kowsar Project, is not homogeneous and anisotropy in its seepage characteristics. The heterogeneity is conditioned by exogenous influence on the mass up to the depth of 100…150 m. The seepage anisotropy of the mass is expressed by the difference of water permeability of the mass along and across the layers for almost one order. The structures of Kowsar Project is presented by a dam, grouting curtain on axis of the dam and consolidation curtain in its both banks, drainage structures. Underground waters of the territory are formed by infiltration. They unload in river Heirabad. In accordance with this circumstance, the northwest (the right bank) and the south-east (the left bank) hydro geological borders of the model are the borders with constant discharge seepage, entering from the area of the feeding in the area of unloading. The borders are distanced from the river on 2,5 km. In accordance with the regional direction of the flow of underground waters, the model is limited along the lines of the current (the impervious borders) at northeast (upwards on river) and south-west (down on river). Those borders are distanced from river on 2,2…2,3 km. As a result, the area of model is 28 km
2. Aroofing of almost watertight marls of the retinue Pb is the bottom border of the model. Theinternal borders are presented by the river Heirabad, the water reservoir and the drainage structures. The calibration of the model was conducted at the reservoir water mark of 580 m and 606…610 m. The correctness criterion of the decision had shown the convergence of the obtained values of discharge level of underground waters with the data of natural observations. In the process of calibration the revision of the input data was carried out - a seepage characteristic of thick limestone mass As and discharge, entering from the right and left bank borders of the model. The forecast calculation was performed for water reservoir level of 620 m. The creation of water reservoir has influenced the seepage regime of the territory by the area of more than 25 km
2. As a result of the buttress of the natural inflow there occurred the redistribution of the natural inflow and change of the direction of the natural inflow that has caused the appearance of springs in downstream of dam near the contact of the series As-Gs. The design inflow of underground waters in the river Heirabad on the area from dam up to the contact of the suites As and Gs in downstream is 2,4…2,6 m
3/s including springs. The share of the direct seepage from water reservoir forms ~40 % of this values, the rest 60 % correspond to the unload natural inflow redistributed as a result of buttress. It is possible to define the level and discharges of underground waters on the territory of hydro unit under any elevation of water reservoir with the help of the created geo seepage model. The model can be used for effectiveness evaluation of the grouting curtain in the operation period.
DOI: 10.22227/1997-0935.2015.3.59-68
Pages 69-78
The author considered the results of the numerical studies of stress-strain state of a 100 m high rockfill dam with a reinforced concrete face. In the analysis, the dam construction sequence and loads applied to it were considered; it was assumed that the reinforced concrete face was constructed after filling the dam. The calculations were carried out in the elastic formulation at various moduli of deformation and Poisson’s ratio. It was revealed that at rockfill settlement under the action of hydrostatic pressure the reinforced concrete face not only bends but also is subject to longitudinal force. The development of these forces is connected not only with rockfill shear deformation in horizontal direction. Depending on the value of rockfill Poisson’s ratio these longitudinal forces may be both compressive and tensile. At the Poisson’s ratio exceeding 0.25 the longitudinal forces are tensile, and when it is equal to 0.2 - they are compressive. Evidently these particular longitudinal forces are the course of crack formation in reinforced concrete faces of a number of constructed dams. The indirect confirmation of the development of tensile forces on the face is the fact that actually in all the dams with reinforced concrete face opening of perimeter joint was observed. Thus, in order to provide the strength of reinforced concrete it is important to increase rockfill shear modulus. Only the decrease of stone compressibility (i.e. increase of linear deformation modulus E) will slightly improve the stress state of the face, as the value of E has less effect on settlements and shear of the dam than Poisson’s ratio. High rockfill dams with reinforced concrete face may have a favorable stress state only at narrow site when the face horizontal displacements are inconsiderable and due to the settlements of rockfill in the face the forces are compressive but not tensile longitudinal forces.
DOI: 10.22227/1997-0935.2015.3.69-78
Pages 79-91
The most possible increase of market value after large-scale reconstruction can be reached when a building or a group of buildings are situated in rather economically attractive areas, while the most part of the area is already repaired. In these cases the costs of repairs can be compensated by means of increase in the market value and sale of additional floors. The wide use of more effective methods of construction can also increase the price in the repaired real estate objects. The influence on the economic value of houses and buildings can be considerable also due to the improvement of operational qualities and because of an esthetic component. The opportunities for substantial increase of energy efficiency in economic sense are directly connected with the needs for large-scale reconstruction of the outdated building. Nevertheless, the changes of just windows, repair of facades, etc. lead to reasonable improvement of power efficiency, and respectively and building costs in general. The use of natural resources in construction during repairs of the building and at the stage of operation influences the environment. The influence degree depends not only on isolation, but also on the choice of the type of repair, energy efficiency, front and roofing materials, and also on the use of energy raw materials, necessary for construction process.
DOI: 10.22227/1997-0935.2015.3.79-91
Pages 92-98
This research study defines the right of the customer to carry out public procurement for design objects of capital construction in the form of open competition, offers the comparative analysis of the evaluation criteria based on the old and the new legislative framework for public procurement. It was assumed, there in the legislation is no clear conceptual framework governing the selection of the evaluation criteria, the same as a method for improving the selection criteria for the assessment of the State order for the design. The process of public procurement in the Russian Federation beginning from 01.01.2014 g. is regulated by the federal law no. 44-FZ from 05.04.2013 “On the contract system in the procurement of goods, works and services for public and municipal needs” (hereinafter - the Law of the contract system). Open competition remains the most carefully prepared and developed of all the procedures for procurement. However, in practice the customers continued to violate the normative and legal regulation of public procurement. One of the most troublesome aspects of the Russian legislation is the criteria defined by customers to evaluate the participants who submitted their applications for the contest. Here we would like to note that according to the Law on contract system such criteria as “term of work performance” and “term and volume of providing the guarantee for quality of the works” aren’t subject to an assessment, in comparison with the Law on government procurements existing earlier. However, as scientific researches in the field show, these criteria were very essential and necessary for assessing the applications. The analysis of the past competitions showed that with the criterion “quality of works” the customer, in most cases, doesn’t establish any certain requirements to the participant of purchase. He asks to supply only the so-called offer on quality of works consisting in the detailed description of their performance according to the specification on design of the capital construction project, which is an integral part of competitive documentation on purchase execution. With such criteria as “qualification of the participant of competition”, “experience in similar types of works”, “business reputation” and “existence of purchase of the material and other resources necessary for work performance”, with adoption of law on contract system, serious changes didn’t happen. The innovation of the legislation is only that now the customer has to establish minimum / extremely minimum and/or maximum / extremely maximum assessment value according to these criteria in competitive documentation. The assessment of applications will occur in this case according to legislatively certain mathematical formulas of calculation. On the basis of the above, considering a scientific component of this research, it is possible to tell that, despite some changes of an assessment criteria, in general the mechanism of their choice hasn’t been improved.
DOI: 10.22227/1997-0935.2015.3.92-98
Pages 99-107
In the part 1 of the article 48.1 of the town planning code of the Russian Federation we can find a list of objects that are especially dangerous. Article 2 paragraph 59 of the contract system establishes the responsibility of the customer to conduct electronic auction, provided that the purchase of goods, works, services is included in the list established by the Government of the Russian Federation, or in an additional list approved by the highest body of the Executive power of the subject of the Russian Federation. By order of the Government of the Russian Federation dated 31.10.2013 no. 2019-r there was approved a list of goods and services, in case of procurement of which the customer is obligated to conduct an auction in electronic form. The list included "Building works", related to the code 45 (excluding code 45.12) according to the all-Russian classifier of products by economic activity (OKPD) OK 034-2007. The exception is the construction, reconstruction, overhaul of high-risk, technically complex objects of capital construction, provided that the cost of the purchase contract for the State needs is more than 150 million rubles; to provide municipal - 50 million rubles. Thus, the customer is obliged to conduct electronic auction in the case of procurement of construction works (code 45 OKPD OK 034-20071), besides the works relating to the code of 45.12 (drilling), if the initial (maximal) cost of purchase for State needs does not exeed 150 million rubles, for municipal needs - 50 million rubles. Here is an example. In St. Petersburg, three competitions were announced by the customer on the site for the construction of four underground stations with total value of 940 million rubles. How to place an order-public audition with limited participation? The results of the audit conducted by the OFAS around St. Petersburg, led to the cancellation of the tender. In particular, due to an incorrect choice of customer ways to purchase. According to the FAS, the subject of the procurement is to prepare the area for the construction of the underground, and not the construction as such.
DOI: 10.22227/1997-0935.2015.3.99-107
Pages 108-118
The paper presents a critical analysis of the major deficiencies in the presentation of the topic “redox reaction” in a modern high school chemistry course. The authors propose new methodological approaches to teaching of this subject. When generating the redox equations by electron-ion balance it is preferable to take the change in the oxidation as the basis, but not the balance of ion charge. The circuit of any redox reaction, if it takes place in a solution and can assume the formation of more than one strong electrolyte with different ions combinations, the products cannot be specified in molecular form. The equations of redox reactions, in which there are two reducing agent (or two oxidizer), which represent different substances, or as a result of which two products of oxidation or reduction are formed, are incorrect, as they reflect the parallel reactions.
DOI: 10.22227/1997-0935.2015.3.108-118
Pages 119-137
The author focuses on the analysis problems of the main metrics of scientific productivity for the faculty in the USA universities specializing in the investigations and teaching in the field of urban planning. The increasing role of the Internet is highlighted in the process of communicating the ideas of planning scientists to the professionals and public, extending the reach of academic communications and possibilities of estimating the quality of the investigations and impact. Using case study the methods of applying webometrics for citation analysis in the Internet are investigated. The analysis focused on the main criteria: productivity, visibility, reputation, and impact. The article proposes an expanded approach for estimating general scientific popularity and impact of academics in the Internet, which includes publication analysis in frames of “gray literature”, teaching and outreach activity, which may also be a significant part of the scientific activity. The author stated the importance of academic visibility estimation both for promotion, improving competitiveness of a faculty member on the labor market in the sphere of educational services, and for urban planning schools’ development in general, raising their reputation, prestige and impact, getting the opportunities for financed researches, consolidating the positions on the global educational and science market.
DOI: 10.22227/1997-0935.2015.3.119-137