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complete loss of stability of all reinforcing panels is observed, and in the basic shell there occur some local losses of stability in the form of wall bulging-out in certain lengths approximately equal to the distances between the reinforcing panels. Here local losses of stability of the wall of the basic shell are more pronounced and greater in size than in the models reinforced by cylindrical panels and rolled channel bars.
Similar pattern of stress-strain state is observed in Z-axis. Maximum and minimum normal stresses of tension and compression are located in the wall of the reservoir and reinforcing panels.
8. Maximum and minimum tangent stresses of tension and compression are located in the wall of the reservoir and reinforcing panels. A complete loss of stability of all reinforcing panels is observed, and some local losses of stability in the form ofwall bulging-out occur in the basic shell.
9. Taking into account the feasibility of manufacturing conditions, the "in-function" cost, it is recommended to use the reinforcing elements in the form of cylindrical panels.
References:
1. Kaplun A. B., Morozov E. M., Olfer'eva M. A. ANSYS in Engineer Hands. A Practical Guide. - Moscow: Nauka, - 2003. - 134 p.
2. Building Code - 2.03.05-97. «Steel structures. Design Standards». Tashkent, - 1997. - 117 p.
DOI: http://dx.doi.org/10.20534/ESR-16-9.10-184-186
Erboyev Shavkat Ochiltoshevich, Jizzakhpolytechnic institute, Senior teacher, E-mail: [email protected]
Organizational and structural measures to improve the process of operation concrete span
Abstract: Ways of improving the structures of exploitation and practical ways of assessment of technical condition of the operated railway flying structures of bridges.
Keywords: bridge constructions, ferroconcrete, flying structures.
Analyzing the present situation of the bridge maintenance, it can be concluded that the Republican roads of JSC "Uzbekistan Railways" ("Uzbekiston Temir Yullari") absolutely don't meet the requirements of a durable and reliable operating structure. Service regular examinations and tests are not well organized and therefore Republican railway does not have a full picture of the technical condition and capacity of operated facilities.
Preservation and maintenance of normalized reliability of the operated bridges — standing problem, requiring for their solution wide variety of organizational activities.
In developing these measures should take into account that exploited the bridges built at different times for different regulations and loads and are in varying condition. Therefore, the collecting and study of the history of operation and organization of repair requires a systematic approach.
The observed reduction of operational reliability of bridge spans, in most cases, should be attributed to poor organization of work operations. However, as mentioned in [1] in the bulk of the work of these units includes repairs to the regulatory structures under overhead bed, track structure on bridges and other works, and repair of the superstructures practical is not given any attention.
Renovations to improve the reliability of a bridge span upon the occurrence of a failure on the basis of endurance of the concrete, require a large amount of restoration work [1], which forces the linear enterprises of the railroads impossible to master. Specialized units of the JSC "Uzbekistan Railways", (Bridge building) where there is a strong mechanized equipment and machines, are not engaged in repair. As a result of solving many of the issues are time consuming, creating every year the danger of injuries, further development of which will restrict load capacity and premature structure failure.
It is unacceptable that many bridge organizations have the distraction of work, not associated with the repair of engineering structures. So, in General, JSC "Uzbekistan Railways" extraneous
load is 22% of the total. Despite the fact that annual allocations for capital repairs of bridges increased at an average rate of 7-8%, the situation does not change.
The way out is only possible with the creation of specialized mechanized units in ATIE (Association of track industry enterprises), organized by the Association of the track in the light of decisions on restructuring of work of railway transport. This does not require increase in staff, and the only restructuring of the production units. The existing small team in the production areas (in track) are combined into one unit headed by the Deputy chief ATIE on artificial structures. Created unit when equipping it with the necessary equipment to perform all repairs, including reinforcement of individual elements of the superstructure and replace them. This creates a separate, centralized, mechanized and industrial mobile base of operation. This allows you to increase the profitability of the repair of bridges [2].
In connection with the establishment of such enterprises should rebuild work bridge test stations at JSC "Uzbekistan Railways". It is necessary to strengthen the link of their created units of the repair of bridges. The estimated structural organization of service operation is given in figure 1.
Part of a bridge-test station to a collection of information about the state operated bridges and control to streamline technical documentation management, headed by a qualified engineer, bridge-builders and technology. The task group is to prepare information on the status ofbridges, identification of the need for test structures with defects and damages.
Inspection and testing of bridges produces a bridge-test station. Along with the traditional examinations and tests depends on the parameters for determining the residual life.
To obtain the most complete picture of the stress strain state of the exploited superstructures appropriate ordering of the data. In the future, these data can be processed and analyzed by computer.
Organizational and structural measures to improve the process of operation concrete span
Figure 1. Proposed structure of service operation
The main objective definition of technical condition of the operated flying structures and constant observation of change of their key parameters.
In work the attempt to develop almost convenient for practice of a way behind observation of the general a condition of flying structures is made. At the same time for basic it is taken a technique [4; 5], applied earlier to assessment of bridge systems which allows to establish at the same time the level of the current maintenance of bridges and to determine by the mark scheme of their general technical condition.
All defects and damages, in the operated reinforced concrete flying structures, found as a result of their long-term inspections are broken into three categories and the mark assessment is appropriated to each category:
Table 1. - Characteristic of defects of
0 category — defects are absent or available insignificant defects do not influence the general technical condition of flying structures — perfectly (5);
1 category — defects worsen service conditions, do not influence loading capacity, but reduce durability — well (4);
2 category — the available defects need to be eliminated in due time as their further development can lead to restriction of the admission of trains — satisfactory (3);
3 category — loading capacity flying a structure are less than external loading, defects threaten traffic safety of trains — unsatisfactorily (2).
The category of defects is established as a result of technical diagnostics. As a matter of experience operation of flying structures all defects are systematized and mark estimates are appropriated to each of them and these data are entered in table 1. reinforced concrete flying structures
Category defects Mark estimates on each defect Description of defects
1 2 3
0 Defects are absent 0,02
Superficial shrinkable cracks to 0,2 mm 0,02
Insignificant prick out concrete up to 0,5 cm in depth 0,02
1 Leaching of concrete on a surface in flying structures 0,02
The damaged drainage tubes, chips and sinks in concrete without stripping of fittings 0,02
Begin to flow rusts because of the beginning of corrosion of fittings 0,02
Shrinkable cracks disclosure more than 0,2 mm 0,02
2 Cracks in a sidewalk part of consoles 0,1
Violation of a waterproofing of a ballast trough, begin to flow leaching of cement mortar from microcracks of a flying structure 0,1
Peeling of a protective layer, chips of concrete, sink 0,1
Corrosion (to 20% of the area) naked working fittings 0,1
Break of one core of working fittings 0,1
Longitudinal and cross cracks in consoles with solution 0,1 leaching 0,1
Destruction of concrete in a zone of hinges of folding consoles, begin to flow dirt, leaching of cement mortar from the hinge 0,1
Cross cracks disclosure more than 0,2 mm in preintense flying structures 0,1
The closed-up cracks changing under loading disclosure more than 1 mm 0,1
Destruction of concrete of sides, consoles of flying structures 0,1
Insufficient width of deformation seams 0,1
Building of boards of a ballast trough more than 20 cm 0,1
Absence or malfunction of dimensional gate 0,1
1 2 3
3 The destroyed protective layer with the bared rusted fittings (more 20%ploshchadi) 2,0
Break more than one core of working fittings 2,0
Inclination of folding consoles, cracks in a root of consoles 2,0
The cracks changing disclosure under loading 2,0
Availability cross more 0,2mm in preliminary and intense flying structures 2,0
The class of a flying structure is lower than a class of loading 2,0
The through cracks separating a carriageway plate from the main beam 2,0
On end technical diagnostics and establishments of total, the • good (4) — at 0,02 B 0,1 (inclusive);
appropriated mark estimates "" is accepted the following conditions: • satisfactory (3) — at 0,1 B 2,0
• excellent (5) — B = 0; • unsatisfactory (2) — 2,0 B
References:
1. Shestikov V. I. Ways of increase in durability of the operated bridges//Designing, repair and operation of artificial constructions on and/M.: TsBNTI, - 1996. - No 52. - P. 5-14.
2. V.P Chirkov. Theoretical bases of forecasting of service life of steel concrete designs. Tutorial. - M.: MIIT, - 1998. - P. 56.
3. Bondarenko V. M., Iosilevsky L. I., Chirkov V. P. Reliability of building structures and bridges. - M: Publishing house of Academy of architecture and construction sciences, - 1996. - P. 220.
4. A research ofwork of the bases and flying structures of bridges in extreme conditions ofEnvironments Asia on Bridge building objects. Tashkent-1988. - P. 115. No. 7 Report on NIR (interval) of DSP/TashIIT.
5. Mamajanov R. Probabilistic forecasting of a resource of steel concrete flying structures of bridges. - Tashkent: Fan. - 1993. - 156 p.
DOI: http://dx.doi.org/10.20534/ESR-16-9.10-186-188
Kurbanov Janibek Fayzullayevich, Department of «Electric communication and radio», Tashkent Institute of Railway Transport Engineers,
Tashkent, Uzbekistan E-mail: [email protected]
The control system of a single unit of the spatial field
Abstract: This paper deals with the development of control systems and the hardware of the device unified spatial field (DUSF), as well as identifying opportunities for its use of new functional materials. The control system provides an automatic feed control voltage and current, auto shut off circuit when the temperature rises in the coils.
Keywords: Frequency, thyristor, electric fields, magnetic fields, drivers, microcontroller, power management, transistors IGBT.
There are many methods and schemes of control technology grinding and extraction of bulk materials by means of a single unit of the spatial field. The easiest way to control — this control thyristors. Thyristors are the power devices of any technology of grinding and extraction. But most important in this technology is that the thyristors can be used at a low frequency of 2 Hz to 125 Hz. There thyristors frequency type PM, but they are designed to manage frequencies up to 10 kHz. For the grinding of minerals require very high currents of up to 300-450 A. The maximum current of thyristor frequency reaches 125 A — 250 A. It is therefore necessary to develop a universal management system that works with high currents and a wide frequency range from 2 Hz to 30 kHz. Therefore the choice of the theme of the article is relevant [1; 2-3].
The aim is to: the development of a universal management system that allows you to use it without an intermediary — thyristor converter. This system should possess a wide range of duty cycle adjustment is 5, 10, 20, 30, corresponding to frequencies of 5, 15, 18, and 25 Hz in the range of 3, 8, 17, 20, 25 kHz. Another disadvantage of the thyristor converter is that it is not included in the beginning of the line voltage half cycle and at arbitrary times which are separated from the half cycle beginning at a time not
exceeding the period of firing pulses, i. e. 50-100-200 microseconds. During this time the line voltage may increase to approximately 5-20 V. This results in a reduction of the input voltage. Another problem is that during the action of the trigger pulse current through the thyristor reaches the holding current, the thyristor is turned off after the end of the pulse. In developing the technology were used special methods based on the interaction of electric and magnetic fields and at different behavior of elements in the electric and magnetic fields. Particles with different electrical and magnetic properties become different trajectory. To manage these fields have developed special types of coil, an electromagnet and a copper rod. Block diagram of a single spatial field is shown in figure 1.
For grinding and extraction of bulk materials by means of a single unit of the spatial field, it requires a power supply of 220 V the voltage step-down transformer to reduce the voltage of 120/80V. It is necessary to obtain a sufficiently large circuit current 8 pulsed mode (up to 300A) at low supply voltage (up to 80 V) and low frequency (5 Hz to 30 kHz on). For this purpose it is necessary to choose the management and implementation of hardware for guaranteed power switching devices [2, 1-3].
