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заинтересованным службам и руководителям. Это даст возможность оперативно вести контроль за ходом выполнения программы выпуска.
Главная задача оперативного планирования состоит в обеспечении на предприятии слаженного и ритмичного хода всех производственных процессов. На основе более полного представления нормативной базы возможно расширение расчетов: трудоемкость производственной программы, потребность материала и комплектующих, потребность в производственных рабочих. Это позволит достичь более полной автоматизации производства.
Список использованной литературы
1. Бухалков М.И. Планирование на предприятии, - учебник М.: 2009.
2. Винокур Л.Б., Осипов В.А. Организация производства и менеджмент, учебно-методический комплекс, ДВФУ, 2015.
© Лещукова И.В., 2016
UDC 624.071
Mavlonov Ravshanbek Abdujabborovich, Nosirjonov Nodirbek Ravshanbek ugli
Teacher and student of department of "Construction of buildings and structures"
Namangan Engineering Pedagogical Institute, Namangan city, Uzbekistan ravshanbek.mavlonov@gmail.com
DEVELOPMENT AND APPLICATION OF ULTRA HIGH PERFORMANCE CONCRETE
Annotation
Ultra High Performance Concrete (UHPC) with a high compressive strength of up to 300 MPa and an improved durability marks a quantum leap in concrete technology. This high performance material offers a variety of interesting applications. It allows the construction of sustainable and economic buildings with an extraordinary slim design. Its high strength and ductility makes it the ultimate building material e.g. for bridge decks, storage halls, thin-wall shell structures and highly loaded columns.
Key words
Ultra High Performance Concrete, compressive strength, steel fiber, high strength concrete, coarse aggregate, long
term stability
Within the last two decades amazing progress has been made in concrete technology. One of the breakthroughs is the development of ultra-high-performance concrete with a steel like compressive strength of up to 300 MPa and a remarkable increase in durability compared even with high-performance concrete. In combination with a sufficiently high amount of steel fibers it is now possible to design sustainable filigree, lightweight concrete constructions without any additional reinforcement. In prestressed construction elements the prestressing forces may be increased significantly especially if high-strength steel is used. Long span girders, bridges and shells are ideal applications widening the range of concrete applications by far. First practical steps into the future of concrete constructions have already been done.
In the mid 60's, concrete with strength ranging from 40 to 80 MPa, named high performance concrete (HPC). It is first use in significant quantities in major structures in Chicago, USA. As the development has continued, the definition of high-strength concrete has changed. In the 1950s, concrete with a compressive strength of 34 MPa was considered high strength. In the 1960s, concretes with 41 and 52 MP a compressive strength were used commercially and in the early 1970s, 62 MPa concrete was being produced and introduced in many applications such as high-rise
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buildings and long-span prestressed concrete bridges. More recently, compressive strengths concrete over 150 MPa have been known as Ultra High Performance Concrete (UHPC) which improves the advantages of HPC and present a great interest for casting concrete industry by using these new materials. So, it is possible to produce lighter products with thinner sections and open up new possibilities for bridge and high -rise building and offer economic advantages through savings in reinforcing steel and cross sectional dimensions, this leads to lower dead weight, thus allowing large spans.
UHPC is a new class of concrete technology. When compared with HPC, UHPC tends to exhibit superior properties such as advanced strength, durability, and long-term stability.
UHPC are made using fine aggregates, very low amounts of water and high amounts of cement. These materials are characterized by a dense microstructure. The sufficient workability is obtained by using superplastisizers in combination with the low-water demand of the fresh concrete.
From the strength point of view, the classification of concrete strength may be made as follows:
1) Normal Strength Concrete (NSC) up to B60 MPa
2) High Strength Concrete (HSC) B60 to B100 MPa
3) Very High Performance Concrete (VHPC) B100 to B150 MPa
4) Ultra High Performance Concrete (UHPC) B150 to B300 MPa
The main advantage that UHPC has over standard concrete is its high compressive strength. Other advantages include low porosity, improved microstructure and homogeneity, high flexibility with the addition of fibers. As a result of its superior performance, UHPC has found application in the storage of nuclear waste, bridges, roofs, piers, seismic-resistant structures and structures designed to resist impact loading. Owing to its high compression resistance, precast structural elements can be fabricated in slender form to enhance aesthetics. Durability issues of traditional concrete have been acknowledged for many years and significant funds have been necessary to repair aging infrastructure. UHPC possesses good durability properties and lower porosity and capillaries account for its endurance. UHPC construction requires lower maintenance costs in its service life than conventional concrete. UHPC may incorporate larger quantities of steel or synthetic fibers and has enhanced ductility, high temperature performance and improved impact resistance. This enables structural members to be built entirely from fiber reinforced UHPC without the use of conventional transverse reinforcement, relying on the UHPC without traditional reinforcement because of its advantageous flexural strength.
Fig.1 summarizes the typical compositions of concrete materials at different levels of performance. While ordinary and high performance concrete consist of cement, fine and coarse aggregates, and admixtures, UHPC is made up of cement, fine aggregates, admixtures, steel fibers, and nano-fillers. The coarse aggregate was replaced in UPHC with steel fibers and nano-fillers that enhance the mechanical strength of UHPC. The nano-filler increased not only compressive strength but also tensile strength.
Fig. 1 - Composition of concrete materials at different levels of performance
One of the most advanced cementitious composites is the reactive powder concrete (RPC), belonging to a group of UHPC. This material is often classified as so called low-temperature ceramics. The production of such composites has been made possible, first and foremost, thanks to the progress in mineral binder technology, increased
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availability of highly effective superplasticizers and wide recognition of influence of mineral additives on the microstructure and general properties of cementitious composites. The compressive strength of this multi-component material ranges from 150 to 300 MPa, depending on the composition and curing conditions. Its place in a series of cement-based composites is illustrated by the following diagram (Fig. 2).
Fig. 2 - Generalized curve of concrete development
References:
1. Ризаев Б.Ш., Мавлонов Р.А., Мартазаев А.Ш.. Физико-механические свойства бетона в условиях сухого жаркого климата // «Инновационная наука» - 2016. - №7/2015 - С. 55-58. г. Уфа, Россия.
2. Абдурахмонов С.Э., Мавлонов Р.А. Трещины в железобетонных изделиях при изготовлении их в нестационарном климате. // Материалы сборника международной НПК «Наука и образование: проблемы и перспективы». 13 март 2014 г. - С. 197-198. г Уфа, Россия.
© Mavlonov R.A., Nosirjonov N.R., 2016
УДК 624.012
А.Ш. Мартазаев асс. ОД. Фозилов асс. Н.Р.Носиржонов
Наманганский инженерно-педагогический институт, Узбекистан.
ЗНАЧЕНИЕ РАСЧЕТОВ СТАТИЧЕСКОГО И ДИНАМИЧЕСКОГО ВОЗДЕЙСТВИЯ
НАЗЕМЛЯНЫЕ ПЛОТИНЫ.
Аннотация
В статье указывается на актуальность расчета статического и динамического воздействия на земляные плотины. Приводится заключение полученных результатом расчета положения статического напряжения земляных плотин методом конечных элементов.
Ключевые слова:
Грунт, динамика, статика, давление, сооружение, землетрясение, напряжение, гидротехнический, гидроэластичный, плотина, гидродинамика, гидростатика, конечный элемент.
