Calculation and Design of Building Structures Given the Variatropy of the Structure, Sections and Differentiation of Constructive Characteristics of the Materials

Author(s):  
Л. Р. Маилян ◽  
С. А. Стельмах ◽  
Е. М. Щербань

Состояние проблемы. Возрастающие объемы строительства требуют новых технологических, конструктивных и расчетных решений железобетонных элементов. Центрифугирование, являясь перспективной технологией производства, приводит к вариатропным, т. е. различающимся по своим характеристикам (плотности, прочности, деформативности и др.), по сечению бетонам и конструкциям, выполненным из них. Это во многих случаях необходимо учитывать в расчете и проектировании, однако исследований касательно этой темы практически не проводилось. Поэтому при расчете и проектировании строительных конструкций вариатропной структуры обычно закладывается необоснованно большой запас прочности, что приводит к их сильному удорожанию. В нормах проектирования и научной литературе отсутствуют теоретические и практические методы расчета центрифугированных железобетонных строительных конструкций с учетом вариатропности структуры и характеристик бетона по сечению. Отдельными данными подтверждена эффективность центрифугирования, но в полной мере использовать его преимущества из-за отсутствия в существующих методах расчета учета вариатропности структуры пока невозможно. Результаты и выводы. В результате обзора и анализа определены векторы развития и направления будущих исследований, заключающиеся в изучении работы сталежелезобетонных центрифугированных и виброцентрифугированных сжатых элементов с использованием фиброармирующих волокон. Предполагается совершенствовать технологию изготовления и методики расчета для еще полного и всестороннего исследования такого уникального явления, как вариатропия структуры бетона строительных конструкций. Statement of the problem. Increasing numbers of construction call for new technological, structural and design solutions for reinforced concrete elements. Being a promising production technology, centrifugation causes variatropic characteristics, i. e., differing ones (density, strength, deformability, etc.), in cross section of concrete and structures made of them. This is oftentimes essential to consider in both calculation and design, but research on this topic is literally non-existent. Thus while calculating and designing building structures of the variatropic structure, an unreasonably large margin of safety is commonly present leading a surge in their price. In design guidelines and scientific literature there are no theoretical and practical methods of calculation of centrifuged reinforced concrete building structures considering the variability of the structure and characteristics of concrete in cross section. Some data confirm the efficiency of centrifugation, but it is not yet possible to make complete use of its advantages due to the lack of existing methods for calculating the variability of the structure. Results and conclusions. Based on the review and analysis, the vectors of development and directions of future research are identified, which are to sinvestigate the operation of reinforced concrete centrifuged and vibrocentrifuged compressed elements using fiber reinforcing fibers. It is suggested that the manufacturing technology and calculation methods are improved for a more complete and comprehensive study of such a unique phenomenon as variatropy of the concrete structure of building structures.

Author(s):  
L. R. Mailyan ◽  
S. A. Stel'makh ◽  
E. M. Shcherban'

Statement of the problem. The increasing volumes of construction require new technological, structural and design solutions for reinforced concrete elements. Centrifugation, being a promising production technology, leads to variatropic - differing in their characteristics (density, strength, deformability, etc.) in the section of concretes and structures made of them. In many cases, this must be taken into account in the calculation and design, but such studies have practically not been carried out. Therefore, when calculating and designing building structures of a variatropic structure, an unreasonably large margin of safety is usually laid, which leads to their strong rise in price. In the design standards and scientific literature, there are no theoretical and practical methods for calculating centrifuged reinforced concrete building structures, taking into account the variability of the structure and characteristics of concrete over the section. Separate data have confirmed the efficiency of centrifugation, but it is not yet possible to fully use its advantages due to the lack of accounting for structure variability in existing calculation methods. Results and conclusions. As a result of the review and analysis, the vectors of development and directions of future research have been identified, which consist in studying the work of steel-reinforced concrete centrifuged and vibro-centrifuged compressed elements using fiber-reinforcing fibers. It is proposed to improve the manufacturing technology and calculation methods for a complete and comprehensive study of such an undoubtedly interesting and unique phenomenon as the variatropy of the structure of concrete of building structures.


1997 ◽  
Vol 1 (3) ◽  
pp. 90-115 ◽  
Author(s):  
Yasuhisa Sonobe ◽  
Hiroshi Fukuyama ◽  
Tadashi Okamoto ◽  
Nagahide Kani ◽  
Kouzou Kimura ◽  
...  

Author(s):  
Л. Р. Маилян ◽  
С. А. Стельмах ◽  
Е. М. Щербань ◽  
М. П. Нажуев

Состояние проблемы. Железобетонные элементы изготавливаются, как правило, по трем основным технологиям - вибрированием, центрифугированием и виброцентрифугированием. Однако все основные расчетные зависимости для определения их несущей способности выведены, исходя из основного постулата - постоянства и равенства характеристик бетона по сечению, что реализуется лишь в вибрированных колоннах. Результаты. В рамках диаграммного подхода предложены итерационный, приближенный и упрощенный способы расчета несущей способности железобетонных вибрированных, центрифугированных и виброцентрифугированных колонн. Выводы. Расчет по диаграммному подходу показал существенно более подходящую сходимость с опытными данными, чем расчет по методике норм, а также дал лучшие результаты при использовании дифференциальных характеристик бетона, чем при использовании интегральных и, тем более, нормативных характеристик бетона. Statement of the problem. Reinforced concrete elements are typically manufactured according to three basic technologies - vibration, centrifugation and vibrocentrifugation. However, all the basic calculated dependencies for determining their bearing capacity were derived using the main postulate, i.e., the constancy and equality of the characteristics of concrete over the cross section, which is implemented only in vibrated columns. Results. Within the framework of the diagrammatic approach, iterative, approximate and simplified methods of calculating the bearing capacity of reinforced concrete vibrated, centrifuged and vibrocentrifuged columns are proposed. Conclusions. The calculation according to the diagrammatic approach showed a significantly better convergence with the experimental data than that using the method of norms, and also performs better when using differential characteristics of concrete than when employing integral and particularly standard characteristics of concrete.


2020 ◽  
Vol 315 ◽  
pp. 07004
Author(s):  
Dmitry Mailyan ◽  
Alik Blyagoz ◽  
Konstantin Kretinin

The paper contains the issues related to the creation of a non-uniform prestress cross-section of reinforced concrete elements compressed during operation of working with a one-way eccentricity of the resultant longitudinal forces.


Author(s):  
I Ketut Nudja S ◽  
I N. Sutarja ◽  
Mayun Nadiasa

The cost of the project itself , in line with the accounting system which consists of direct costs and indirect costs . Contractor in determining competitive bidding strategy, should propose a cost which include estimate real cost plus mark up . Based on observations at PT. Sarana Bangun Ragam Cipta, a contractor company , found that the company does not  follow the rules mentioned above, Besides that the book keeping system for the project cost has not implemented a financial accounting system properly , so that the  proportion of direct costs and indirect costs of each project is un know. It required a study to be conducted to  determine the proportion of direct costs to indirect costs and indirect cost model. Quantitative research was conducted on the 12 (twelve ) project of  reinforced concrete building structures using two (2 ) independent variables , namely the direct costs ( X1 ) and duration ( X2 ) and 1 ( one ) dependent variable , ie indirect costs (? ) . Descriptive analysis to determine the proportion of indirect costs to direct costs . Analysis of data using multiple linear regression analysis to determine the indirect cost model of reinforced concrete building structures projects. From analysis found the average proportion of indirect costs to direct cost was 8.50 % , meanwhile  indirect cost model is ? = - 1.462E7 + 0.056 ( X1 ) + 558,775.937 ( X2 ) , where : ? = Indirect costs ( Rp . ) , X1 = direct costs (Rp .) , X2 = Duration ( days ) . The proportion of indirect costs can be used to calculate indirect costs = 0.085 x direct costs and the above model can also be used to predict the value of ? with accuracy 90% or at ? (±) 0.10, if the values ??of X1 and X2 is know on popolation where the data is taken


2012 ◽  
Vol 195-196 ◽  
pp. 297-302 ◽  
Author(s):  
Wei Feng Zhao ◽  
Jing Zhou ◽  
Guo Bin Bu

Bamboo is mainly a tropical and subtropical plant which is found adequate in many countries. The strength of bamboo as concrete reinforcement is much lower than steel bar reinforcement. However, one of the merits is a cheap and replenishable agricultural resource and abundantly available. Due to excellent properties like high strength to weight ratio, high tensile strength and free-cutting and processing, bamboo as a potential reinforcement material in place of steel is widely available in concrete structural elements. The present paper introduces some of the existing studies and application technology of bamboo reinforced concrete elements in building structures, such as bamboo reinforced concrete columns, beams, slabs and walls.


Sign in / Sign up

Export Citation Format

Share Document