286 Works

Scheduling workflows for scattered objects

Yuri Kalugin & Roman Romanov
As a rule, the task of optimal scheduling, including reducing the total duration of the project occurs when developing and adjusting schedules. The essence of flow shop scheduling problem on the scattered objects with the use methods and models calendar planning was presented. The branch and boundary method were proposed as an exact method for determining the optimal permutation including the scheme of branching and rules for determining the lower boundaries. Heuristic algorithms for determining...

Strength evaluation of the Prussian vaults made from brick aggregate concrete

Romuald Orlovich, Rafal Nowak, Nikolai Vatin & Vladimir Bespalov
The behavior of Prussian vaults of brick aggregate concrete differs both from the behavior of brick vaults and classical flat slabs. Such vaults are particularly susceptible to physical damage and deterioration. To determine the real bearing capacity of the vaults, the authors not only performed the in-situ determination on several sections with deflection control, but also numerical simulations of the multi-span system of Prussian vaults in the program complex Abaqus. Moreover, experimental comparisons between damaged...

Деформации периодической фермы с раскосной решеткой

Михаил Николаевич Кирсанов & Наталия Васильевна Заборская
Рассмотрена схема плоской статически определимой фермы решетчатого типа. Ферма имеет две опоры и загружена равномерной нагрузкой по нижнему или верхнему поясу. Найдены аналитические зависимости прогиба конструкции и смещения подвижной опоры от ее размеров, нагрузки и числа панелей. Показано, что если число панелей кратно трем, то ферма кинематически изменяема, что явствует из равенства нулю определителя системы уравнений равновесия. Найдена соответствующая схема возможных скоростей узлов. Для вывода результатов использована система компьютерной математики Maple и метод индукции, ранее...

Organizational and technological reliability of the construction process

Vadim Kabanov
Construction projects of buildings and structures, as well as plans of construction and installation works are often subjected to fair criticism from the Pro-producers of the work. Such criticism is that the calculated cost value and long lasting-STI CMP does not take into account the specificity of real contractors. To address these criticisms and proposals were developed for the assessment of such intensity values of SMR production, which most realistically take into account the actual...

Treatment of wastewater resulting from iron ore beneficiation

Tatyana Budykina
The overall objective of this article is to study the potential of the reagent treatment of wastewater resulting from the iron ore beneficiation process, as well as preventing the discharge of the wastewater into the open waters. The wastewater at the Mikhailovskii iron ore beneficiation plant (Kursk Region, Russia) discharged into a tailings pond has become an object of the research. This article looks at the sedimentation kinetics of the wastewater resulting from the wet...

Burnt rock of the coal deposits in the concrete products manufacturing

Mikhail Kuz'min, Leonid Larionov, Victor Kondratiev, Marina Kuz'mina, Vyacheslav Grigoriev & Alina Kuz'mina
The paper presents the results of the comprehensive study of the composition, properties and structure of the burnt rock found at the mining dumps of Cheremkhovo coal deposit (Irkutsk region, Russia). In the course of laboratory research, which included optical crystallography, there have been established the reasons accounting for the extent of burnt rock activity when in contact with cement during the cement stone formation. The benefit of the burnt rock as an active mineral...

Alkali-activated slag binders from rock-wool production wastes

Vladimir Erofeev, Alexander Rodin, Vladislav Yakunin, Andrej Bogatov, Viktor Bochkin & Aleksej Chegodajkin
The article exposes the results of studies on the production of alkali-activated slag binders from rock-wool production wastes and their composite derivatives, which are resistant to corrosive effects of biological environment. Thermal analysis showed that the structurization in the "rock wool production waste-water-NaOH" system is most efficient with the NaOH/waste ratio of 0.02–0.03, and the main newly-formed phases in the solidified alkali-activated slag composites are low-basic calcium hydrosilicates and analcime. The best values of the...

Granulated foam-glass ceramics for ground protection against freezing

Konstantin Ivanov
The problem of seasonal freezing and frost heaving of soils of the engineering structures foundations is considered. For the purpose of thermal protection of soils, a granular inorganic closed-porous material, named granulated foam-glass ceramic is proposed. In the laboratory modeling of seasonal freezing, the dynamics of temperature and deformation, as well as the distribution of moisture over the depth of the soil, were studied in three cases: a soil without thermal insulation, a soil with...

Silica fumes of different types for high-performance fine-grained concrete

Aleksandr Rassokhin, Andrey Ponomarev & Oleg Figovsky
One of the most often and successfully applied admix as a part of the modified concrete is active amorphous silica fume. The increased practical interest in this admix has led to emergence in the market of various producers and also to emergence of different types (brands) of the silica fume produced from various raw materials with use of various technologies. At the same time their makeup, dispersion and content of silicone dioxide drastically ranges. It...

Lifetime of earth dams

Tamila Titova, Rasul Akhtyamov, Elina Nasyrova & Antonia Longobardi
The level of safety of small earth dams, operating without staff and measurement and control equipment, are considered in this study. Approach enabling the possibility to define the finite lifetime (Tf) of a small earth dam here presented. The proposed approach does not require any variables monitoring. It is based on the definition of Tf by assessing the water impact on the small earth dams by quantitative methods of system analysis. To assess the earth...

Mechanical properties of the Crimean limestone, treated with material based on silicic acids

Elena Korneeva, Nikolai Vatin & Anna Dontsova
The paper describes shell-limestone treatment with stone strengthener Oxal NK 100. Aging impairs the mechanical characteristics of the stone and reduces its bearing capacity. The purpose of the study was to investigate the efficiency of the stone-strengthening composition Oxal NK 100. The composition is supposed to reduce water absorption and strengthen the stone. Cube samples of the Crimean shell-limestone were used. Several testing operations were made to reveal such specifications as absorption of water, compression...

Adaptive finite-element models in structural health monitoring systems

Alexander Belostotsky, Pavel Akimov, Oleg Negrozov, Nikolay Petryashev, Sergey Petryashev, Sergey Sherbina, Dmitry Kalichava & Taymuraz Kaytukov
The design and construction of unique buildings, facilities and complexes of “modern” architectural forms and constructive solutions in Russia began less than 20 years ago in the conditions of a shortage of national design codes and experience of such construction. Thus these objects were not provided with proper scientific and technical support and structural health monitoring (SHM) systems. Generally only the instrumental monitoring system, based on results of finite element analysis and comparison with measured...

Soil stabilization and foundation restoration using an expandable polyurethane resin

Mohanad Sabri, Konstantin Shashkin, Evgeny Zakharin & Aleksey Ulybin
The settlement of foundation is one of the main existing problems which face construction engineers during the construction operation processes since the design of a project and through the whole construction life and it leads to bad consequences on the construction. Many methods have been implemented during the last decades to stabilize the soil, lift basements and reduce further settlements. Some of these methods are actively used and effective while others are less effective, have...

Fire design methods for structures with timber framework

Marina Gravit, Dmitrijs Serdjuks, Aleksei Bardin, Vasiliy Prusakov & Karina Buka-Vaivade
Timber structures are environmentally friendly in terms of decreasing the impact of human activity on the planet. Reliability of timber structures can be provided by the corresponding fire resistance so as fire risk is one of the most significant disadvantages of timber structures. Development of new method for calculation of actual fire resistance is a topical issue. The first draft of method for calculation of actual fire resistance and classes of fire risk for load-bearing...

Expanding cements hardening within the limited deformations conditions

Igor Kharchenko, Andrey Pustovgar, Stanislav Pashkevich, Aleksey Eremin, Irina Ivanova, Yuri Bazhenov & Aleksey Kharchenko
The features of expanding cement strength and structure formation at different constrained deformation conditions were studied (without constraint of deformations, uniaxial constraint of deformations, biaxial constraint of deformations, and triaxial constraint of deformations). The study was conducted for three doses of 5 %, 15 % and 25 % of expander on the calcium sulfoaluminate basis in Portland cement of CEM 42.5 mark. For experimental data interpretation in the analysis of structure and phase composition, the...

Fire protective dry plaster composition for structures in hydrocarbon fire

Marina Gravit, Elena Golub & Sergey Antonov
The result of the combustion of fire hazardous materials at the facilities of the oil and gas complex is extensive fires, characterizing the rapid temperature rise, and as a result the destruction of load-bearing structures occurs. The dynamics of the development of such fire type requires a different approach to test the structures in order to determine the limit of fire resistance. The article presents European and American normative documents that contain methods for testing...

Quasistaticity of the process of dynamic strain of soils

Karim Sultanov, Pavel Loginov, Sabida Ismoilova & Zulfiya Salikhova
Mechanical characteristics of soil under static and dynamic strains are determined experimentally. Their accuracy and reliability depends on quasi-static nature of strain process in soil. The independence of experimental results on the wave processes is ensured. Laboratory devices of dynamic loading (DDL) have been used to determine the laws of dynamic strain and mechanical characteristics of soil. The quasi-static nature of strain process in soil on DDL is achieved solving the wave problem corresponding to...

Heating and charring of timber constructions with thin-layer fire protection

Evgeniy Polishchuk, Andrey Sivenkov & Samat Kenzhehan
The results of fire tests of constructions (beams) with fire retardant film coating in one-side fire effect under standard temperature fire regime are shown in this article. Intensity dynamics of samples heating and their charring process in thickness and along the perimeter were chosen as the key indicators. It is shown that the use of thin-layer non-swelling fire retardant coatings does not influence the intensity dynamics, in case of high-temperature exposure generates from the side...

Optimization of hybrid I-beams using modified particle swarm method

Anatoly Alekseytsev & Mohamad Al Ali
An approach for the optimization of hybrid welded I-beams based on the modification of the particle swarm method is proposed. A solution search is performed on discrete sets of variable parameters, which are taken as the size of sheets of rolled steel and steel grades. Depending on the values of the variables, a design of the support and ordinary stiffeners and their location along the length of the beam is performed. When varying the thickness...

Термонапряженное состояние массивных бетонных конструкций

Александра Васильевна Бушманова, Никита Викторович Виденков, Кирилл Владимирович Семенов, Юрий Германович Барабанщиков, Александра Вячеславовна Дернакова & Виктория Константиновна Коровина
В настоящей работе рассматривается обоснованность использования одномерных расчетных схем при анализе термонапряженного состояния массивных бетонных и железобетонных конструкций зданий и сооружений в строительный период. Приведены результаты расчетного исследования термонапряженного состояния массивной фундаментной плиты с различным соотношением плановых размеров. Особенное внимание уделено наличию/отсутствию теплоизоляции на торцах при укладки бетонной смеси. Определено, что в общем случае одномерная расчетная схема применима при соотношении h/l < 0.17, где h–меньший из плановых размеров конструкции типа плиты. Проведенное исследование показывает наличие...

The phase composition and properties of aluminate cements after early loading

Yuriy Galkin, Sergey Udodov & Lada Vasil'eva
It is widely recognized that the effect of loading at the early stages of hardening enables to increase strength characteristics of cement systems and composites based on them. Of particular interest is a study on the effect of compression of aluminate cements on physicomechanical characteristics, hydration process and phase transformations. The research focuses on maximum compressive and flexural strength, the peak intensity of the main phases and hydrate products, characteristics of DTA curves after early...

Finite element models in stresses for plane elasticity problems

Yury Tyukalov
The solution of the plane problems of elasticity theory on the basis of stress approximation is considered. To construct the solution, the additional energy functional is used. With the help of the principle of possible displacements, algebraic equations of equilibrium of the nodes of the grid of finite elements are constructed. Equilibrium equations are included in the functional of additional energy by means of Lagrange multipliers. The necessary relations for rectangular and triangular finite elements...

Cold-formed RHS T joints with initial geometrical imperfections

Marsel Garifullin, Maria Bronzova, Markku Heinisuo, Kristo Mela & Sami Pajunen
Generally, numerical simulations of structures are carried out in such a way as to most accurately repeat their real behavior. The current rules for finite element modeling of tubular joints oblige scientists and engineers to construct their numerical models considering initial imperfections. However, not all joints are sensitive to initial imperfections. Often consideration of initial imperfections brings no reasonable improvements in the accuracy of results, but severely complicates numerical simulations. In such cases, the effect...

Инженерная кинематическая теория в приложении к расчету свайных фундаментов

Владимир Сергеевич Коровкин
Автор предложил вариант расчета свайного фундамента с применением инженерной кинематической теории контактного давления грунта. Приведено решение по определению сил трения на боковую поверхность сваи дополнительно зависящее от размеров поперечного сечения внедряемой в грунт сваи. Описано решение по определению реактивного давление грунта на острие сваи или условный фундамент для всего цикла нагрузки. Рассмотрено влияние расположения плиты ростверка в свайном основании на несущую способность конструкции. Учтено взаимное влияние свай на распределение усилий в свайном ростверке. Получено решение...

The improving of the concrete quality in a monolithic clip

Anastasia Sychova, Larisa Svatovskaya, Dmitriy Starchukov, Valentina Soloviova & Marina Gravit
The article deals with the possibility of increasing strength, hardness, frost resistance, water and corrosion resistance of concrete. The reduction of its abrasion resistance and water absorption by creating a layer of nonorganic monolithic high-strength clip on its surface is also considered. The possibility of synthesis of such clip by impregnating the concrete surface with a Sol of SiO2 is shown and thermodynamically substantiated. The mathematical dependence reflecting the strength of concrete in such a...

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