70 Works

The critical ventilation velocity for transverse double fires in tunnel

Qiuyi Zhang & Guihong Pei
The critical velocity of longitudinal ventilation is one of the most important parameters in tunnel fires. Most previous studies simulated fire scenarios in which only one fire source exists in the tunnel. However, the critical velocity will change under the condition of transverse double fires. In this study, the critical ventilation velocity under the transverse double-fire condition compared with the single fire source was analyzed by using the Fire Dynamics Simulator (FDS). The results show...

Additional load on barrel vaults of architectural monuments

Anay-Khaak Kaldar-Ool, Vladimir Babanov, Boris Allahverdov & Svetlana Saaya
In old buildings, which are architectural monuments, the stone three-centered barrel vaults and arches have been often used. In case of reconstruction of old buildings, it becomes necessary to increase the load on these elements. Calculation of additional load is based on instrumental examination of the vaults. While creating an analytical model of a barrel vault, it is necessary to use the experimental results of determination of the vault geometric parameters and material strength characteristics....

Reliability estimation of industrial building structures

Sergii Pichugin
The article is devoted to solving the problem of the reliability of industrial building structures: crane and roof beams, columns, redundant building systems. For this aim, the probabilistic method of structural reliability estimation is developed after the criterion of bearing strength, in which the main component of structure reliability is faultlessness. The method takes account of the random loads and material strength, loads joint action, the specific character of work and failure elements, nodes and...

Constructive-technological decisions in regulating the flow of atmospheric precipitation

Olga Degtyareva, Georgy Degtyarev, Nikolai Lavrov & Djouhar Aliev
Practically all sources of fresh water suitable for agriculture, water supply to the population and vacationists, as well as for industrial development on the Black Sea coast of the Caucasus either have completely exhausted themselves or are on the verge of their possibilities. Further development of the region is directly related to the resolution of this problem. The solution of the problem is possible when the system for regulating precipitation flow is implemented. The proposed...

Properties and thermal insulation performance of light-weight concrete

Tang Lam, Dinh Tho Vu, Vu Kim Dien, Boris Bulgakov & Elena Anatolyevna Korol
The building energy performance is becoming increasingly important, because of environmental restrictions and rising costs of fuel end energy. Therefore, improve the thermal insulation performance of wall covers of buildings is crucial. The present study evaluated the combined effects of two types of materials of expanded polystyrene (EPS) beads and unprocessed fly ash (FA) in Vietnam on properties of light-weight concrete (LWC). The calculation of mixture proportions of LWC is applied in accordance with the...

Residual resource of a one-storey steel frame industrial building constructed with bridge cranes

Tatiana Zolina & Pavel Sadchikov
The scheme of an integrated approach to the study of changes in the stress-strain state of the frame one-story industrial building constructed with bridge cranes, caused by accumulation of damage caused during the operation. The algorithm has been developed for estimating and predicting the residual resource of a production facility on the basis of processing the results of a series of surveys. It allows to obtain the values of reliability indicators in the correlation approximation...

Fiber concrete for the construction industry

Sergey Klyuev, Alexander Klyuev & Nikolai Vatin
The article considers the use of dispersed concrete reinforcement. The efficiency of reinforcing of concrete by a fiber is proved as its strength and deformative characteristics increase. For receiving composite binders were used: Portland cement of TsEM I 42.5H GOST 31108-2003 (Russian State Standard), blast furnace granulated slag with Mo =1.14 and Ma = 0.2, mineral plasticizer Tricosal 181 softener in essence supplementing particle size distribution knitting, waste of wet magnetic separation of ferruterous quartzites...

Implementation of pulse heat supply for dependent connection of customers

Andrey Makeev
This article deals with organization of pulsed and fluctuating circulation of heat-carrying agent in separate sections of heat supply system with dependent connection of customers. These types of oscillatory motion of the heat-carrying agent are proposed to be carried out in a self-sustained operation on the basis of the hydraulic ram operation principle. The relevance of the subject-matter is determined by the influence of oscillating flows on the intensity of heat exchange processes and by...

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...

Improvement of the soil deformation modulus using an expandable polyurethane resin

MOHANAD SABRI & Constantin Shashkin
Different methods are used in the field for foundations remediation and improvement of the soil properties, but every method has its advantages and limitations. Moreover, not all the existing methods are able to stabilize the soil and elevate the foundations effectively, regulating the process depending on the desired results. The settlements of the foundations of the buildings and structures lead to negative consequences and controlling the settlements is complex itself essentially in the type of...

Composition calculation and cracking estimation of concrete at early ages

Tang Lam, Chuc Nguyen, Boris Bulgakov & Pham Anh
Recently, variety of large-scale constructions from monolithic concrete structures have been built in different regions of Vietnam. The application fields of these structures are extensive including the marine construction, underground structures, the high-rise building erection and others. However, structures damage and cracking, caused by temperature stresses, become more popular and strong impact on operation reliability and durability. In this study, the American standard ACI 211.1-09 was used to determine the composition of heavyweight concrete for...

Strength and phase composition of autoclaved material: an approximation

Gennady Ovcharenko & Danil Gilmiyarov
The purpose of this work was to identify the relationship between the phase composition and strength of autoclaved pressed stone from a mixture of lime and ash of CHP in the presence of Na2SO4. From these mixtures are made such building materials as silicate brick and blocks from autoclaved cellular concrete. The phase analysis of the autoclaved samples was carried out by X-ray and thermal methods. It was found that the mixtures studied after autoclaving...

Suspension structure with cross-laminated timber deck panels

Karina Buka-Vaivade, Dmitrijs Serdjuks, Vadims Goremikins, Leonids Pakrastins & Nikolai Vatin
Innovative suspension structure with prestressed cable trusses as the main load-bearing members was developed. Cross-laminated timber panels of the deck are placed to the bottom chords of the prestressed cable trusses. The structure with the deck panels placed to the bottom chord with the clearances and behaves in bending in the transversal direction only, and the structure with the deck placed without clearances and behaves in bending in the transversal direction and in compression in...

Ultimate state of the support zone of reinforced concrete beams

Vladimir Travush, Sergey Krylov, Denis Konin & Alexey Krylov
A brief review of actual methods of calculation of the shear forces is performed; the calculated dependences are analyzed and their estimation is given. The shortcomings of the methods are noted, the main one is the empirical approach to the solution of the problem. The features of destruction of reinforced concrete elements along an inclined section are considered; the mechanism of destruction, on which the actual normative documents are based, is analyzed. A method of...

Composite binders for concretes with improved shock resistance

Roman Fediuk, Valeriy Lesovik, Yuriy Liseitsev, Roman Timokhin, Aleksandr Bituyev, Mikhail Zaiakhanov & Aleksandr Mochalov
The qualitative and quantitative composition and properties of the initial materials, composite binders and concrete samples were studied. Optimal compositions of concrete for protective structures that provide the maximum static and dynamic strength characteristics are selected. In this case, the effect of increasing the shock endurance increases to 6 times. It has been found that concretes with a small number of defects, high packing density and uniformity, good adhesion between the aggregate and cement stone,...

Modified water-cement ratio rule for the design of air-entrained concrete

Leonid Dvorkin
Designing concrete compositions, containing entrained air, is usually done by means of empirical proportioning, which is quite a laborious and lengthy process. In the article design formulae are experimentally justified with rule of modified C/W, which is complex due to known empirical dependencies, and allow us to find the content of concrete components with desired strength, frost resistance, and density properties. Conducted experimental studies are: compression method for determining the volume of entrained air as...

Calculation method of bending plates with assuming shear deformations

Yury Tyukalov
The problem of calculating bending plates by the finite element method with considering of shear deformations is considered. The bending plates are widely used as common structures of various objects of civil and industrial construction. The solution was obtained on the basis of the principles of the minimum of additional energy and possible displacements. For approximation of moment fields, piecewise constant functions are used. Shear forces can be approximated by constant or piecewise constant functions....

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...

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...

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...

The periodic temperature oscillations in a cylindrical profile with a large thickness

Oleg Samarin
A hollow cylinder with thick walls is one of the most complex objects to calculate the unsteady temperature field, so this field is the least studied. However, such objects are found in many modern constructions of systems of generation and distribution of heat. In the proposed work it deals with the study of propagation of temperature waves in the wall of the hollow cylinder with harmonic temperature change of external environment arising from its diurnal...

Heat loss through the window frames of buildings

Albert Baiburin, Mikhail Rybakov & Nikolai Vatin
The object of investigation is window frames of buildings since they are critical zones in terms of thermal insulation. It was studied how the properties of window frame affect the change in heat flow and temperature fields. It was analyzed the heat loss that depends on a range of structural features of a window frame, such as geometrical, thermal and physical properties of walls, windows, lintels, and joints. An experiment was designed, computer simulation and...

Structural health monitoring of a concrete-filled tube column

Omid Rezaifar
Structural Health Monitoring (SHM) has provided an opportunity to assess the reliability and integrity of civil engineering structures. Damage in the structure reduces the hardness and modal properties of the structures. Therefore, changes in dynamic behavior and modal data can be used to identify damage. This study identifies the existence and location of damage in the CFT column based on vibrational analysis techniques. The method for damage detection is based on dynamic analysis on the...

Numerical simulation of the turbulent flow over submerged bridge decks

Thi Kim Chi Thai
Today climate change is one of the most significant threats and global issues that should be concerned. It causes the increased number of natural disasters such as hurricanes, storms, typhoons and floods. Under these critical hydrological conditions, transportation infrastructure includes bridges easily got submerged, damaged and lead to its failures. Evaluation of bridge stability, hydrodynamic forces acted to bridges and understanding the complex flow behavior in particular during and after flooding plays an important role...

Thermal-insulation boards from fibrous plant wastes and urea-formaldehyde binder

Tatiana Vahnina, Irina Susoeva & Andrey Titunin
Irreversible waste spinning flax and cotton are sent to landfill or incinerated, it adversely affects the environment, although it is desirable to use plant waste for production, which would be a very positive approach in terms of natural environment. Composite boards of irrecoverable waste from the processing of flax and cotton and urea-formaldehyde binder (UF) can be used as a thermal-insulation material, the development of this composite material is the purpose of this research. The...

Registration Year

  • 2019
    70

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  • Text
    70

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  • Magazine of Civil Engineering
    70