scholarly journals Technical and economic efficiency of the use of foundations in rammed pits according to sounding data during dynamic tests

2019 ◽  
Vol 6 (4) ◽  
Author(s):  
Olga Galimnurova ◽  
Ilya Galimnurov ◽  
Nikita Samofeev ◽  
Regina Harisova
Keyword(s):  
Bearing Capacity ◽  
Dynamic Control ◽  
Cumulative Effect ◽  
Soil Conditions ◽  
Building Structures ◽  
Labor Costs ◽  
Material Consumption ◽  
Technological Parameters ◽  
Foundation Pit ◽  
Semi Solid

The construction of foundations is one of the material-intensive and time-consuming areas in the practice of construction. The attempt to reduce material consumption and laboriousness helps to improve the variability of choice among foundations in rammed pits. Due to soil compaction and increase of its bearing capacity, this type of foundations allows to reduce material consumption, just as concreting without formwork – to reduce the laboriousness of the work. Foundation pits are not excavated, but rammed to the required depth by tamping, followed by concreting of the formed foundation pit or with the installation of prefabricated reinforced concrete elements. The article describes the method of dynamic control of the bearing capacity of foundations in rammed pits according to the technological parameters of ramming in different soil conditions (from semi-solid to soft plastic consistency) and contains empirical values and formulas. The authors show the basic conditions for the formation of pit rams, the formed zones and changes in the properties of soils and their texture, strength indicators, providing sufficient safety for building structures. The advantage of using foundations in rammed pits is ensured by the combined effect of their implementation, where its value heavily depends on specific construction conditions and can be achieved by: reducing the cost of design and survey work; when choosing the least costly structural solution to the foundations; a significant reduction in labor costs during the construction and installation work of the zero cycle of buildings for various purposes. The authors tested the results of this research during the construction of the facilities of OJSC “Neftmontazh” and the cumulative effect of the use of rammed pits in the amount of more than 700 thousand rubles was achieved.

scholarly journals SOME TECHNOLOGICAL PARAMETERS OF VIBRATION CENTRIFUGAL EQUIPMENT AS A FACTOR IN CONTROL OF CONCRETE PROPERTIES

2021 ◽  
Vol 6 (1) ◽  
pp. 8-19
Author(s):  
M. Nazhuev ◽  
P. Dzhamilova ◽  
F. Bataeva ◽  
Z. Bakaev ◽  
A. Kukaev ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Experimental Studies ◽  
Building Structures ◽  
Technological Parameters ◽  
Cross Sectional ◽  
Technological Factors ◽  
Integral Characteristics ◽  
The Cost ◽  
Concrete Elements ◽  
Centrifugal Equipment

An increase in the volume of construction requires innovations in technological, structural and design solutions for reinforced concrete elements. As a result of the centrifugation method, variatropic concretes with different cross-sectional characteristics and structures made from them. Therefore, at the stages of calculation and design of building structures of a variatropic structure, an unreasonably large supply of bearing capacity is usually laid, leading to an impressive rise in the cost of promising building structures. It is proposed to combine centrifugation with vibration to increase the density and ensure a more uniform distribution of the components of the concrete mixture over the wall thickness of an annular section product, in particular columns. Vibration will be ensured through the use of clamps, which are put on the shafts of the installation. Within the framework of the proposed experimental setup for creating vibrocentrifuged samples of annular cross-section with a variatropic structure and a method for their manufacture, the technological parameters of vibration are identified, which have the most significant effect on the characteristics of vibrocentrifuged concrete. In the experiments, the following technological factors varied: the height of the technological protrusions of the clamps and the vibration mode. The problem of assessing the influence of these factors on the integral characteristics of concrete is investigated. The results of experimental studies of the influence of the considered technological factors on the integral characteristics of vibrocentrifuged concrete are presented. The results obtained show the feasibility of continuing the study of rational technological parameters of vibrocentrifugation to improve the characteristics of concrete and regulate its variatropy, which will allow the proposed method to be patented in the future and to design an improved vibrocentrifuged column with more fully utilized reserves of the bearing capacity of building structures.

scholarly journals DESIGN OF REINFORCEMENT OF FOUNDATIONS OF RECONSTRUCTED, RESTORED BUILDINGS USING PILES

2020 ◽  
Vol 11 (4) ◽  
pp. 33-45
Author(s):  
A. I Polishchuk ◽  
I. V Semyonov
Keyword(s):  
Bearing Capacity ◽  
Soil Layer ◽  
Shallow Foundations ◽  
Soil Conditions ◽  
Building Structures ◽  
Building Structure ◽  
Construction Site ◽  
Structural Elements ◽  
Before And After ◽  
Design Loads

The procedure for designing reinforcement of shallow foundations of reconstructed, restored buildings using piles (injection, bore injection, composite pressed, screw, etc.) is considered. At the first stage of the design, the constructive solution of the existing foundations, the structural diagram of the building (structure), as well as the loads transferred to the building structures before and after the reconstruction (restoration) of the building are established. An assessment of the soil conditions of the construction site of the building being reconstructed is carried out; a bearing soil layer is identified for deepening the lower ends of the piles. Based on the data obtained, the loading of the base of the foundations of the reconstructed (restored) building is assessed and the need for their strengthening (or their further operation without reinforcement) is established. In the event that strengthening of the building foundations is required, the method of transferring the additional load to the piles is chosen. After that, the bearing capacity of the piles and the design loads allowed on the piles are substantiated. The design of foundations is carried out taking into account their reinforcement with piles, as well as verification calculations of the base of reinforced foundations (combined) for the first and second groups of limiting states (for bearing capacity and deformations). In accordance with the regulatory documents, strength calculations of the main structural elements of foundations are performed, which are necessary to ensure their full-fledged operation, taking into account reinforcement. At the final stage, working documentation is developed to strengthen the foundations of the reconstructed, restored building (structure). The presented algorithm for the design of strengthening the foundations of reconstructed, restored buildings using piles allows to correctly and consistently organize the work of specialists.

USE OF ACRYLIC COPOLYMER ADDITIVE SOIL STABILIZATION PLUS FOR PREPARATION OF MIXTURES MADE BY COLD RESYCLING TECHNOLOGY AND CRUSHED STONE-SAND MIXTURES IN PAVEMENT FOUNDATION LAYERS

2021 ◽  
Vol 2021 (24) ◽  
pp. 48-59
Author(s):  
Anatolii Mudrychenko ◽  
◽  
Ivan Balashov ◽  
Sergey Illyasch ◽  
◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Soil Stabilization ◽  
Crushed Stone ◽  
Technological Parameters ◽  
Acrylic Copolymer ◽  
Sand Mixture ◽  
Recycling Technology ◽  
Complex Binder ◽  
Cold Recycling ◽  
Pavement Foundation

ntroduction. Rehabilitation of public roads network requires a comprehensive recovery with strengthening of the bearing capacity of the pavement foundation. Rehabilitation of the foundation bearing capacity performed by arranging layers of road material made by cold recycling technology (hereinafter — CRRM) in accordance with [4] or by arranging a layer of crushed stone — sand mixture reinforced with cement or complex binder (hereinafter — CSSM 20) according to [13]. Purpose. The purpose of the work is to study the feasibility of using acrylic additives for the preparation of mixtures made by cold recycling technology and crushed stone-sand mixtures treated with cement in the layers of pavement foundation. Materials and methods. Experimental comparative tests of CRRM and CSSM 20 with different content of complex binder were performed. Results. Feasibility of acrylic additives use has been established (hereinafter — the additive) for the preparation of CRRM and CSSM 20 in the pavement foundation layers. Recommendations on technological parameters of preparation, transportation, laying and compaction of mentioned mixtures are given. Conclusions. Performed researches have shown that according to physical and mechanical indicators CRRM and CSSM20 meet the requirements of the current normative documents of Ukraine. The advantages of use are noted.

scholarly journals Ultimate Compressive Strains and Reserves of Bearing Capacity of Short RC Columns with Basalt Fiber

2021 ◽  
Vol 11 (16) ◽  
pp. 7634
Author(s):  
Aleksandr V. Shilov ◽  
Alexey N. Beskopylny ◽  
Besarion Meskhi ◽  
Dmitry Mailyan ◽  
Dmitry Shilov ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Basalt Fiber ◽  
Lightweight Aggregate ◽  
Short Fiber ◽  
Hydraulic Press ◽  
Steel Reinforcement ◽  
Fiber Reinforced Concrete ◽  
Material Consumption ◽  
Short Columns

Increasing the bearing capacity of reinforced concrete structures, reducing material consumption, and ensuring quality are critical in modern construction. The article presents an experimental study of the ultimate compressive strains of short fiber basalt reinforced concrete columns and provides recommendations for increasing the bearing capacity using steel reinforcement bars with greater strength. The columns were tested in an upright position using a hydraulic press. Strains were measured with dial indicators and a strain gauge station. It was shown that the addition of 10% coarse basalt fiber increased the ultimate compressibility of concrete on ordinary crushed stone by 19.8%, and expanded clay concrete by 26.1%, which led to the strain hardening of concrete under compression by 9.0% and 12%, respectively. Ultimate compressive strains in fiber-reinforced concrete short columns with combined reinforcement increased 1.42 times in columns on a lightweight aggregate and 1.19 times on heavy aggregate. An increase in the ultimate compressibility of concrete makes it possible to use steel reinforcement with greater strength in compressed elements as the concrete crushing during compression occurs primarily due to the reaching of critical values by tensile stresses in the transverse direction. This makes it possible to manufacture structures with a higher load-bearing capacity and less material consumption. A practical example of the application of the proposed approach is given.

Mathematical Modeling of the Test Process of Construction Materials

2019 ◽  
Vol 828 ◽  
pp. 115-120 ◽  
Author(s):  
Narine Pirumyan ◽  
Mihran Stakyan ◽  
Gagik Galstyan
Keyword(s):  
Mathematical Modeling ◽  
Building Materials ◽  
Computational Algorithm ◽  
Least Squares Method ◽  
Construction Materials ◽  
Building Structures ◽  
Technological Parameters ◽  
Processing Data ◽  
Optimization Principle ◽  
Test Process

A mathematical model has been proposed for processing data from tests of building materials and obtaining optimal links between the characteristics of the bearing capacity and technological parameters of building materials for the use of these connections in refined design and construction procedures for building structures. To improve the accuracy of the results obtained, a three-level optimization principle was applied using the least squares method and a computational algorithm was compiled that allows us to develop an additional computational subroutine expanding the capabilities of the corresponding standard computer programs.

Analysis of the Bearing Capacity of Adhesive Joint of Honeycomb Cores of Sandwich Structures with the Continuous Adhesive Layer

2020 ◽  
Vol 864 ◽  
pp. 228-240
Author(s):  
Andrii Kondratiev ◽  
Oksana Prontsevych ◽  
Tetyana Nabokina
Keyword(s):  
Bearing Capacity ◽  
Adhesive Joint ◽  
Sandwich Structures ◽  
Adhesive Layer ◽  
Honeycomb Structure ◽  
Bonding Process ◽  
Aluminium Foil ◽  
Honeycomb Core ◽  
Technological Parameters ◽  
Depth Of Penetration

Adhesive sandwich structures with the honeycomb core of the metallic foil, polymeric papers and composites are widely and effectively used in the units of aerospace engineering and in the other industries owing to a number of undeniable advantages, including high specific strength and stiffness. In the process of designing and manufacturing of abovementioned structures, it is necessary to ensure high strength and reliability of the adhesive joint of the bearing skins and honeycomb core at a small area of their contact. The decisive factors influencing the bearing capacity of such joint are the technological parameters of the bonding process. Using the finite element modeling, the paper deals with the bearing capacity of the adhesive joint of bearing skins with the honeycomb core based on the aluminium foil and polymeric paper Nomex at transversal tearing for the key factors of the bonding process. The pattern of the adhesive joint failure (on the adhesive of honeycombs) has been revealed, depending on the depth of penetration of honeycombs ends in the adhesive, physical and mechanical characteristics of honeycombs, modulus of elasticity and tearing strength of the adhesive and thickness of the adhesive layer. Peculiar features of behavior of adhesive joints of the bearing skins with the honeycomb core based on the aluminium foil and polymeric paper Nomex under the load have been established, which should be taken into account in designing and manufacturing of honeycomb structures. The recommendations are given with regard to choosing of parameters of the process of honeycomb structure bonding, which allow providing with the acceptable accuracy the optimal depth of penetration of ends of the honeycomb core faces in the adhesive layer of specified depth.

scholarly journals Study on Flexural Bearing Capacity Calculation Method of Enclosure Pile with Partial Excision in Deep Foundation Pit

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Mingfeng Lei ◽  
Linghui Liu ◽  
Yuexiang Lin ◽  
Jin Li
Keyword(s):  
Flexural Strength ◽  
Bearing Capacity ◽  
Calculation Method ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Theoretical Derivation ◽  
Deep Foundation Pit ◽  
Practical Engineering ◽  
Capacity Calculation ◽  
Partial Excision

During deep foundation pit construction, the structural clearance intrusion, which is caused by the complex formation conditions and the inefficient drilling equipment, is usually detected due to the vertical deviation of piles. To meet construction requirements, pile parts intruding into the structural clearance are supposed to be excised. However, the sectional flexural strength of the pile is bound to decrease with partial excision, which would reduce the bearing capacity of the enclosing structure during construction. In this paper, a theoretical derivation of the normal sectional flexural strength of the partially excised circular pile is proposed. The derivation adopts the assumption of the plane section and steel ring equivalence and can be solved by the bisection method. Furthermore, the calculation method is applied to the pile evaluation of a practical engineering; also, the method is verified by the numerical method. The application results show that the excision of rebar and pile’s sectional area will cause a rapid linear decline in the sectional flexural strength. After excising 18 cm radial thickness of the circular pile (ϕ800 mm) and 6 longitudinal rebars, the sectional flexural strength of the pile decreases to 58% from the origin, which cannot meet the support requirement. The analysis indicates that pile reinforcements must be carried out to maintain the construction safety.

Study on Rheocasting-Rolling of Semi-Solid AZ31B Magnesium Alloy

2010 ◽  
Vol 146-147 ◽  
pp. 1557-1560
Author(s):  
Ying Zhang ◽  
Jin Hua Xu ◽  
Shui Sheng Xie ◽  
Mao Peng Geng ◽  
Hong Min Guo ◽  
...  
Keyword(s):  
Magnesium Alloy ◽  
Hot Rolling ◽  
Technological Parameters ◽  
Az31b Magnesium Alloy ◽  
Semi Solid

Analysis on microstructure of semi-solid AZ31B magnesium alloy produced under different technological parameters were done, hot rolling experiments of AZ31B magnesium alloy semi-solid strips were carried out on the rheocasting-rolling machine which was developed by ourselves. The result shows that the strips after the rheocasting-rolling of AZ31B semi-solid magnesium alloy have good plasticity and rolling properties, this offers theory basis for reprocessing of AZ31B.

The Increasing Laws of the Foundation Strength and Civil Engineering

2011 ◽  
Vol 250-253 ◽  
pp. 2662-2666
Author(s):  
Zhi Hai Qin ◽  
Tong Dong Li
Keyword(s):  
Water Stress ◽  
Bearing Capacity ◽  
Pore Water ◽  
Effective Stress ◽  
Civil Engineering ◽  
Building Construction ◽  
Foundation Pit ◽  
Engineering Construction ◽  
Building Load ◽  
Over Time

In the civil engineering construction, with the building load of building construction or adding storeys, foundation pit dewatering, embankment filling , over time, the pore water stress that is borne by pore water in the foundation decreases gradually, the effective stress that is borne by particle increases gradually, the foundation bearing capacity increases gradually, we use different methods to derive the variation law in the theoretical solution, and carry on the comparison, then get the same conclusion. By using theory to solve the frequently encountered problems during civil engineering construction, including the problems of building construction or adding storeys, foundation pit dewatering, embankment filling, it provides theory basis for both economical and safe civil engineering construction .

Combined seismic base shear and torsional loading provisions in the 1990 edition of the National Building Code of Canada

1991 ◽  
Vol 18 (6) ◽  
pp. 945-953
Author(s):  
A. M. Chandler
Keyword(s):  
Ground Motions ◽  
Building Code ◽  
Soil Conditions ◽  
Building Structures ◽  
Base Shear ◽  
Ground Acceleration ◽  
Period Range ◽  
Natural Period ◽  
Short Period ◽  
Edge Response

This paper evaluates the earthquake-resistant design provisions of the 1990 edition of the National Building Code of Canada (NBCC 1990) for asymmetric building structures subjected to combined lateral shear and torsional dynamic loadings arising from earthquake base excitation. A detailed parametric study is presented, evaluating the dynamic edge displacement response in the elastic range, for the side of the building which is adversely affected by lateral–torsional coupling. A series of buildings is studied, with realistic ranges of the fundamental natural period, structural eccentricity, and uncoupled frequency ratio. These buildings are evaluated under base loadings arising from a total of 45 strong motion records taken from earthquakes in North America, Mexico, Europe, the Middle East, and Southern Pacific, categorized according to site soil conditions and the ratio a/v of peak ground acceleration to velocity. The latter parameter together with the uncoupled lateral period are found to influence strongly the combined dynamic edge response, with the greatest forces on edge members arising from earthquakes with high a/v ratio in structures with natural periods below 0.8 s. In this case the NBCC 1990 loading provisions significantly underestimate the elastic dynamic response. For buildings with periods longer than 0.8 s, the conservatism of the base shear provisions leads to overestimation of combined dynamic edge response in asymmetric systems, and this is also true in the short-period range for buildings subjected to ground motions with low a/v ratio. The NBCC 1990 provisions are reasonably conservative for short-period systems subjected to ground motions with intermediate a/v ratio. Key words: earthquakes, seismic, design, response, spectra, base, shear, torsional, provisions.

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