scholarly journals Slinging Unit For A Hollow-Core Floor Slab Of Stand-Off Formwork

2021 ◽  
Vol 03 (09) ◽  
pp. 16-25
Author(s):  
Pulat Mirzaev ◽  
Keyword(s):  
Bearing Capacity ◽  
Technological Development ◽  
Protective Layer ◽  
Theoretical Data ◽  
The Body ◽  
Hollow Core ◽  
Utility Model ◽  
Metal Consumption ◽  
Hollow Core Slab ◽  
Full Scale Tests

Due to the fact that hollow-core slabs without formwork are produced without slinging loops (features of manufacturing technology), the issue of installation and transportation of these slabs has been solved. A constructive and technological solution is proposed for a slinging unit, arranged in the body of the slab, without the use of a slinging loop, and having only an anchor rod-dowel through which it is possible to directly sling the slab without using traditional slinging loops. The unit is designed with a reduced metal consumption and does not change the technology for manufacturing hollow-core slabs without formwork. Found and summed up a theoretical basis for calculating the bearing capacity of the proposed slinging unit, arranged in a hollow-core slab without formwork. It was revealed that the bearing capacity of the proposed slinging assembly, arranged in the body of a hollow-core slab, under the action of assembly loads, depends on the force of splitting the concrete of the protective layer located above the anchor rod-dowel of this assembly (all other things being equal). The theoretical data of the study were verified by full-scale tests of plates with slinging units arranged in their body, carried out in accordance with the proposed constructive and technological development. A utility model patent was obtained for the development of a loopless slinging unit for a hollow-core slab without formwork.

scholarly journals Loop-Free Tie-Down Node with an Anchor Rod-Dowel for a Hollow-Core Floor Slab of Formwork-Free Shaping

2020 ◽  
Vol 9 (2) ◽  
pp. 793-798
Keyword(s):  
Bearing Capacity ◽  
Technological Development ◽  
Protective Layer ◽  
Theoretical Data ◽  
The Body ◽  
Geometrical Parameters ◽  
Hollow Core ◽  
Metal Consumption ◽  
Long Line ◽  
Hollow Core Slab

When designing buildings and structures for various purposes, the specialists should find new decisions for the possibility of using structures made using the long-line formwork-free technology, including hollow-core floor slabs, namely: installation without free lengths of reinforcement, lifting without the tie-down loops, joint units with other structure elements, configuration of sections with new geometrical parameters. As the hollow-core slabs of formwork-free shaping are produced without tie-down loops, the problems of installation and transportation of these slabs are discussed. Examples of tie-down nodes installation in the slabs produced by the formwork-free shaping technology were considered in the paper, with the justification of the complexity of their installation in such slabs and the increased metal consumption. The aim is to reduce the laboriousness of rigging work and to provide a gripping device for a hollow-core slab of formwork-free shaping when removing it from a long-line pallet, storing, loading and installing this slab during the construction process. A constructive-technological decision was proposed for a tie-down node installed in the slab body without the use of a tie-down loop and having only an anchor rod-dowel through which the tie-down of a slab could be directly done without the use of traditional tie-down loops. The node was designed with reduced metal consumption and does not change the technology of manufacturing hollow-core slabs of formwork-free shaping. The theoretical basis for calculating the bearing capacity of the proposed tie-down node, installed in a hollow-core slab of formwork-free shaping was determined and summarized. It was revealed that the bearing capacity of the proposed tie-down node installed in the body of a hollow-core slab, under the action of lifting loads, depends on the splitting force of concrete protective layer located above the anchor rod-dowel of this node (all things being equal). The theoretical data of the study were validated by full-scale tests of slabs with tie-down nodes installed in their body, carried out in accordance with the proposed structural-technological development. The operational suitability of the proposed tie-down nodes with an anchor rod-dowel for the hollow-core slabs of formwork-free shaping and the possibility of their implementation at other enterprises of the country having production lines for long-line formwork-free shaping were stated. A tie-down node with an anchor rod-dowel, proposed to be installed in a hollow-core slab of formwork-free shaping, can be used in other reinforced concrete structures produced by the technology of long-line formwork-free shaping. A patent for a utility model has been received for the development of a loop-free tie-down node for a hollow-core slab of formwork-free shaping.

Bearing Capacity And Deformations When Bending The Multi-Hollow Floor Slab With Stops At The Ends (In Order Of Discussion)

2020 ◽  
pp. 26-36
Keyword(s):  
Finite Element ◽  
Bearing Capacity ◽  
Software Systems ◽  
Vertical Load ◽  
Hollow Core ◽  
Floor Slab ◽  
Finite Element Calculations ◽  
The Russian Federation ◽  
Full Scale Tests ◽  
Thrust Forces

Prefabricated multi-hollow-core slabs in precast-monolithic floors are placed in dense groups and persisted their ends in bearing beams. Various studies show that in the plane of such a floor under the action of a vertical load both along and across the slabs arise reactive thrust forces. They noticeably extinguish the load-induced forces in the sections of the slabs. This is accompanied by an increase in the bearing capacity and stiffness of the floors. But taking into account the spacer forces under modeling conditions in finite element calculations of software systems is difficult and requires additional research. By results of full-scale tests and the analysis conducted by the authors, it is established that due to the support of a multi-hollow floor slab with persisted on end faces along its axis under loading the longitudinal reactive rebuff is formed. Proposals are made to estimate its magnitude at various stages of the slabs operation up to its destruction. To ensure flat ceilings of precast-monolithic overlap, the case of supporting the plate on concrete dowels of load-bearing crossbars placed in the cavities of the plate is also considered. Based on the norms of the Russian Federation, the strength of key support units is estimated.

scholarly journals Distribution of Load Forces in Hollow Core Slabs of Precast Solid Floor Supported on Bearing Walls

2019 ◽  
Vol 18 (2) ◽  
pp. 93-103
Author(s):  
S. V. Bosakov ◽  
A. I. Mordich ◽  
A. A. Karyakin ◽  
S. A. Sonin ◽  
I. S. Derbentsev
Keyword(s):  
Hollow Core ◽  
Load Bearing ◽  
Solid Plate ◽  
Hollow Core Slab ◽  
Building Wall ◽  
Labor Inputs ◽  
Full Scale Tests ◽  
Thrust Forces ◽  
Bearing System

The need to cut construction cost of residential and public buildings and provide them with a free and transformable planning structure during their operation cause interest in building wall systems with a large step of bearing walls. In order to reduce labor inputs and increase rate of construction in such building load-bearing system it is also necessary to maximize the use of large-sized prefabricated products and minimize consumption of in-situ concrete. In this case prefabricated products should be substituted according to the conditions of local (regional) construction industry base and volume of in-situ concrete must be sufficient to ensure a complete redistribution of internal forces between elements of the bearing system under load. As for the described bearing wall system of a multi-storey building the paper presents a flat precast solid floor formed by hollow-core slabs and monolithic crossbars supported by load-bearing walls. The hollow-core slabs supported at the ends on cast-in-place crossbars in the planes of bearing walls are arranged in dense groups between cast-in-place braced cross-beams. Dense contacts between overlapping elements are fixed by internal bonds. New data on distribution of forces in floor elements under the action of a vertical load have been obtained on the basis of full-scale tests and existing theoretical assumptions. It has been established that due to this load reactive thrust forces ensuring an operation of every hollow-core slab group in the floor as an effective solid plate supported along the contour have been originated in the floor plane along two main axes. Calculation of the reactive thrust forces makes it possible more accurately to assess a load-bearing capacity and rigidity of the precast solid floor and to increase a step of bearing walls up to 8 m and more while having hollow-core slabs with a thickness of 220 mm.

scholarly journals A study on the behavior of beam-column connections in precast concrete structures: experimental analysis

2012 ◽  
Vol 5 (6) ◽  
pp. 848-873 ◽  
Author(s):  
M. N. Kataoka ◽  
M. A. Ferreira ◽  
A. L. H. C. El Debs
Keyword(s):  
Experimental Analysis ◽  
Precast Concrete ◽  
Concrete Structures ◽  
Concrete Cover ◽  
Experimental Results ◽  
Hollow Core ◽  
Multistory Buildings ◽  
Cracking Control ◽  
Hollow Core Slab ◽  
Reinforcement Distribution

Due to the large increase in the use of precast concrete structures in multistory buildings, this work covers a study on the behavior of beam-column connection with emphasis on the continuity provided by the slab reinforcement. Two prototypes were tested, each one with a different detail of the continuity reinforcement distribution. In both connections, the steel area used on the concrete cover of the hollow core slab was the same, varying the amount of bars that passed through the column and the ones that were placed adjacent to the column. The experimental results showed that the connection with bars adjacent to the column presented stiffness increase and a better cracking control. According to the classification the two tested connections can be considered semi-rigid.

scholarly journals Determination of reinforcing bars for tests of hollow core slabs with continuity

2013 ◽  
Vol 6 (6) ◽  
pp. 903-932
Author(s):  
A. P. Santos ◽  
M. A. Ferreira ◽  
R. C. Carvalho ◽  
L. M. Pinheiro
Keyword(s):  
Shear Strength ◽  
The Other ◽  
Hollow Core ◽  
Reinforcing Bars ◽  
Simply Supported ◽  
Resistance Moment ◽  
Hollow Core Slab ◽  
Maximum Shear Strength

The structural designs of floors formed by hollow core slabs usually consider these as simply-supported slabs. In recent years there have been project changes and hollow core slabs with continuity are widely used. The objective of this study is to suggest a way to calculate the reinforcement bars to be used in tests with continuity provided by a structural topping. Thus, this paper presents a method based on the maximum positive resistance moment and maximum shear strength of a hollow core slab. The method is applied to a test in hollow core slab specimens which have the following dimensions: 2 m width, 6 m long, and 21 cm high. The results indicated that the method was satisfactory to the performed test, and can therefore be applied to the other test configurations or even designs.

scholarly journals ANALYTICAL AND NUMERICAL METHODS FOR DETERMINING THE CARRYING CAPACITY OF A PILE BARETT ON WEAK SOILS IN DEEP PITS

2021 ◽  
Vol 17 (3) ◽  
pp. 94-101
Author(s):  
Rashid Mangushev ◽  
Nadezhda Nikitina ◽  
Hieu Le Trung ◽  
Ivan Tereshchenko
Keyword(s):  
Bearing Capacity ◽  
Numerical Test ◽  
Full Scale ◽  
Construction Site ◽  
Weak Soils ◽  
Geological Conditions ◽  
Full Scale Tests ◽  
Soil Excavation ◽  
Deep Pits ◽  
The City

The article provides an analysis of the bearing capacity of barrett piles in difficult geological conditions at a construction site in the city of Hanoi, Vietnam based on the results of analytical calculations according to Russian building codes, mathematical modeling and field full-scale tests. The paper describes a numerical test of a single barrette for Mohr-Coulomb and Hardening Soil models in the Midas GTS NX software package. The bearing capacity of a barrette in soft soils is also proposed to be determined by an analytical solution for calculating the settlement of a single pile, taking into account the unloading of the pit after soil excavation. The results of full-scale tests at the site of future construction, graphs of "load-settlement" of the barrette head from the applied vertical load and the general assessment of the bearing capacity of the barret pile by various methods are shown.

scholarly journals TECHNICAL CONDITION OF CORRUGATED METAL TRANSPORT STRUCTURES

2021 ◽  
pp. 38-50
Author(s):  
J. J. LUCHKO ◽  
V. V. KOVALCHUK
Keyword(s):  
Bearing Capacity ◽  
Technical Condition ◽  
The Body ◽  
Soil Environment ◽  
Metal Structures ◽  
Advantages And Disadvantages ◽  
Methods Of Calculation ◽  
Analysis And Synthesis ◽  
The Impact ◽  
Corrugated Metal

Purpose. The purpose of the work is to establish the real technical condition of transport structures made of corrugated metal structures on the basis of the analysis of scientific and technical sources.And to analyze the experience of operation of metal corrugated structures in the soil environment and to form and generalize the problems of ensuring the reliability and durability of structures made of metal corrugated structures in the conditions of operation on railways and highways of Ukraine. Methodology. To achieve this goal, a review of scientific and technical sources and regulations of different countries on the technical condition of transport facilities in Ukraine was conducted. In particular, data on the distribution of bridges and pipes made of corrugated metal structures by mode of transport are given. It is shown that the development and implementation of new technologies for the repair of existing defective pipes and small bridges, both on the railways and highways of Ukraine is a very important issue. A thorough analysis of the experience of operation of corrugated metal structures in the soil environment in different countries was conducted. Data on the main inadmissible defects of pipes and the reasons of their development are given. CMS' (corrugated metal structures) corrosion and other defects are given. A number of examples of overpass defects, collapse of bridges and structures with MCS in operation are presented. The qualitative indicators of metal corrugated structures, their advantages and disadvantages are also considered, the problems and the analysis of ensuring the reliability and durability of the structures with CMS in the conditions of operation on the railways and highways of Ukraine are formulated. Findings. An analysis of domestic and foreign scientific and technical sources on the technical condition of transport facilities in Ukraine was conducted. In particular, the experience of operation of corrugated metal structures in different countries of the world is studied and generalized. The analysis and synthesis of problems of ensuring the reliability and durability of buildings with CMS in the conditions of operation on the railways and highways of Ukraine. Originality. As a result of the analysis of the technical condition of transport facilities operated on railways and highways of Ukraine, it was found that about 15 % of transport facilities – small and medium bridges and culverts on Ukrainian railways and about 45 % of transport facilities on Ukrainian roads have unacceptable defects and require immediate repair and replacement. Also, it was established on the basis of research that there are no methods for assessing the load-bearing capacity of transport facilities with CMS in the presence in the body of the embankment of the railway or highway metal corrugated structures with a diameter greater than 6 m. It was determined that standards don't include regulations on design and monitoring of CMS on railway tracks. Practical value. On the basis of these data it was possible to offer directions of theoretical and experimental research and methods of calculation, tests of CMS and diagnostics of a technical condition of transport structures with CMS. In particular, the measurement of the impact of the environment on the bearing capacity of the CMS and the measurement of residual deformations of the corrugated metal pipe on the railway track. Execution of the analysis and synthesis of methods of calculation of transport constructions with CMS will lead to improvement of methods of calculation of CMS.

scholarly journals Rabbit Dietary Supplementation with Echinacea purpurea L.: The Quality Profile of Rabbit Meat

2020 ◽  
Vol 50 (2) ◽  
pp. 185-193
Author(s):  
Roman Voroshilin ◽  
Marina Kurbanova ◽  
Sergey Rassolov ◽  
Elena Ul'rih
Keyword(s):  
Technological Development ◽  
Saturated Fatty Acids ◽  
Echinacea Purpurea ◽  
The Body ◽  
Feed Additive ◽  
Control Group ◽  
Meat Production ◽  
Rabbit Meat ◽  
Positive Effect ◽  
Experimental Group

Introduction. Rabbit meat is an excellent source of dietetic food. High-quality and safe meat production is a priority of the scientific and technological development of the Russian Federation. The research objective was to determine the optimal dose of Echinacea purpurea L. extract in the rabbit diet and study its effect on the physicochemical and morphological quality parameters of rabbit meat. Study objects and methods. At 70 days of age, the experimental animals started to receive various doses of a phytobiotic feed additive based on the Echinacea purpurea extract. The experiment lasted 30 days. Results and discussion. The daily dose of 1.0 g and 1.5 g per animal proved to stimulate the redox processes in the rabbit metabolism. The body weight of the test animals significantly increased compared with the control group. The test slaughter revealed a high level of meat productivity. The animals in experimental groups II and III showed the best slaughter indicators. Each animal received 1.5 g of the extract per day. The morphological composition of chilled carcass indicated that the additive had a positive effect on the mass indicators. According to the physical and chemical analysis, the contents of water, protein, and ash in the experimental group was the same as in the control group. The ratio of unsaturated and saturated fatty acids in the control group was 1.34:1, while in the experimental group III is was 1.39:1. This optimal proportion proved a high biological value of rabbit meat, which makes it a dietary product. The phytobiotic additive proved commercial as the test animals demonstrated an intensive weight gain compared with the control group. Experimental groups II and III showed the best slaughter indicators. Conclusion. 1.5 g of the extract of Echinacea purpurea had a positive effect on the composition and physicochemical parameters of rabbit meat, as well as meat production.

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