On the Influence of Cross-Section and Reinforcement of Reinforced Concrete Constructions on the Concentration of Coarse Aggregate in Concrete with Frame Structure

2020 ◽  
Vol 1011 ◽  
pp. 66-71
Author(s):  
Grigorii Nesvetaev ◽  
Evgenii Lesniak ◽  
Aleksei Kolleganov ◽  
Nikita Kolleganov
Keyword(s):  
Particle Size ◽  
Cross Section ◽  
Coarse Aggregate ◽  
Frame Structure ◽  
Creep Coefficient ◽  
Low Viscosity ◽  
High Uniformity ◽  
Deformation Properties ◽  
Real Concentration ◽  
Mortar Matrix

Concretes with frame structure produced by using the technology of separate concreting by immersing a coarse aggregate in a low-viscosity mortar matrix due to an increased concentration of coarse aggregate have an increased E-modulus, reduced creep coefficient and cement volume in concrete compared to traditional vibrational compaction concretes. Production concrete using separate concreting technology by immersing a coarse aggregate in a mortar matrix with low-viscosity allows to obtain a frame structure of concrete with a concentration of coarse aggregate up to 0.7 when a voidness of coarse aggregate is equal 0.28. The real concentration of coarse aggregate in a concrete structure depends on the particle size of the coarse aggregate, the cross-section dimensions of the structure, and the reinforcement coefficient. The influence of geometric dimensions and the coefficient of reinforcement on the concentration of coarse aggregate in the concrete with frame structure is studied. The concentration of coarse aggregate decreases with the growth of the S/V modulus (S – area, m2, V – volume, m3) and the reinforcement coefficient, but the decrease in the E-modulus does not exceed 5%. Conclusion: regardless of the type of construction and reinforcement, the concrete of the frame structure must have a sufficiently high uniformity of deformation properties.

The Influence of the E-Modulus of Coarse Aggregate on the Stress-Strain Diagram of the Concrete with Frame Structure

2019 ◽  
Vol 974 ◽  
pp. 299-304
Author(s):  
G.V. Nesvetaev ◽  
Y.I. Koryanova ◽  
Elena Ivanchuk ◽  
A. Gortsevskoy
Keyword(s):  
Coarse Aggregate ◽  
Frame Structure ◽  
Strain Diagram ◽  
Stress Strain ◽  
Crushed Granite ◽  
High Level ◽  
Mortar Matrix

The stress-strain diagrams of concrete with frame structure made with content of coarse aggregate from 0.56 till 0.64 m3/m3, with crushed granite (E-modulus = 71 GPa) and crushed silica sandstone (E-modulus = 42 GPa) are shown. It is shown that the stress-strain diagram of the concrete with frame structure made with coarse aggregate with E-modulus 42 GPa is almost linear over the entire loading range. Stress-strain diagram of concrete made with coarse aggregate with E-modulus 71 GPa has three zones. It is concluded that the concentration of intrastructural stresses under loading in the concrete with frame structure with a decrease in the ratio of E-modulus of the coarse aggregate/E-modulus of the mortar matrix is decrease that is why bad decision is to use coarse aggregate with high level of E-modulus, such as crushed granite, in concrete with frame structure.

scholarly journals DETERMINATION OF CREEP PARAMETERS IN LAYERS OF BUILDING COMPOSITES/SLUOKSNIUOTŲJŲ STATYBINIŲ KOMPOZITŲ VALKŠNUMO PARAMETRŲ NUSTATYMAS

1998 ◽  
Vol 4 (2) ◽  
pp. 101-108 ◽  
Author(s):  
Gediminas Marčiukaitis
Keyword(s):  
Force Action ◽  
Building Product ◽  
Creep Coefficient ◽  
Deformation Properties ◽  
Linear Creep ◽  
Modulus Of Deformation ◽  
Composite Product ◽  
Properties Of Materials ◽  
Creep Deformations

Various composite building products consisting of layers of different physical-mechanical properties being tied rigidly together are manufactured and used in construction. In many cases such products curve, become flaky, crack and their thermo-insulating capability suffers. It occurs because deformation properties are not adjusted, different layers of such products deform differently under the load. And the deformation effects the behaviour of the whole structure. A correct adjustment of deformations can be achieved with allowance for creep of different layers and of the whole composite. Determination of creep parameters—creep coefficient and specific creep—depends on the orientation of layers in respect of the direction of force action. When layers are situated transverselly in respect of the direction of action of forces (stresses), creep parameters of composite depend on creep parameters of materials of separate layers and on relative volumes of these layers. Creep deformations of a composite can be described by equations describing creep of individual layers. Appropriate equations and formulas ((17)-(25)) are presented for determining such deformations. When layers are parallel to the direction of stresses, redistribution of these stresses between layers takes place. Compression stresses increase in a layer with higher modulus of deformation and decrease in that with lower modules. Proposed equations (37)-(42) enable to determine redistribution of stresses between layers, the main creep parameters of composite, their modulus of deformations and creep deformations themselves when strength of a composite product is reached, E(t0)=E(t)=const and stresses produce linear creep. Such loading of a composite product is the most common in practice. Presented formulas ((46), (52)) and diagrams show that it is possible to design a composite building product or material with creep parameters given in advance by means of appropriate distribution of product layers, selecting ratios between layers and properties of materials.

2D in-plane elastic waves in curved-tapered square lattice frame structure

2021 ◽  
pp. 1-12
Author(s):  
Rajan Prasad ◽  
Ajinkya Baxy ◽  
Arnab Banerjee
Keyword(s):  
Wave Propagation ◽  
Cross Section ◽  
Cross Sections ◽  
Elastic Waves ◽  
Dynamic Stiffness ◽  
Frame Structure ◽  
Square Lattice ◽  
Wave Localization ◽  
Finite Structure ◽  
Complete Bandgap

Abstract This work proposes a unique configuration of two-dimensional metamaterial lattice grid comprising of curved and tapered beams. The propagation of elastic waves in the structure is analyzed using the dynamic stiffness matrix (DSM) approach and the Floquet-Bloch theorem. The DSM for the unit cell is formulated under the extensional theory of curved beam considering the effects of shear and rotary inertia. The study considers two types of variable rectangular cross-sections, viz. single taper and double taper along the length of the beam. Further, the effect of curvature and taper on the wave propagation is analysed through the band diagram along the irreducible Brillouin zone. It is shown that a complete band gap, i.e. attenuation band in all the directions of wave propagation, in a homogeneous structure can be tailored with a suitable combination of curvature and taper. Generation of the complete bandgap is hinged upon the coupling of axial and transverse component of the lattice grid. This coupling emerges due to the presence of the curvature and further enhanced due to tapering. The double taper cross-section is shown to have wider attenuation characteristics than single taper cross-sections. Specifically, 83.36% and 63% normalized complete bandwidth is achieved for the double and single taper cross-section for a homogeneous metamaterial, respectively. Additional characteristics of the proposed metamaterial in time and frequency domain of the finite structure, vibration attenuation, wave localization in the equivalent finite structure are also studied.

Investigation of Concrete Filling Result in a New Concrete Filled Steel Tube Structure Using Concrete Visual Model

2011 ◽  
Vol 675-677 ◽  
pp. 945-948
Author(s):  
Ying Wang ◽  
Xiao Yu Wang ◽  
Jin Hua Xu
Keyword(s):  
Simulation Experiment ◽  
Coarse Aggregate ◽  
Steel Tube ◽  
Frame Structure ◽  
Compaction Rate ◽  
Visual Model ◽  
Concrete Filling ◽  
Cft Column ◽  
Beam Frame ◽  
Tube Structure

Self-compacting concrete (SCC) is employed to construct a new CFT column-CFT beam frame structure in this research. In order to further assess filling result of SCC in the long steel tube to ensure good compaction rate, a 1/4 scale column-beam subassembly made of acrylics tube and concrete visual model, in which fresh concrete is simulated through mortar phase and coarse aggregate phase, are adopted to do the simulation experiment work. The experiment result shows that good filling result is able to be obtained inside the subassembly which indicates that the new CFT column-CFT beam frame structure is possible to be constructed in the real building.

Influence of Shape of Coarse Aggregate on Performance of Open Graded Friction Course

2011 ◽  
Vol 239-242 ◽  
pp. 3266-3274
Author(s):  
Jin Xi Zhang ◽  
Chao Wang
Keyword(s):  
Wear Resistance ◽  
Bulk Density ◽  
Dynamic Stability ◽  
Cross Section ◽  
Coarse Aggregate ◽  
Void Content ◽  
Horizontal Cross Section ◽  
Important Material ◽  
Large Bulk ◽  
Open Graded Friction Course

As a new kind of pavement material, the Open Graded Friction Course (called OGFC) has many advantages, and so is rapidly popularized in China recently. However, the performance of OGFC decreases with the utilization of road, such as the decrease in permeability, durability and so on. In the present study, the influence of the shape of coarse aggregate, which is the most important material in OGFC, on the performance of OGFC was investigated in laboratory. The shape of coarse aggregate is indicated by the bulk density and total 4 kinds of aggregates with different bulk density were produced artificially and tested in this study. When the shape of coarse aggregate changed, the wear resistance and dynamic stability of OGFC also changed lightly. The bulk density of aggregate has no serious influence on the void content, but has obvious influence on the permeability of OGFC. The shape of continuous void in horizontal cross-section becomes rounder when the aggregate with large bulk density is used. The rounder continuous void is benefit for the flowing of water, so the permeability of OGFC is improved.

High Uniformity of ZnO Nanoparticles Synthesized by Surfactant-Assisted Solvothermal Technique

2015 ◽  
Vol 1131 ◽  
pp. 43-48 ◽  
Author(s):  
Atthaphon Maneedaeng
Keyword(s):  
Particle Size ◽  
Zno Nanoparticles ◽  
Colloidal Particles ◽  
Hydrothermal Reaction ◽  
Solvothermal Reaction ◽  
Exciton Peak ◽  
Solvothermal Technique ◽  
Tauc Plot ◽  
High Uniformity ◽  
Surfactant Assisted

The aim of this study is to develop the synthetic procedure of Zinc Oxide (ZnO) nanoparticles by using surfactant-assisted solvothermal technique in order to produce highly uniform nanosize of ZnO particles. The solvothermal reaction evidently produces smaller ZnO particle sizes compared with those obtained from hydrothermal reaction. The zwitterionic surfactant is employed in this work and it typically works well under extremely conditions i.e. high pH levels, strong electrolytes, and high temperature. The key success of surfactant utilization in the solvothermal reaction is to create reversed micelles which act as nanoreactors or templates. Because micelle consist of polar cores that may occupy a finite amount of water forming a water pool for ZnO nanomaterial synthesis. Synthesized ZnO nanoparticles were obtained from solvothermal reaction at 180°C and 18 hours in a hydrothermal reactor. The ZnO colloidal particles were separated by paper filter and cellulose nitrate membrane, respectively. The XRD pattern shows that the structure of the synthesized ZnO nanoparticles is hexagonal wurtzite and the use of surfactant does not interfere the crystal growth and structure. The particle size distribution reveals a high uniform ZnO nanoparticles obtained via this method. The UV absorption spectrum of ZnO nanoparticles synthesized by this method presents exciton peak at approximate value of 365 nanometers. The energy band gap determined by Tauc plot is 3.31 eV. Moreover, TEM images confirm the particle size consistency showing the morphology of the prepared ZnO nanoparticles.

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