scholarly journals Tensile Performance, Lap-Splice Length and Behavior of Concretes Confined by Prefabricated C-FRCM System

2021 ◽  
Vol 15 (1) ◽  
Author(s):  
Donguk Choi ◽  
Sorrasak Vachirapanyakun ◽  
Munckhtuvshin Ochirbud ◽  
Undram Naidangjav ◽  
Sangsu Ha ◽  
...  
Keyword(s):  
Uniaxial Compression ◽  
Plain Concrete ◽  
Tensile Tests ◽  
Fine Aggregate ◽  
Compression Tests ◽  
Carbon Fabric ◽  
Direct Tension ◽  
Lap Splice ◽  
Nominal Strength ◽  
Tensile Performance

AbstractResults of an experimental study aimed to evaluate tensile performance, lap-splice length of carbon fabric-reinforced cementitious matrix system (C-FRCM), and performance of concretes confined by C-FRCM are presented. Green high-strength mortar was used in this study which actively utilized recycled fine aggregate and fine waste glass powder to partially substitute cementitious binder. Test plans were developed in due consideration of prefabricated C-FRCM for strengthening concrete columns: 14 tensile tests, 12 lap-splice tests, and 6 uniaxial compression tests of plain concrete specimens confined by C-FRCM were performed. Test variable for the tensile test was number of fabric layers (one or two layers). Nominal strength of the C-FRCM with two fabric layers was 11.0 MPa while it was 7.4 MPa with one fabric layer in tension. Full strength of the carbon fabric was developed in all tensile tests while the C-FRCM with two fabric layers (with axial fiber amount = 0.59% by vol.) showed pseudo-ductile behavior. From the lap-splice tests in direct tension, an increased lap-splice length was required for the double fabrics over that for the single fabrics. The required splice length was about 170 mm for the single fabrics and it was about 310 mm for the double fabrics. Plain concrete cylinders and prismatic specimens were laterally confined by C-FRCM and subjected to uniaxial compression. All test results showed strain-softening behavior. Compressive strength increased by 10–41% while ductility also increased by 6–45% indicating applicability of the prefabricated type C-FRCM in the future.

A Novel Compression Tester for Detecting Anisotropy in Very Soft Biological Tissues

2012 ◽  
Author(s):  
Roy Wang ◽  
Rudolph L. Gleason
Keyword(s):  
Adipose Tissue ◽  
Mechanical Behavior ◽  
Uniaxial Compression ◽  
Material Properties ◽  
Soft Tissues ◽  
Tensile Tests ◽  
Biological Tissues ◽  
Compression Tests ◽  
Anisotropic Behavior ◽  
Soft Biological Tissues

Quantifying the mechanical behavior of very soft tissues (VST) is important when studying responses to injury or designing therapeutic devices; fat, brain, or liver being examples of such tissues. VST can have poor suture retention or clamp holding strength, making tensile tests difficult. As a result, uniaxial compression tests are typically the preferred choice to quantify the mechanical behavior. In these tests, isotropy is generally assumed and measuring the deformation in only one direction is needed if the material is considered incompressible [13]. In this study we present a novel testing apparatus for use on VST under uniaxial compression that can detect anisotropic behavior of the tissue if present. We validate the tester using cardiac adipose tissue and isotropic rubber as the control. Understanding the directional behavior of the tissue is important since anisotropy would require testing in multiple directions to fully characterize the material properties.

scholarly journals Study the Fire Resistance of Desert Sand Concrete (DSC) with Interface Phase through Uniaxial Compression Tests and Analyses

2021 ◽  
Vol 2021 ◽  
pp. 1-21
Author(s):  
Qian Zhang ◽  
Haifeng Liu ◽  
Qiang Liu ◽  
Jialing Che ◽  
Weiwu Yang ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Elevated Temperature ◽  
Constitutive Model ◽  
Uniaxial Compression ◽  
Fire Resistance ◽  
Elevated Temperatures ◽  
Fine Aggregate ◽  
Compression Tests ◽  
Desert Sand ◽  
Simulation Results

The shortage of sand resources and high-rise building fires are becoming increasingly prominent. Desert sand (DS) with smaller particles can effectively fill the concrete voids and further improve its working performance; it is used as a fine aggregate to produce concrete. This article studied the performance of desert sand concrete (DSC) against fire resistance by using mathematical modeling for simulation. The stress-strain curves of desert sand mortar (DSM) after elevated temperatures were tested, and the constitutive model was established. By comparing the experiment and simulation results, it was verified that the model is suitable to be adopted in this study. Data from experiment and past literature can serve as parameters for the subsequent simulation. The destruction process of DSC under uniaxial compression after elevated temperature was simulated by using ANSYS. The simulation results indicated that, after elevated temperature, compressive strength reduced with increase of interface thickness. The compressive strength of DSC had a substantially linear increase as the interface compressive strength increased. For two-grade coarse aggregate, the optimum volume content was 45%, and particle size of it showed a significant effect on the compressive strength of DSC. The DSM constitutive model and simulation results can provide a sound theoretical basis and technical support for DSC engineering applications.

scholarly journals Study on the Bending and Joint Performances of Reinforced Concrete Beams Using High-Strength Rebars

2021 ◽  
Vol 13 (6) ◽  
pp. 3482
Author(s):  
Seoungho Cho ◽  
Myungkwan Lim ◽  
Changhee Lee
Keyword(s):  
Yield Strength ◽  
High Strength ◽  
Reinforced Concrete Beams ◽  
High Yield ◽  
Performance Tests ◽  
Reinforcing Bars ◽  
Joint Performance ◽  
Lap Splice ◽  
Reinforcing Bar ◽  
Nominal Strength

High-strength reinforcing bars have high yield strengths. It is possible to reduce the number of reinforcing bars placed in a building. Accordingly, as the amount of reinforcement decreases, the spacing of reinforcing bars increases, workability improves, and the construction period shortens. To evaluate the structural performance of high-strength reinforcing bars and the joint performance of high-strength threaded reinforcing bars, flexural performance tests were performed in this study on 12 beam members with the compressive strength of concrete, the yield strength of the tensile reinforcing bars, and the tensile reinforcing bar ratio as variables. The yield strengths of the tensile reinforcement and joint methods were used as variables, and joint performance tests were performed for six beam members. Based on this study, the foundation for using high-strength reinforcing bars with a design standard yield strength equal to 600 MPa was established. Accordingly, mechanical joints of high-strength threaded reinforcing bars (600 and 670 MPa) can be used. All six specimens were destroyed under more than the expected nominal strength. Lap splice caused brittle fractures because it was not reinforced in stirrup. Increases of 21% to 47% in the loads of specimens using a coupler and a lock nut were observed. Shape yield represents destruction—a section must ensure sufficient ductility after yielding. Therefore, a coupler and lock nut are effective.

scholarly journals Investigation of Microcrack Propagation and Energy Evolution in Brittle Rocks Based on the Voronoi Model

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2108
Author(s):  
Guanlin Liu ◽  
Youliang Chen ◽  
Xi Du ◽  
Peng Xiao ◽  
Shaoming Liao ◽  
...  
Keyword(s):  
Uniaxial Compression ◽  
Damage Evolution ◽  
Rock Sample ◽  
Rock Fracture ◽  
Damage Threshold ◽  
Crack Development ◽  
Energy Evolution ◽  
Shear Cracks ◽  
Compression Tests ◽  
Microcrack Propagation

The cracking of rock mass under compression is the main factor causing structural failure. Therefore, it is very crucial to establish a rock damage evolution model to investigate the crack development process and reveal the failure and instability mechanism of rock under load. In this study, four different strength types of rock samples from hard to weak were selected, and the Voronoi method was used to perform and analyze uniaxial compression tests and the fracture process. The change characteristics of the number, angle, and length of cracks in the process of rock failure and instability were obtained. Three laws of crack development, damage evolution, and energy evolution were analyzed. The main conclusions are as follows. (1) The rock’s initial damage is mainly caused by tensile cracks, and the rapid growth of shear cracks after exceeding the damage threshold indicates that the rock is about to be a failure. The development of micro-cracks is mainly concentrated on the diagonal of the rock sample and gradually expands to the middle along the two ends of the diagonal. (2) The identification point of failure precursor information in Acoustic Emission (AE) can effectively provide a safety warning for the development of rock fracture. (3) The uniaxial compression damage constitutive equation of the rock sample with the crack length as the parameter is established, which can better reflect the damage evolution characteristics of the rock sample. (4) Tensile crack requires low energy consumption and energy dispersion is not concentrated. The damage is not apparent. Shear cracks are concentrated and consume a large amount of energy, resulting in strong damage and making it easy to form macro-cracks.

scholarly journals Design and characterization of concrete masonry parts and structural concrete using repurposed plastics as aggregate

2019 ◽  
Vol 28 (1) ◽  
pp. 81-88
Author(s):  
Miguel A. González-Montijo ◽  
Hildélix Soto-Toro ◽  
Cristian Rivera-Pérez ◽  
Silvia Esteves-Klomsingh ◽  
Oscar Marcelo Suárez
Keyword(s):  
Structural Strength ◽  
Construction Materials ◽  
Tensile Tests ◽  
Compression Tests ◽  
Conventional Concrete ◽  
Structural Capacity ◽  
Plastic Type ◽  
Concrete Mix ◽  
Scientists And Engineers

AbstractHistorically known for being one of the major pollutants in the world, the construction industry, always in constant advancement and development, is currently evolving towards more environmentally friendly technologies and methods. Scientists and engineers seek to develop and implement green alternatives to conventional construction materials. One of these alternatives is to introduce an abundant, hard to recycle, material that could serve as a partial aggregate replacement in masonry bricks or even in a more conventional concrete mixture. The present work studied the use of 3 different types of repurposed plastics with different constitutions and particle size distribution. Accordingly, several brick and concrete mix designs were developed to determine the practicality of using these plastics as partial aggregate replacements. After establishing proper working material ratios for each brick and concrete mix, compression tests as well as tensile tests for the concrete mixes helped determine the structural capacity of both applications. Presented results proved that structural strength can indeed be reached in a masonry unit, using up to a 43% in volume of plastic. Furthermore, a workable structural strength for concrete can be achieved at fourteen days of curing, using up to a 50% aggregate replacement. A straightforward cost assessment for brick production was produced as well as various empirical observations and recommendations concerning the feasibility of each repurposed plastic type examined.

scholarly journals Quantitative 3D imaging of partially saturated granular materials under uniaxial compression

2021 ◽  
Author(s):  
Marius Milatz ◽  
Nicole Hüsener ◽  
Edward Andò ◽  
Gioacchino Viggiani ◽  
Jürgen Grabe
Keyword(s):  
Granular Materials ◽  
Uniaxial Compression ◽  
Water Clusters ◽  
Local Strain ◽  
Confining Pressure ◽  
Mechanical Effect ◽  
Compression Tests ◽  
Initial Water ◽  
Interfacial Areas ◽  
Membrane Effects

AbstractGauging the mechanical effect of partial saturation in granular materials is experimentally challenging due to the very low suctions resulting from large pores. To this end, a uniaxial (zero radial stress) compression test may be preferable to a triaxial one where confining pressure and membrane effects may erase the contribution of this small suction; however, volume changes are challenging to measure. This work resolves this limitation by using X-ray imaging during in situ uniaxial compression tests on Hamburg Sand and glass beads at three different initial water contents, allowing a suction-dependent dilation to be brought to the light. The acquired tomography volumes also allow the development of air–water and solid–water interfacial areas, water clusters and local strain fields to be measured at the grain scale. These measurements are used to characterise pertinent micro-scale quantities during shearing and to relate them to the measured macroscopic response. The new and well-controlled data acquired during this experimental campaign are hopefully a useful contribution to the modelling efforts—to this end they are shared with the community.

Failure Process of Rock Sample Observed by AE Source Locating Technique under Uniaxial Compression

2006 ◽  
Vol 324-325 ◽  
pp. 567-570
Author(s):  
Yuan Hui Li ◽  
Rui Fu Yuan ◽  
Xing Dong Zhao
Keyword(s):  
Uniaxial Compression ◽  
High Speed ◽  
Failure Process ◽  
Compression Tests ◽  
Temporal And Spatial Distribution ◽  
Primary Stage ◽  
Brewing Process ◽  
Ae Signal ◽  
Failure Location ◽  
Low Amplitude

A series of uniaxial-compression tests were conducted on some representative brittle rock specimens, such as granite, marble and dolerite. A multi-channel, high-speed AE signal acquiring and analyzing system was employed to acquire and record the characteristics of AE events and demonstrate the temporal and spatial distribution of these events during the rupture-brewing process. The test result showed that in the primary stage, many low amplitude AE events were developed rapidly and distributed randomly throughout the entire specimens. In the second stage, the number of AE increased much slower than that in the first stage, while the amplitude of most AE events became greater. Contrarily to the primary stage, AE events clustered in the middle area of the specimen and distributed vertically conformed to the orientation of compression. The most distinct characteristic of this stage was a vacant gap formed approximately in the central part of the specimen. In the last stage, the number of AE events increased sharply and their magnitude increased accordingly. The final failure location coincidently inhabited the aforementioned gap. The main conclusion is that most macrocracks are developed from the surrounding microcracks existed earlier and their positions occupy the earlier formed gaps, and the AE activity usually becomes quite acute before the main rupture occurs.

Experimental-Numerical Characterization of Ordinary Concrete at the Meso-Scale

2021 ◽  
Author(s):  
GIANLUCA MAZZUCCO ◽  
Beatrice Pomaro ◽  
Giovanna Xotta ◽  
Enrico Garbin ◽  
Valentina Salomoni ◽  
...  
Keyword(s):  
Yield Criterion ◽  
Plain Concrete ◽  
Point Of View ◽  
Good Prediction ◽  
Deformation Capacity ◽  
Compression Tests ◽  
Fe Method ◽  
Stress States ◽  
Meso Scale

Modeling the post-peak behaviour of brittle materials like concrete is still a challenge from the point of view of computational mechanics, due to the strong nonlinearities arising in the material behaviour during softening and the complexity of the yield criterion that may describe their deformation capacity in generic triaxial stress states. A numerical model for plain concrete in compression is formulated within the framework of the coupled elasto-plastic-damage theory. The aim is to simulate via the Finite Element (FE) method the stress-strain behaviour of concrete at the meso-scale, where local confinement effects generally characterize the cement paste under the action of the surrounding aggregates. The mechanical characterization of the components are accomplished through a specific experimental campaign. With the subsequent validation study, it is shown that a few calibration parameters give a good prediction of load strength and deformation capacity coming from real uniaxial compression tests.

Determination of precompression stress from uniaxial compression tests

2008 ◽  
Vol 98 (1) ◽  
pp. 17-26 ◽  
Author(s):  
Karina Maria Vieira Cavalieri ◽  
Johan Arvidsson ◽  
Alvaro Pires da Silva ◽  
Thomas Keller
Keyword(s):  
Uniaxial Compression ◽  
Compression Tests ◽  
Precompression Stress
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