Uniaxial Stress-Strain Model for Concrete Confined by Rectangular Steel Tubes

2010 ◽  
Vol 163-167 ◽  
pp. 1005-1011
Author(s):  
Yue Ling Long ◽  
Jian Cai
Keyword(s):  
Triaxial Compression ◽  
Uniaxial Stress ◽  
Failure Criteria ◽  
Steel Tube ◽  
Test Results ◽  
Stress Strain ◽  
Steel Tubes ◽  
Concrete Core ◽  
Strain Behavior ◽  
The Difference

This paper presents a new model for uniaxial stress-strain relationship of concrete confined by rectangular steel tubes. The difference between concrete confinement effect provided by broad faces and that provided by narrow faces of steel tube is considered in the proposed model. The failure criteria for concrete subjected to triaxial compression is applied to estimate the ultimate strength of concrete core. The parameters of the model are determined based on the test results and the calculation of complete load-stress relationship curves is conducted for axially loaded rectangular CFT specimens using the model proposed in the paper. The concrete core strength and stress-strain behavior of rectangular CFT columns is found to exhibit good agreement with test results.

scholarly journals Proposed Model for Stress-strain Behavior of Fly Ash Concrete Under the Freezing and Thawing Cycles

2020 ◽  
Author(s):  
Ali Hemmati ◽  
Heydar Arab
Keyword(s):  
Fly Ash ◽  
Numerical Models ◽  
Test Results ◽  
Freezing And Thawing ◽  
Stress Strain ◽  
Strain Behavior ◽  
Fly Ash Concrete ◽  
Proposed Model ◽  
The Difference ◽  
Freezing And Thawing Cycles

Fly ash is a supplementary cement material using instead of Portland cement in concrete. Using this material concludes to less emission of greenhouse gas and less water demand of concrete. In this paper, an experimental investigation was carried out on compressive stress–strain behavior of three groups of concrete specimens with different water/cement ratios (0.45, 0.5 and 0.55), containing 0, 10, 20, 30 and 40 percent of fly ash (by weight), after subjecting to freezing and thawing cycles. 0, 45, 100 and 150 cycles of freezing and thawing were applied on these specimens according to ASTM C666 and the results presented. Numerical models for the stress–strain behavior of these frozen-thawed concrete were developed and compared with the available experimental data. Results show that the maximum compressive strength of these concrete specimens exposing cycles of freezing and thawing is gained by using about 10 % of fly ash. Moreover, there is a good agreement between the proposed models and test results and the difference is less than 5 %.

Three Types of Stress-Strain Relationship’s Comparison of Circular Tubed Reinforced Concrete in FEA

2012 ◽  
Vol 204-208 ◽  
pp. 930-933
Author(s):  
Xiao Hu ◽  
Zhen Lin Chen
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Uniaxial Stress ◽  
Steel Tube ◽  
Finite Element Analyses ◽  
Stress Strain ◽  
Concrete Filled Steel Tube ◽  
Bearing Analysis

The paper introduces 3 types of uniaxial stress-strain relationships of concrete filled steel tube by Pan Youguang, Susantha and Saenz, and performs finite element analyses of the axial strengths of 18 CTRC columns, studies the characters of three models, and comprises between the axial strengths from FEA and existed experiments. Results show these 3 types of model are all suitable for bearing analysis, but Pan’s model is more accurate.

Research on Hydraulic Conductivity of Coarse Sandstone under Triaxial Compression

2011 ◽  
Vol 94-96 ◽  
pp. 1146-1151 ◽  
Author(s):  
Guan Rong ◽  
Xiao Jiang Wang
Keyword(s):  
Hydraulic Conductivity ◽  
Circumferential Strain ◽  
Triaxial Compression ◽  
Confining Pressure ◽  
Test Results ◽  
Stress Strain ◽  
Deformation And Failure ◽  
Maximum Value ◽  
Strain Process ◽  
Peak Value

Permeability test for complete stress-strain process of coarse sandstone were carried out in triaxial test instrument. On the basis of test results, the influence of confining pressure and strain on the hydraulic conductivity was discussed. It is shown that in the complete stress-strain process, hydraulic conductivity changes in the law that presents the same character with the curve of stress-strain. The hydraulic conductivity reduces slightly with the increase of deviatoric stress in the stage of micro fracture compressing and elastic; In the elastoplastic stage, along with the expansion of new fractures, the hydraulic conductivity increases slowly at first and then reaches sharply to the maximum value after peak point; In the post-peak stage, the fracture which controls the hydraulic conductivity of coarse sandstone is compressed because of the confining pressure and the hydraulic conductivity decreases. During the process of deformation and failure, the hydraulic conductivity is more sensitive to the change of circumferential strain. With the increase of confining pressure, the increased value from initial to peak value and the decreased value from peak to residual value decreases.

scholarly journals Analytical Model for Restraint Strains and Self-stressed in Expansive Concrete Filled Steel Tubes (ECFST) estimation

2020 ◽  
pp. 93-98
Author(s):  
Viktar V. Tur ◽  
Radoslaw Duda ◽  
Dina Khmaruk ◽  
Viktar Basav
Keyword(s):  
Experimental Data ◽  
Experimental Studies ◽  
Steel Tube ◽  
Development Model ◽  
Steel Tubes ◽  
Concrete Core ◽  
Expansive Concrete ◽  
Proposed Model ◽  
Comparison Results ◽  
Concrete Filled Steel Tubes

In this paper, a modified strains development model (MSDM) for expansive concrete-filled steel tube (ECFST) was formulated and verified on the experimental data, obtained from testing specimens on the expansion stage. The modified strain development model for restraint strains and self-stresses values estimation in concrete with high expansion energy capacity under any type of the symmetrical and unsymmetrical finite stiffness restraint conditions was proposed. Based on proposed MSDM a new model for expansive concrete-filled steel tubes is developed. The main difference between this model and other previously developed models consists in taking into account in the basic equations an induced force in restrain that is considered as an external load applied to the concrete core of the member. For verification of the proposed model-specific experimental studies were performed. As follows from comparison results restrained expansion strains values calculated following the proposed model shows good compliance with experimental data. The values predicted by the proposed MSDM for concrete-filled steel and obtained experimental data demonstrated good agreement that confirms the validity of the former.

scholarly journals Failure Criteria and Constitutive Relationship of Lightweight Aggregate Concrete under Triaxial Compression

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 507
Author(s):  
Peihuan Ye ◽  
Yuliang Chen ◽  
Zongping Chen ◽  
Jinjun Xu ◽  
Huiqin Wu
Keyword(s):  
Triaxial Compression ◽  
Lightweight Aggregate ◽  
Confining Pressure ◽  
Failure Criteria ◽  
Constitutive Relationship ◽  
Lightweight Aggregate Concrete ◽  
Stress Strain ◽  
Aggregate Concrete ◽  
Stress Theory ◽  
Relationship Of

This paper investigates the compression behavior and failure criteria of lightweight aggregate concrete (LAC) under triaxial loading. A total of 156 specimens were tested for three parameters: concrete strength, lateral confining pressure and aggregate immersion time, and their effects on the failure mode of LAC and the triaxial stress-strain relationship of LAC is studied. The research indicated that, as the lateral constraint of the specimen increases, the failure patterns change from vertical splitting failure to oblique shearing failure and then to indistinct traces of damage. The stress-strain curve of LAC specimens has an obvious stress plateau, and the curve no longer appears downward when the confining pressure exceeds 12 MPa. According to the experimental phenomenon and test data, the failure criterion was examined on the Mohr–Coulomb theory, octahedral shear stress theory and Rendulic plane stress theory, which well reflects the behavior of LAC under triaxial compression. For the convenience of analysis and application, the stress-strain constitutive models of LAC under triaxial compression are recommended, and these models correlate well with the test results.

scholarly journals Triaxial Testing of Geosynthetics Reinforced Tailings with Different Reinforced Layers

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1943
Author(s):  
Fu Yi ◽  
Changbo Du
Keyword(s):  
Triaxial Compression ◽  
Friction Angle ◽  
Confining Pressure ◽  
Test Results ◽  
Compression Tests ◽  
Strength Index ◽  
Stress Strain ◽  
High Confining Pressure ◽  
Zhang Model ◽  
Triaxial Compression Tests

To evaluate the shear properties of geotextile-reinforced tailings, triaxial compression tests were performed on geogrids and geotextiles with zero, one, two, and four reinforced layers. The stress–strain characteristics and reinforcement effects of the reinforced tailings with different layers were analyzed. According to the test results, the geogrid stress–strain curves show hardening characteristics, whereas the geotextile stress–strain curves have strain-softening properties. With more reinforced layers, the hardening or softening characteristics become more prominent. We demonstrate that the stress–strain curves of geogrids and geotextile reinforced tailings under different reinforced layers can be fitted by the Duncan–Zhang model, which indicates that the pseudo-cohesion of shear strength index increases linearly whereas the friction angle remains primarily unchanged with the increase in reinforced layers. In addition, we observed that, although the strength of the reinforced tailings increases substantially, the reinforcement effect is more significant at a low confining pressure than at a high confining pressure. On the contrary, the triaxial specimen strength decreases with the increase in the number of reinforced layers. Our findings can provide valuable input toward the design and application of reinforced engineering.

Elastomer Behavior IV. Loop Structure of Elastomer Networks

1966 ◽  
Vol 39 (5) ◽  
pp. 1489-1495
Author(s):  
L. C. Case ◽  
R. V. Wargin
Keyword(s):  
Experimental Data ◽  
Crosslink Density ◽  
Strain Curve ◽  
Uniaxial Stress ◽  
Polymer Chains ◽  
Theoretical Treatment ◽  
Loop Structure ◽  
Stress Strain ◽  
Strain Behavior ◽  
Selection Of

Abstract A new theoretical treatment strongly indicates that an elastomer network actually consists of a system of fused, closed, interpenetrating loops of polymer chains. This interpenetrating loop structure restricts the movement of the chains and thereby affects the stress-strain behavior of the elastomer. Methods have been developed to enable the calculation of the number of effective crosslinks caused by loop interpenetrations (virtual crosslinks). The uniaxial stress-strain behavior of an elastomer predicted using our methods can be fitted almost perfectly to published experimental data by proper selection of chain parameters. Previous theoretical treatments gave only a qualitative fit to the experimental data for the stress-strain behavior of elastomers and were not capable of predicting the correct shape of the experimental stress-strain curve. The present treatment gives a nearly perfect fit for both stress as a function of strain at constant crosslink density, and stress as a function of crosslink density at constant strain, and thus represents a vast improvement.

Theoretical Study on Axial Capacity of CFRP Reinforced Self-Stressing Concrete Filled Steel Tubes

2011 ◽  
Vol 121-126 ◽  
pp. 3025-3029
Author(s):  
Hui Li ◽  
Jun Deng ◽  
Jun Hong Lin
Keyword(s):  
Theoretical Study ◽  
Steel Tube ◽  
Limit States ◽  
Steel Tubes ◽  
Concrete Core ◽  
Cfrp Sheets ◽  
Axial Capacity ◽  
Ultimate Equilibrium ◽  
Concrete Filled Steel Tubes ◽  
Cfrp Wrapping

Since the expansion of the cement during curing was constraint by the steel tube, the concrete core in the self-stressing concrete-filled steel tubes (SSCFST) is under tri-axially compression before applying load, which increases the axial capacity of the SSCFST. In addition, Carbon fiber reinforced polymer (CFRP) wrapping can avoid bucking of the steel tube, increase the axial capacity and improve the durability of SSCFST. This study presents a theoretical study on axial capacity of the SSCFST wrapped with CFRP sheets. Several basic assumptions are proposed. The ultimate equilibrium method was employed to analyze the axial capacity, of which two limit states, including steel tube bucking and CFRP sheets rupturing were considered. The analytical results from an example show that the initial self-stress improves axial capacity of the SSCFST by about 30% and the CFRP reinforcement improves axial capacity by about 15%.

A Simple and Practicable Approach on Implementing for the Reduced Triaxial Extension by the Conventional Triaxial Apparatus

2011 ◽  
Vol 250-253 ◽  
pp. 2089-2092
Author(s):  
Rong Jian Li ◽  
Xi An Li ◽  
Gao Feng Che ◽  
Wen Zheng ◽  
Wen Jun Chen
Keyword(s):  
Triaxial Compression ◽  
Stress Path ◽  
Test Results ◽  
Triaxial Apparatus ◽  
Eolian Sand ◽  
Conventional Triaxial Compression ◽  
The Difference ◽  
Shear Behaviors ◽  
The Impact ◽  
Triaxial Extension

Stress path is one of the very important factors of soil strength. It is significant to study the strength and reveal the importance of the impact of sand in different stress path conditions. Firstly, an ameliorating approach on implementing for the reduced triaxial extension by the conventional triaxial apparatus was discussed. Then, In order to study shear behaviors of the eolian sand under different stress path, two monotonic shearing tests with the conventional triaxial compression and the reduced triaxial extension stress path were performed and analyzed. The test results not only indicate that the amelioration on conventional triaxial apparatus is simple, practicable and inexpensive, but also reveal the difference of strength’s parameter between the reduced triaxial extension and conventional triaxial compression stress path. In sum, the stress path has important effect on the strength of the eolian sand.

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