Stress-Strain Model for Confined Concrete in Cross-Shaped Columns

To establish complete stress-strain curve equations for confined concrete in cross-shaped columns, we designed 7 test specimens corresponding to the usable eigenvalue range of stirrup of the cross-shaped columns. We obtained the test results of the reinforced concrete cross-shaped columns through axial compression test, got the system parameters of a stress-strain model through statistical analysis of the test data, and then established stress-strain curves for confined concrete in the cross-shaped columns. This model reflects the variation rule of the stress-strain curve of confined concrete in cross-shaped columns. Compared with the stress-strain model for confined concrete in square columns, the confined concrete in cross-shaped columns has smaller peak stress, larger peak strain, and relatively steeper descending part of curve. The research results provide theorotical basis for nonlinear analysis of cross-shaped columns.

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A Stress-Strain Model for Brick Prism under Uniaxial Compression

Advances in Civil Engineering ◽

10.1155/2019/7682575 ◽

2019 ◽

Vol 2019 ◽

pp. 1-10 ◽

Cited By ~ 2

Author(s):

Keun-Hyeok Yang ◽

Yongjei Lee ◽

Yong-Ha Hwang

Keyword(s):

Strain Curve ◽

Peak Stress ◽

Test Results ◽

Compression Tests ◽

Stress Strain Curve ◽

Stress Strain ◽

Proposed Model ◽

Relationship Model ◽

Strain Relationship ◽

Strain Model

This study proposes a simple and rational stress-strain relationship model applicable to brick masonry under compression. The brick prism compression tests were conducted with different mortar strengths and with constant brick strength. From the observation of the test results, shape of the stress-strain curve is assumed to be parabola. In developing the stress-strain model, the modulus of elasticity, the strain at peak stress, and the strain at 50% of the peak stress on the descending branch were formulated from regression analysis using test data. Numerical and statistical analyses were then performed to derive equations for the key parameter to determine the slopes at the ascending and descending branches of the stress-strain curve shape. The reliability of the proposed model was examined by comparisons with actual stress-strain curves obtained from the tests and the existing model. The proposed model in this study turned out to be more accurate and easier to handle than previous models so that it is expected to contribute towards the mathematical simplicity of analytical modeling.

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Dynamic Characteristics of Sandstone under Coupled Static-Dynamic Loads after Freeze-Thaw Cycles

Applied Sciences ◽

10.3390/app10103351 ◽

2020 ◽

Vol 10 (10) ◽

pp. 3351

Author(s):

Bo Ke ◽

Jian Zhang ◽

Hongwei Deng ◽

Xiangru Yang

Keyword(s):

Energy Absorption ◽

Dynamic Characteristics ◽

Shear Failure ◽

Strain Curve ◽

Peak Stress ◽

Peak Strain ◽

Compression Stress ◽

Stress Strain Curve ◽

Stress Strain ◽

Freeze Thaw

The effect of temperature fluctuation on rocks needs to be considered in many civil engineering applications. Up to date the dynamic characteristics of rock under freeze-thaw cycles are still not quite clearly understood. In this study, the dynamic mechanical properties of sandstone under pre-compression stress and freeze-thaw cycles were investigated. At the same number of freeze-thaw cycles, with increasing axial pre-compression stress, the dynamic Young’s modulus and peak stress first increase and then decrease, whereas the dynamic peak strain first decreases and then increases. At the same pre-compression stress, with increasing number of freeze-thaw cycles, the peak stress decreases while the peak strain increases, and the peak strain and peak stress show an inverse correlation before or after the pre-compression stress reaches the densification load of the static stress–strain curve. The peak stress and strain both increase under the static load near the yielding stage threshold of the static stress–strain curve. The failure mode is mainly shear failure, and with increasing axial pre-compression stress, the degree of shear failure increases, the energy absorption rate of the specimen increases first and then decreases. With increasing number of freeze-thaw cycles, the number of fragments increases and the size diminishes, and the energy absorption rates of the sandstone increase.

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Performance of Circular Concrete-Filled FRP-Grooved Steel Composite Tube Columns under Axial Compression

Polymers ◽

10.3390/polym13213638 ◽

2021 ◽

Vol 13 (21) ◽

pp. 3638

Author(s):

Kunting Miao ◽

Yang Wei ◽

Xi Zhang ◽

Kaiqi Zheng ◽

Fenghui Dong

Keyword(s):

Failure Modes ◽

Linear Part ◽

Strain Curve ◽

Peak Stress ◽

Steel Tube ◽

Peak Strain ◽

Test Results ◽

Stress Strain ◽

Composite Tube ◽

Steel Composite

A new structure termed “concrete-filled FRP-grooved steel composite tube (CFGCT) column” is proposed, which is composed of a stress-released steel tube (i.e., grooved steel tube), fiber-reinforced polymer (FRP) and concrete. Axial load tests were carried out on twenty-four specimens to investigate the constraint effect of this structure. Three main experimental variables were considered: the steel tube thickness, the FRP type, and the FRP layer. The failure modes, stress-strain relationships and the effect of the main experimental variables were discussed. The stress-strain curves of this new structure are composed of an initial linear part, a nonlinear transition part, a strengthening part and a residual part. The test results demonstrate that the bearing capacity of the structure was improved, and that the mechanical mechanism of the structure was simplified due to the stress-released grooves. Based on the test results and previous studies, formulas for calculating the ultimate stress (fcu), ultimate strain (εcu), peak stress (fcc) and peak strain (εcc) were proposed. In addition, models for predicting the stress-strain curves of CFGCT columns were put forward, and the models could precisely simulate the stress-strain curve of this new composite structure. Hence, this study indicates that a structure composed of FRP and stress-released steel tube can effectively constrain concrete.

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Stress-Strain Relationship of Ca(OH)2-Activated Hwangtoh Concrete

The Scientific World JOURNAL ◽

10.1155/2014/846805 ◽

2014 ◽

Vol 2014 ◽

pp. 1-9

Author(s):

Keun-Hyeok Yang ◽

Ju-Hyun Mun ◽

Hey-Zoo Hwang

Keyword(s):

Compressive Strength ◽

Strain Curve ◽

Peak Stress ◽

Actual Behavior ◽

Test Results ◽

Stress Strain ◽

Strain Behavior ◽

Strain Relationship ◽

Relationship Of ◽

Strain Model

This study examined the stress-strain behavior of 10 calcium hydroxide (Ca(OH)2)-activated Hwangtoh concrete mixes. The volumetric ratio of the coarse aggregate (Vagg) and the water-to-binder (W/B) ratio were selected as the main test variables. TwoW/Bratios (25% and 40%) were used and the value ofVaggvaried between 0% and 40.0%, and 0% and 46.5% forW/Bratios of 25% and 40%, respectively. The test results demonstrated that the slope of the ascending branch of the stress-strain curve of Ca(OH)2-activated Hwangtoh concrete was smaller, and it displayed a steeper drop in stress in the descending branch, compared with those of ordinary Portland cement (OPC) concrete with the same compressive strength. This trend was more pronounced with the increase in theW/Bratio and decrease inVagg. Based on the experimental observations, a simple and rational stress-strain model was established mathematically. Furthermore, the modulus of elasticity and strain at peak stress of the Ca(OH)2-activated Hwangtoh concrete were formulated as a function of its compressive strength andVagg. The proposed stress-strain model predicted the actual behavior accurately, whereas the previous models formulated using OPC concrete data were limited in their applicability to Ca(OH)2-activated Hwangtoh concrete.

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Mechanical Characteristic of Buffer/Backfilling Materials After Different Temperatures

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.347-353.852 ◽

2011 ◽

Vol 347-353 ◽

pp. 852-857

Author(s):

Ming Qing Yan ◽

Fa Cheng Yi ◽

Bao Long Zhu

Keyword(s):

Modulus Of Elasticity ◽

Temperature Increase ◽

Strain Curve ◽

Peak Stress ◽

Peak Strain ◽

Stress Strain Curve ◽

Stress Strain ◽

Different Temperatures ◽

Backfill Materials ◽

Increasing Temperature

Based on uniaxial compression test, the mechanical properties of buffer/backfilling materials after different temperatures are studied. The study analyzed buffer/backfilling materials of stress-strain curve，peak stress，modulus of elasticity，peak strain, with the variation of temperature. The buffer/backfilling materials of strengthening and degradation in different temperature are discussed briefly. The test result show that below 200°C, buffer/backfilling materials of stress-strain curve of slope，peak stress，modulus of elasticity，peak strain ,are increase with increasing temperature increase. The main reason is that with increasing temperature, adsorbed water in the sample will evaporate, and brittleness of sample will improve; mineral particles of expansion lead to the original cracks closing, the porosity will reduce, and improve friction properties between particles. 300 °C,buffer / backfill materials of stress - strain curve of slope, peak stress, elastic modulus, decreased to varying degrees compared to 200 °C. the main reason is that thermal stress damage to the internal structure of the samples, resulting in new small cracks. The peak strain of buffer / backfill materials in the 25 °C～100 °C is increase with increasing temperature increase.100°C～200°C, peak strain is decrease with the increase of temperature. In the 200 °C～300 °C, the peak strain change little.

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Experimental Study on Biaxial Dynamic Compressive Properties of ECC

Materials ◽

10.3390/ma14051257 ◽

2021 ◽

Vol 14 (5) ◽

pp. 1257

Author(s):

Shuling Gao ◽

Guanhua Hu

Keyword(s):

Strain Rate ◽

Lateral Pressure ◽

Deformation Modulus ◽

Strain Curve ◽

Peak Stress ◽

Pressure Level ◽

Strain Rates ◽

Peak Strain ◽

Stress Strain Curve ◽

Toughness Index

An improved hydraulic servo structure testing machine has been used to conduct biaxial dynamic compression tests on eight types of engineered cementitious composites (ECC) with lateral pressure levels of 0, 0.125, 0.25, 0.5, 0.7, 0.8, 0.9, 1.0 (the ratio of the compressive strength applied laterally to the static compressive strength of the specimen), and three strain rates of 10−4, 10−3 and 10−2 s−1. The failure mode, peak stress, peak strain, deformation modulus, stress-strain curve, and compressive toughness index of ECC under biaxial dynamic compressive stress state are obtained. The test results show that the lateral pressure affects the direction of ECC cracking, while the strain rate has little effect on the failure morphology of ECC. The growth of lateral pressure level and strain rate upgrades the limit failure strength and peak strain of ECC, and the small improvement is achieved in elastic modulus. A two-stage ECC biaxial failure strength standard was established, and the influence of the lateral pressure level and peak strain was quantitatively evaluated through the fitting curve of the peak stress, peak strain, and deformation modulus of ECC under various strain rates and lateral pressure levels. ECC’s compressive stress-strain curve can be divided into four stages, and a normalized biaxial dynamic ECC constitutive relationship is established. The toughness index of ECC can be increased with the increase of lateral pressure level, while the increase of strain rate can reduce the toughness index of ECC. Under the effect of biaxial dynamic load, the ultimate strength of ECC is increased higher than that of plain concrete.

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Numerical Simulation of the Effect of Temperature on the Failure Strength of Rock

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.690-693.1737 ◽

2013 ◽

Vol 690-693 ◽

pp. 1737-1740

Author(s):

Lin Bu ◽

Tao Xu ◽

Yun Jie Zhang

Keyword(s):

Mechanical Properties ◽

Rock Fracture ◽

Strain Curve ◽

Peak Stress ◽

Effect Of Temperature ◽

Peak Strain ◽

Failure Strength ◽

Stress Strain Curve ◽

Physical Tests ◽

Compression Condition

The mechanical properties of granite experiencing high temperatures under uniaxial compression condition were simulated in this paper. Numerically simulated stress-strain curve, peak stress, peak strain and the tangent elastic modulus were compared with the corresponding physical tests. Simulated results agree well with physical tests results, it is shown that Abaqus is suitable for the analysis of the temperature effect on rock fracture.

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Experimental Research on the Stress - Strain Curve of Regional Confined Concrete under Single Axial Press

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.584-586.1289 ◽

2014 ◽

Vol 584-586 ◽

pp. 1289-1292

Author(s):

Guo Liang Zhu

Keyword(s):

Mechanical Properties ◽

Theoretical Analysis ◽

Constitutive Model ◽

Theoretical Basis ◽

Strain Curve ◽

Confined Concrete ◽

Constitutive Relationship ◽

Stress Strain Curve ◽

Stress Strain ◽

Relationship Of

Regional confined concrete is base on confined concrete. It is the theory and application of a new attempt and development on confined concrete. To apply it to the actual project, we need to research mechanical properties and establish constitutive relationship of regional confined concrete. According to the research, we had carried on a series of tests, founded the stress-strain constitutive model of regional confined concrete under single axial press. The accuracy of theoretical analysis were more fully verified , and a theoretical basis for the application was provided.

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Stress-strain model study of ferrous tailing concrete short column restraint by hooping

Mining Scince ◽

10.37190/msc192616 ◽

2019 ◽

Vol 26 ◽

Author(s):

Sujuan Li ◽

Hongzhen Kang

Keyword(s):

Strain Curve ◽

Stress Strain Curve ◽

Stress Strain ◽

Natural Sand ◽

Short Column ◽

Model Study ◽

Calculation Results ◽

Strain Relationship ◽

Strain Model ◽

Curve Equation

This paper talked about stress-strain curve of stirrup restraint ferrous tailing concrete by test and theoretical analysis. Twenty short column of 5 strength grade are contained in the test with WC30, WC35, WC40, WC45 and WC50. And the stress-strain data was achieved after the axial compression behavior test. Through the stress-strain curve, it can be found that the stress-strain relationship is similar with natural sand concrete. At the same time, it was put forward the whole stress-strain curve equation of stirrup restraint ferrous tailing concrete. The calculation results showed that the data calculating by the eqution this paper are in good agreement with the experimental data.

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