scholarly journals Axial Compressive Strength of Metal Sheet Confined Concrete Cylinders Based on Various Concrete Strengths

2018 ◽  
Vol 4 (11) ◽  
pp. 2529
Author(s):  
Tanyada Pannachet ◽  
Maetee Boonpichetvong
Keyword(s):  
Compressive Strength ◽  
Concrete Strength ◽  
Metal Sheet ◽  
Confined Concrete ◽  
Axial Strength ◽  
Strength Based ◽  
Concrete Cylinders ◽  
Axial Compressive Strength ◽  
Original Strength ◽  
Strength Improvement

This paper investigated effect of concrete strength on axial strength improvement of the metal sheet confined concrete cylinders under axial compression. Totally, 27 concrete specimens were tested based on three different concrete strengths of approximately 13, 32 and 39 MPa. Epoxy was used as a bonding material along interface between concrete and metal sheet. Based on three different concrete strengths, different level of confinement was established by taking one layer and three layers of metal sheet confinement. The experimental results revealed that axial compressive strength of concrete cylinders could be improved by mean of metal sheet wrapping. It was shown that effectiveness of axial strength improvement of metal sheet confined concrete cylinders depended on original unconfined compressive strength of the core concrete. With lower concrete strength, it was found that use of metal sheet confinement could increase the original strength of the columns more effectively than the case of higher concrete strength. Based on existing results, it was observed that strength improvement prediction given by Richart et al. (1928) could be adopted conservatively with exception of very low concrete strength.

scholarly journals A Proposed Soft Computing Model for Ultimate Strength Estimation of FRP-Confined Concrete Cylinders

2020 ◽  
Vol 10 (5) ◽  
pp. 1769 ◽  
Author(s):  
Reza Kamgar ◽  
Hosein Naderpour ◽  
Houman Ebrahimpour Komeleh ◽  
Anna Jakubczyk-Gałczyńska ◽  
Robert Jankowski
Keyword(s):  
Compressive Strength ◽  
Soft Computing ◽  
Concrete Strength ◽  
Fiber Reinforced Polymer ◽  
Confined Concrete ◽  
Confinement Pressure ◽  
Reinforced Polymer ◽  
Soft Computing Techniques ◽  
Concrete Cylinders ◽  
New Formulation

In this paper, the feed-forward backpropagation neural network (FFBPNN) is used to propose a new formulation for predicting the compressive strength of fiber-reinforced polymer (FRP)-confined concrete cylinders. A set of experimental data has been considered in the analysis. The data include information about the dimensions of the concrete cylinders (diameter, length) and the total thickness of FRP layers, unconfined ultimate concrete strength, ultimate confinement pressure, ultimate tensile strength of the FRP laminates and the ultimate concrete strength of the concrete cylinders. The confined ultimate concrete strength is considered as the output data, while other parameters are considered as the input data. These parameters are mostly used in existing FRP-confined concrete models. Soft computing techniques are used to estimate the compressive strength of FRP-confined concrete cylinders. Finally, a new formulation is proposed. The results of the proposed formula are compared to the existing methods. To verify the proposed method, results are compared with other methods. The results show that the described method can forecast the compressive strength of FRP-confined concrete cylinders with high precision in comparison with the existing formulas. Moreover, the mean percentage of error for the proposed method is very low (3.49%). Furthermore, the proposed formula can estimate the ultimate compressive capacity of FRP-confined concrete cylinders with a different type of FRP and arbitrary thickness in the initial design of practical projects.

The Application of Bounded Normal Distribution in Statistics of Concrete Strength

2013 ◽  
Vol 671-674 ◽  
pp. 1641-1647
Author(s):  
Xu Yan ◽  
Yong Zhi Zuo ◽  
Qiao Zhi Lu ◽  
Da Huo ◽  
Ming Liu
Keyword(s):  
Compressive Strength ◽  
Normal Distribution ◽  
Goodness Of Fit ◽  
Concrete Strength ◽  
Concrete Compressive Strength ◽  
Mean Values ◽  
Coefficients Of Variations ◽  
Log Normal ◽  
Original Strength ◽  
Log Normal Distribution

23,037 values of concrete compressive strength from construction sites were obtained from Beijing Building Construction Research Institute from 2009-2012 by standard cubes testing method. The mean values, standard deviations, coefficients of variations, maxima and minima were derived from the original strength values analyzed and compared with the data in 1989. The results make up for the lack in C25/C30 and the maxima/minima of every strength class of concrete of the former data. Both the coefficients of variations and mean values have increased in recent years. The log-normal distribution commonly used in concrete compressive strength statistics is not that suitable for strength modeling for it is unbounded. So a bounded normal distribution was given in this paper. By Geary's test, the goodness-of-fit of bounded normal distribution is better than log-normal distribution has been proved.

scholarly journals Estimation of compressive strength based on Pull-Out bond test results for on-site concrete quality control

2011 ◽  
Vol 4 (4) ◽  
pp. 582-591 ◽  
Author(s):  
M. S. Lorrain ◽  
M. P. Barbosa ◽  
L. C. P. Silva Fº
Keyword(s):  
Quality Control ◽  
Compressive Strength ◽  
Concrete Strength ◽  
Test Results ◽  
Compression Tests ◽  
Pull Out ◽  
Underlying Principle ◽  
Strength Based ◽  
Concrete Quality ◽  
Definition Of

Quality control of structural concrete has been conducted for several decades based mainly on the results of axial compression tests. This kind of test, although widely used, is not exempt from errors and has some considerable drawbacks that may affect its reliability, such as the need for appropriate and careful specimen conditioning and adoption of adequate capping techniques. For these reasons, it would be useful to have complementary or alternative ways to check compressive strength, in order to improve concrete quality control. The use of a bond test to monitor concrete strength is being proposed by an international group of researchers from France, Tunisia and Brazil as a potential means to this end. Given the fact that the link between bond resistance and concrete strength is already well established, this type of test seems to be a viable alternative to traditional methods. Nonetheless, to check if the underlying principle is sound when used in different circumstances, the group has been gathering data from several studies conducted by different researchers in various countries, with distinct concretes and rebar types. An analysis of the data collected shows that there is a clear and strong correlation between bond resistance and compressive strength, no matter the influence of other variables. This result validates the basic idea of using an Appropriate Pull-Out (APULOT) bond test to assess concrete strength. If the general principle is valid for random data obtained from different studies, the definition of a clear and appropriate test will probably lead to the reduction of experimental noise and increase the precision of the strength estimates obtained using this method.

scholarly journals BEHAVIOUR OF HIGH-STRENGTH CONCRETE CIRCULAR COLUMNS CONFINED BY HIGH-STRENGTH SPIRALS UNDER CONCENTRIC COMPRESSION

2020 ◽  
Vol 26 (6) ◽  
pp. 564-578
Author(s):  
Chongchi Hou ◽  
Wenzhong Zheng ◽  
Wei Chang
Keyword(s):  
Compressive Strength ◽  
High Strength Concrete ◽  
Concrete Strength ◽  
High Strength ◽  
Concrete Columns ◽  
Confined Concrete ◽  
Concrete Compressive Strength ◽  
Strength Concrete ◽  
Proposed Model ◽  
High Strength Concrete Columns

This paper tested the behaviour of 32 high-strength concrete columns confined by high-strength spirals under concentric compression. The test parameters included unconfined concrete compressive strength, spiral yield strength, volumetric ratio, and spiral spacing. The results showed that bulging and shear sliding were the two characteristic types of failure patterns of the thirty-two confined columns, depending on spiral spacing and concrete strength. Moreover, the spiral in most specimens did not yield at the confined concrete compressive strength. An analytical confinement model for high-strength concrete columns confined by high-strength spirals was proposed. In this proposed model, the calculated value of the spiral stress at the confined concrete compressive strength was used to calculate the feature points of the stressstrain curve. The proposed model showed good correlations with available experimental results of 64 columns.

A constitutive model of concrete confined by steel reinforcements and steel jackets

2005 ◽  
Vol 32 (1) ◽  
pp. 279-288 ◽  
Author(s):  
Y-F Li ◽  
S-H Chen ◽  
K-C Chang ◽  
K-Y Liu
Keyword(s):  
Constitutive Model ◽  
Concrete Strength ◽  
Strain Curve ◽  
Steel Reinforcement ◽  
Confined Concrete ◽  
Stress Strain ◽  
Steel Jacket ◽  
Proposed Model ◽  
Concrete Cylinders ◽  
Different Types

In this paper, a total of 60 concrete cylinders 30 cm in diameter and 60 cm in length confined by steel jackets of different thicknesses and different types of lateral steel reinforcements are tested to obtain the stress–strain curves of the cylinders. A constitutive model is proposed to describe the behavior of concrete confined by steel reinforcement, steel jackets, and both steel reinforcement and steel jackets used to retrofit and strengthen reinforced concrete structures. The confined concrete stress–strain curve of the proposed model is divided into two regions: the curve in the first region is approximated using a second-order polynomial equation, and that in the second region using an nth-order power-law equation, where n is a function of the unconfined concrete strength and the lateral confining stress. The results of the experiments show that different types of lateral steel reinforcement contribute greatly to the compressive strength of concrete cylinders confined by the reinforcement. Comparing the stress–strain curves of the uniaxial test with that from the proposed model, we conclude that the proposed model for concrete confined by a steel jacket and lateral steel reinforcement can predict the experimental results very well.Key words: constitutive model, steel jacket, confined concrete.

Research on Cross-Sectional Area Converting Principle Based Model of FRP Confined Concrete Axial Compressive Strength

2011 ◽  
Vol 243-249 ◽  
pp. 5541-5546
Author(s):  
Tian Zhi Zhu ◽  
Ming Zhang ◽  
Yan Ying Dong
Keyword(s):  
Compressive Strength ◽  
Computational Model ◽  
Ultimate Strength ◽  
Cross Sectional Area ◽  
Confined Concrete ◽  
Sectional Area ◽  
Cross Sectional ◽  
Column Section ◽  
Cylindrical Column ◽  
Axial Compressive Strength

Fiber reinforced plastics (FRP) has been widely used in structure reinforcement processing. It is a comparatively mature field in computational models of cylindrical axial compressive strength on FRP confined concrete. In this paper, we conduct a possessive analysis on the axial compressive property that is based on the cylindrical stress model of FRP confined concrete, considering the difference among square column section, rectangular column and cylindrical column. Meanwhile, based on cross-sectional area and moment of inertia equivalent principles, we propose an equivalent diameter formula for converting rectangular column section into cylindrical column section. We also introduce sectional influence coefficients to modify ultimate strength and establish a model of ultimate strength for FRP confined concrete. Furthermore, we use the existing experimental data to test the validity and feasibility of the model. Experimental Results of the computational model are quite coincident and consistent with the tests. Computational model can reflect the true characteristics of FRP confined concrete. Therefore, the models proposed in this paper are significant in the practice of construction project.

Experimental Study on Compressive Behavior of CFRP Confined Concrete Columns

2012 ◽  
Vol 446-449 ◽  
pp. 3725-3729
Author(s):  
Wei Hua Ma ◽  
Hong Zhen Kang
Keyword(s):  
Experimental Study ◽  
Compressive Strength ◽  
Concrete Strength ◽  
Concrete Columns ◽  
Confined Concrete ◽  
Concrete Column ◽  
Compressive Behavior ◽  
Reinforcing Effect ◽  
Research Results ◽  
Compressive Tests

Compressive tests of 30 concrete column specimens with three concrete strength grades are carried out in this paper to study ultimate compressive strength of specimens. The specimens are divided into three groups, that is, unconfined, confined by CFRP with no initial compression and confined by CFRP with various initial compressions. The different initial compressions’ influence on ultimate stresses and strains are investigated. The decrease of CFRP reinforcing effect due to pre-compression are analyzed. The research results provide experimental datum for reinforced design of existing concrete columns.

FEM Analysis on Concrete Column Confined by Straps of BFRP Sheets

2013 ◽  
Vol 639-640 ◽  
pp. 1083-1086
Author(s):  
Xiao Kun Wang ◽  
Hua Xin Liu ◽  
Xue Zhi Wang ◽  
Cheng Zhai
Keyword(s):  
Compressive Strength ◽  
Axial Loading ◽  
Fem Analysis ◽  
High Strength ◽  
Confined Concrete ◽  
Concrete Column ◽  
Good Resistance ◽  
Axial Compressive Strength ◽  
Loading Tests ◽  
Strength And Ductility

More attention has been paid on the technology of BFRP in civil engineering due to it’s unique properties, such as high strength-to-weight radio, good resistance to corrosion and convenient to construction. In order to study the properties of BFRP sheets confined concrete column ,we did it through three groups of columns subjected to axial loading tests and FEM analyses, mainly considering the effect of spacing of straps of BFRP sheets confining concrete column.The results shows that the axial compressive strength and ductility of concrete column winded by BFRP straps have all increased and the process of destruction of concrete column wrapped by BFRP is longer than that of the unconfined concrete column.

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