• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.37-42
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• 2001

This paper presents the improved elastic modulus equation more appropriate to predict the modulus of elasticity of structural elements designed and made by high-strength concrete. To propose the elastic modulus equation, more than 300 laboratory specimen tests having the range of 5n to 800kgf/$cm^{2}$ in concrete compressive strength were conducted and analyzed statistically. The equation derived in terms of empirical constant, the elastic moduli of coarse aggregate and mix proportions. Comparison of the proposed elastic modulus equation with the previously suggested equations in the ACI363R, and New-RC were also presented to demonstrate the applicability to practice.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.933-943
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• 2009

Axial loads and shaft resistances can be calculated by load transfer analysis using strain data with load level. In load transfer analysis, the elastic modulus of concrete is a one of the most important parameters to consider. The elastic modulus, $E_{50}$, suggested by ACI (American Concrete Institute), has been commonly used. However, elastic modulus of concrete shows nonlinear stress-strain characteristic, so nonlinearity should be considered in load transfer analysis. In this paper, a load transfer analysis was performed by using data obtained from bi-directional pile load tests for four cases of drilled shafts. For consideration of nonlinearity, elastic modulus was calculated by both the Fellenius method and the nonlinear method, assuming the stress-strain relation of concrete to be a quadratic function, and then, the calculated elastic modulus was applied to the estimation of shaft resistance. The calculated shaft resistances were compared with the result obtained using the constant elastic modulus of ACI code. It was found that the f-w curves are similar to each method, and elastic modulus and shaft resistances decreased as strain increased. Moreover, shaft resistances estimated from elastic modulus considering nonlinearity were 5~15% different than those obtained using the constant elastic modulus.

• International Journal of Safety
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• v.11 no.1
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• pp.19-21
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• 2012

In this thesis, fracture test was performed in order to investigate the fracture strength of SFRC(steel fiber reinforced concrete) structures. The relationship between the compressive force and strain value of SFRC specimens were observed under the compressive strength test. From the fracture test results, the relationship between percentage of fiber by volume, compressive strength, elastic modulus, and tensile strength of SFRC beams were studied, and the measured elastic modulus of SFRC were compared with the calculated elastic modulus by ACI committee 544.

• Journal of Information Processing Systems
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• v.18 no.4
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• pp.457-469
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• 2022

Hydraulic concrete buildings in the northwest of China are often subject to the combined effects of low-temperature frost damage, during drying and wetting cycles, and salt erosion, so the study of concrete deterioration prediction is of major importance. The prediction model of the relative dynamic elastic modulus (RDEM) of four different kinds of modified concrete under the special environment in the northwest of China was established using Grey residual Markov theory. Based on the available test data, modified values of the dynamic elastic modulus were obtained based on the Grey GM(1,1) model and the residual GM(1,1) model, combined with the Markov sign correction, and the dynamic elastic modulus of concrete was predicted. The computational analysis showed that the maximum relative error of the corrected dynamic elastic modulus was significantly reduced, from 1.599% to 0.270% for the BS2 group. The analysis error showed that the model was more adjusted to the concrete mixed with fly ash and mineral powder, and its calculation error was significantly lower than that of the rest of the groups. The analysis of the data for each group proved that the model could predict the loss of dynamic elastic modulus of the deterioration of the concrete effectively, as well as the number of cycles when the concrete reached the damaged state.

• Computers and Concrete
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• v.20 no.1
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• pp.49-56
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• 2017

A clear correlation exists between the compressive strength and elastic modulus of concrete. Unfortunately, determining the static elastic modulus requires destructive methods and determining the dynamic elastic modulus is greatly complicated by the shape and size of the specimens. This paper reports on a novel approach to the prediction of compressive strength in concrete cylinders using numerical calculations in conjunction with the impact-echo method. This non-destructive technique involves obtaining the speeds of P-waves and S-waves using correction factors through numerical calculation based on frequencies measured using the impact-echo method. This approach makes it possible to calculate the dynamic elastic modulus with relative ease, thereby enabling the prediction of compressive strength. Experiment results demonstrate the speed, convenience, and efficacy of the proposed method.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.105-108
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• 2005

This study investigated fundamental properties of the recycled aggregate which was produced through recent hi-techniques of recycling. In addition, the mechanical properties of the concrete that used the recycled aggregate were compared to the concrete used the natural aggregate. From the results of the mechanical property tests, as the recycled aggregate replacement ratio increased, the compressive strength and elastic modulus decreased. When the recycled aggregate completely replaced the natural aggregate, the compressive strength and elastic modulus was about 15$\%$ and 35$\%$ lower than the natural aggregate concrete, respectively. Based on the test results, equations for prediction of compressive strength and elastic modulus were suggested in the consideration of the amount of the replaced recycled aggregate. Based on the test results and study, the equation predicting the required development length of the recycled aggregate concrete is proposed.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10a
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• pp.245-250
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• 1998

The Elastic modulus depends on the elastic property of composition materials, the gravity of aggregate, the bond strength of binder, the usage and quantity of admixture, curing and measuring method, etc. Accordingly, the aim of this study, by manufacturing concrete of practical high strength range(600~ 1000kg/$\textrm{cm}^2$) with the specific cement and mineral admixtures, is to compare elastic modulus with the existing equations and also to estimate elastic property of use materials. As a result, it could be confirmed that the existing equations which were proposed by the ACI 363, CEB-FIP Code, and New-RC have a tendency to the overestimation in general. However, it could be confirmed that the KCI-96 and Norwegian NS 3473 equations are closed to measuring results, and that the elastic modulus property have a different tendency due to types of cements.

• Steel and Composite Structures
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• v.44 no.3
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• pp.309-324
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• 2022

The post-fire elastic stiffness and performance of concrete-filled steel tube (CFST) columns containing recycled aggregate concrete (RAC) has rarely been addressed, particularly in terms of material properties. This study was conducted with the aim of assessing the modulus of elasticity of recycled aggregate concrete-filled steel tube (RACFST) stub columns following thermal loading. The test data were employed to model and assess the elastic modulus of circular RACFST stub columns subjected to axial loading after exposure to elevated temperatures. The length/diameter ratio of the specimens was less than three to prevent the sensitivity of overall buckling for the stub columns. The gene expression programming (GEP) method was employed for the model development. The GEP model was derived based on a comprehensive experimental database of heated and non-heated RACFST stub columns that have been properly gathered from the open literature. In this study, by using specifications of 149 specimens, the variables were the steel section ratio, applied temperature, yielding strength of steel, compressive strength of plain concrete, and elastic modulus of steel tube and concrete core (RAC). Moreover, parametric and sensitivity analyses were also performed to determine the contribution of different effective parameters to the post-fire elastic modulus. Additionally, comparisons and verification of the effectiveness of the proposed model were made between the values obtained from the GEP model and the formulas proposed by different researchers. Through the analyses and comparisons of the developed model against formulas available in the literature, the acceptable accuracy of the model for predicting the post-fire modulus of elasticity of circular RACFST stub columns was seen.

• Computers and Concrete
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• v.9 no.5
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• pp.389-402
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• 2012

In this study, the modulus of elasticity of low, normal and high strength steel fiber reinforced concrete has been predicted by developing a fuzzy logic model. The fuzzy models were formed as simple rules using only linguistic variables. A fuzzy logic algorithm was devised for estimating the elastic modulus of SFRC from compressive strength. Fibers used in all of the mixes were made of steel, and they were in different volume fractions and aspect ratios. Fiber volume fractions of the concrete mixtures have changed between 0.25%-6%. The results of the proposed approach in this study were compared with the results of equations in standards and codes for elastic modulus of SFRC. Error estimation was also carried out for each approach. In the study, the lowest error deviation was obtained in proposed fuzzy logic approach. The fuzzy logic approach was rather useful to quickly and easily predict the elastic modulus of SFRC.

• Computers and Concrete
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• v.7 no.6
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• pp.497-510
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• 2010

For better estimation of elastic property of concrete composites, the effect of Interfacial Transition Zone (ITZ) has been found to be significant. Numerical concrete composites models have been introduced using Finite Element Method (FEM), where ITZ is modeled as a thin shell surrounding aggregate. Therefore, difficulties arise from the mesh generation. In this study, a numerical concrete composites model in 3D based on FEM and random unit cell method is proposed to calculate elastic modulus of concrete composites with ITZ. The validity of the model has been verified by comparing the calculated elastic modulus with those obtained from other analytical and numerical models.