• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.223-224
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• 2021

Recently, the demand for high fluidity concrete has been increased due to skyscrapers. However, it has its own limits. First of all, high fluidity concrete has large variation and through trial & error it costs lots of money and time. Neural network model has repetitive learning process which can solve the problem while training the data. Therefore, the purpose of this study is to predict optimum mix design of 40MPa, 60MPa high fluidity concrete by using neural network model and verifying compressive strength by applying real data. As a result, comparing collective data and predicted compressive strength data using MATLAB, 40MPa mix design error rate was 1.2%~1.6% and 60MPa mix design error rate was 2%~3%. Overall 40MPa mix design error rate was less than 60MPa mix design error rate.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.96-99
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• 2008

When the design modification is occurred, at present, design process based on 2-D spend more time and effort than that based on 3-D to modify related structural details. To improve and develop these processes, therefore, the design possibility of civil structures based on virtual model of 3-D must be investigated. We designed reinforced concrete pier of 3-D model, containing parameters. The parameters was defined as structural details like area of the section, reinforcement specification for design modification and structural analysis. In this paper, we researched about the processes modeling of reinforced concrete bridge pier based on parameters, the extracting data from the virtual model of 3-D, and the reflection of data to virtual model throughout structural analysis.

• Proceedings of the Korea Concrete Institute Conference
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• 1994.04a
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• pp.53-58
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• 1994

Beam-column joints of the skeleton structure can be classified as geometrical D-region, where the assumption of Bernoulli is not applicable. For the detailing of D-region in concrete structure, "Strut-and-Tie' Model is a very powerful tool, which has been widely used by practical engineers. This paper shows how the methodology of Strut-and-Tie Model can be applied for the various cases of beam-column joints. We can find this mechanical model does not give only an appropriate answer to the given problem but also a better insight to the structral behavior of beam-column joints.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.11a
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• pp.71-72
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• 2012

The purpose of this study is to evaluate the depth of carbonation considering the relative humidity in concrete using the FEM model. The difference of relative humidity in concrete has not been considered in calculating the carbonation depth in analytic model. That reason can make the over estimation in expectation of RC structure durability. The temperature and R.H. expectation model and the carbonation depth expectation model are development in past author's studies. The two models are coupled in this study. The fact that there is the difference between actual environment and acceleration test is revealed from FEM numerical analysis.

• Computers and Concrete
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• v.15 no.5
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• pp.709-733
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• 2015

This work deals with a damage model formulation taking into account the unilateral effect of the mechanical behaviour of brittle materials such as concrete. The material is assumed as an initial elastic isotropic medium presenting anisotropy, permanent strains and bimodularity induced by damage evolution. Two damage tensors governing the stiffness in tension or compression regimes are introduced. A new damage tensor in tension regimes is proposed in order to model the diffuse damage originated in prevails compression regimes. Accordingly with micromechanical theory, the constitutive model is validate when dealing with unilateral effect of brittle materials, Finally, the proposed model is applied in the analyses of reinforced concrete framed structures submitted to reversal loading. The numerical results have shown the good performance of the modelling and its potentialities to simulate practical problems in structural engineering.

• Structural Engineering and Mechanics
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• v.1 no.1
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• pp.17-30
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• 1993

A practical multi-spring model is proposed for a nonlinear analysis of reinforced concrete members, especially columns, taking into account the interaction of axial load and bi-directional bending moment. The parameters of the model are determined on the basis of material properties and section geometry. The axial force-moment interaction curve of reinforced concrete sections predicted by the model was shown to agree well with those obtained by the flexural analysis utilizing realistic stress-strain relations of materials. The reliability of the model was also examined with respect to the test of reinforced concrete columns subjected to varying axial load and bi-directional lateral load reversals. The analytical results agreed well with the experiment.

• International Journal of Concrete Structures and Materials
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• v.1 no.1
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• pp.19-28
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• 2007

A dynamic constitutive damage model for reinforced concrete (RC) structures and formulations of blast loading for contact or near-contact charges are considered and adapted from literatures. The model and the formulations are applied to the input parameters needed in commercial finite element method (FEM) codes which is validated by the laboratory blast tests of RC slabs from literature. The results indicate that the dynamic constitutive damage model based on the damage mechanics and the blast loading formulations work well. The framework on the dynamic constitutive damage model and the blast loading equations can therefore be used for the simulation of failure of bridge components in engineering applications.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.179-182
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• 2005

Recently, many design codes including ACI 318-02 recommend the use of a strut-tie model approach for design of structural concrete with D-region(s). However, there are several unclear problems and shortcomings in the codes' strut-tie model approach. A grid strut-tie model approach was proposed to resolve these problems. In this study, the ultimate strengths of 17 deep beams, the most familiar type of D-regions, were evaluated for the validity check of the grid strut-tie model approach. The analytical results obtained by the approach are compared with those by the strut-tie model approach presented by CEB-FIP, AASHTO LRFD, and ACI 318-02.

• Structural Engineering and Mechanics
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• v.6 no.4
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• pp.395-409
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• 1998

This paper concerns the development and implementation of an orthotropic, stress resultant elasto-plastic finite element model for the collapse load analysis of reinforced concrete plates. The model implements yield line plasticity theory for reinforced concrete. The behaviour of the yield functions are studied, and modifications introduced to ensure a robust finite element model of cases involving bending and twisting stress resultants ($M_x$, $M_y$, $M_{xy}$). Onset of plasticity is always governed by the general yield-line-model (YLM), but in some cases a switch to the stress resultant form of the von Mises function is used to ensure the proper evolution of plastic strains. Case studies are presented, involving isotropic and orthotropic plates, to assess the behaviour of the yield line approach. The YLM function is shown to perform extremely well, in predicting both the collapse loads and failure mechanisms.

• Proceedings of the KSR Conference
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• 1998.11a
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• pp.39-46
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• 1998

This paper is about design for diaphragm of prestressed concrete box bridge using strut-tie model. In this paper, equivalent loads for the diaphragm are computed by considering loading conditions on continuous prestressed concrete box bridge and analyses for both longitudinal section and transverse section of the diaphragm an done by considering the equivalent loading and the prestressing. Based on principal stress trajectory obtained from the analyses, strut-tie model for each sections are constructed. By analyzing the constructed strut-tie model for each sections, the amounts and the locations of reinforcement for the diaphragm are obtained. The application of strut-tie model in this paper shows that the design by soul-tie model for the diaphragm of prestressed concrete box bridges can be rationally performed.