• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.463-468
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• 2003

A finite element formulation to predict the flexural behavior of composite girder is presented in which the early-age properties of concrete are specified including maturing of elastic modulus, creep and shrinkage. The time dependent constitutive relation accounting for the early-age concrete properties is derived in an incremental format by expanding the total form of stress-strain relation by the first order Taylor series with respect to the reference time. The total potential energy of the flexural composite member is minimized to derive the time dependent finite element equilibrium equation. Numerical applications are made for the 3-span double composite steel box girders which is a composite bridge girder filled with concrete at the bottom of the steel box in the negative moment region. The numerical analysis with considering the variation of concrete elastic modulus are performed to investigate the effect of it on the early-age behavior of composite structures. The one dimensional finite element analysis results are compared with the analytical method based on the sectional analysis. Close agreement is observed among the two methods.

• Journal of the Korean Wood Science and Technology
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• v.23 no.3
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• pp.40-47
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• 1995

This study was carried out to develop a finite element analysis model that considers the semi-rigid characteristics of a wood-dowel joint, which is different from conventional joints that are used in the field of engineering. Wood-dowel joints are classified as semi-rigid joints that possess the following characteristics: (1) they are less stiffer than rigid joints and (2) their stiffness is determined by the dowel's diameter, depth of dowel embedment in the face member and quantity of pin dowels. In this study a finite element model that considers the changes in stiffness according to the above mentioned factors was developed and its suitability was verified by experiments using a wood-dowel joint test specimen made up of particleboards. After comparing the experimental results and the analysis results of the wood-dowel joint which was applied with the proposed finite element model, less than 10% of error was found which is considered to be negligibly small. Hence this shows that this proposed finite element model can be used to predict deformation of wood-dowel joints.

• Journal of the Korean Society for Advanced Composite Structures
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• v.1 no.1
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• pp.16-26
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• 2010

In this paper, we present the result of investigations pertaining to the development of the floating type photovoltaic energy generation system. Pultruded FRP has superior mechanical and physical properties compared with those of conventional structural materials. Since the FRP has an excellent corrosion-resistance and high specific strength and stiffness, the FRP material may be highly appreciated for the development of the floating type photovoltaic energy generation system. In the paper, we discussed the development concepts of the floating type photovoltaic energy generation system, briefly. The mechanical properties of the FRP structural member used in the development are investigated through the tensile and compression tests. Test results are used in the finite element analysis and the design of the system. In addition, bolted connections of the members are briefly discussed and the strengths of FRP bolted connections are estimated based on the results of experiments. The experimental results are compared with the finite element analysis results and discussed briefly. The floating type photovoltaic energy generation system is designed, fabricated, and installed successfully in site.

• Journal of Korean Association for Spatial Structures
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• v.1 no.2 s.2
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• pp.59-66
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• 2001

This paper describes three modules for development of the Space Frame Integrated Design System(SFIDS). The Control Module is implemented to control the developed system. The Model Generation Module based on PATRAN user interface enables users to generate a complicated finite element model for space frame structures. The Optimum Design Module base on a branch of combinatorial optimization techniques which can realize the optimization of a structure having a large number of members designs optimum members of a space frame after evaluating analysis results. The Control Module and the Model Generation Module Is implemented by PATRAN Command Language(PCL) while C++ language is used in the Optimum Design Module. The core of the system is PATRAN database, in which the Model Generation Module creates information of a finite element model. Then, PATRAN creates Input files needed for the analysis program from the information of the finite element model in the database, and in turn, imports output results of analysis program to the database. Finally, the Optimum Design Module processes member grouping of a space frame based on the output results, and performs optimal member selection of a space frame. This process is repeated until the desired optimum structural members are obtained.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1998.04a
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• pp.210-215
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• 1998

To design a space frame structure by the conventional method is not easy in practical sense since it is generally a three-dimensional complicated form, and stability and nonlinear problems are not easily checked in the design process. This paper describes two modules, the Model Generator which is based on PATRAN user interface that enables users to generate a complicated finite element model; the Optimum Design Module which analyzes output results of analysis program, and designs members of a space frame. The Model Generator is based on PCL while C++ language is used in the Optimum Design Module. Structural analysis is performed by using ABAQUS. All of these modules constitute Space Frame Integrated Design System. The Core of the system is PATRAN database, in which the Model Generator creates information of a finite element model. Then, PATRAN creates input files needed for the analysis program from the information of the finite element model in the database, and in turn, imports output results of analysis program to the database. Finally, the Optimum Design Module processes member grouping of a space frame based on the output results, and performs optimal member selection of a space frame. This process is repeated until the desired optimum structural members are obtained.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.5
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• pp.1069-1078
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• 1990

It is shown that the performance of finite element based on energy orthogonal functions may be superior to conventional formulation for plane stress problem. Using this finite element, it is then attempted to show the distribution of stress concentration effect for subsurface under loading point. It turned out that the stress concentration effect for subsurface is not dependent on the width of the member but the loading area. And then it is shown that the solution attained by taking the stress function as a Fourier series is not satisfactory in y<0.1B.

• Magazine of the Korean Society of Agricultural Engineers
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• v.41 no.4
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• pp.104-112
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• 1999

Tensile behavior in concrete has been neglected until recently. However, the effect of tensile stresses in concrete must be considered where the member primarily carries tensile forces or when ultimate strength is affected by the cracking history. In this paper, a series of experiments were performed with a reinforced rectangular beams of 15 specimens in order to investigate the effect of tension stiffening into the nonlinear analysis and cracking behavior. The experimental results were analyzed in terms of load-deflection curves and strain fracture energy with respect to the main experimental variables such as types of specimen, strength of concrete and steel ration. The results from experiments and finite element analysis were compared in terms of load-deflection relationship and cracking pattern. The results are as follows ; The tension stffening effects of reinforced concrete beams were observedc up to yielding of members after cracking showing strain energy difference of 35 % at the beam of 0.57% steel ratio compared with that of beam ignoring the tension stiffening effect. The tension stiffening of concrete strength 400kgf/$\textrm{cm}^2$ and 600kgf/$\textrm{cm}^2$ increased by 8% and 13%, respectively, compared with that of concrete strength 200kgf/$\textrm{cm}^2$. The tension stiffening effects were greater at a ductile member rather than a brittle one. The load-deflection results of finite element analysis showed very similar results from experiment. The crack growth and pattern might be predicted from the nonlinear finite element analysis considering concrete stiffening.

• Journal of the Korean Society of Safety
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• v.27 no.3
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• pp.104-110
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• 2012

It is a common practice to design basement walls acting as a one-way slab or plate with idealized boundary conditions, resulting in potentially inefficient design. The walls are often supported by buttress columns and side walls in the vertical direction, thereby acting as a two-way slab. In this study, structural behavior of single-story, three-span basement wall subjected to lateral soil pressure was investigated. Three dimensional finite element analyses were conducted to determine the force distribution on the wall. Based on the numerical studies, a regression analysis was carried out to determine the design values of moments in vertical and horizontal directions as well as shear forces on the wall and design charts are developed. The proposed design method with accompanying design charts would enable practicing engineers to estimate member forces on the wall for preliminary design purpose without resorting to finite element analysis. Numerical examples demonstrated the applicability of the proposed method.

• Structural Engineering and Mechanics
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• v.8 no.3
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• pp.257-272
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• 1999

In this paper a simple finite element is proposed for analyzing out of plane vibration of thin walled curved beams, with both open and closed sections, considering shear flexibility. The present element is obtained from a variational formulation governing the dynamics of a three-dimensional elastic body in which the stress tensor as well as the displacements are variationally independent. The element has two nodes with four degrees of freedom in each. Numerical examples for the first six frequencies are performed in order to assess the accuracy of the finite element formulation and to show the influence of the shear flexibility on the dynamics of the member.

• Structural Engineering and Mechanics
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• v.9 no.2
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• pp.111-126
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• 2000

Truss type structures are attractive to a variety of engineering applications on earth as well as in space due to their high stiffness to mass ratios and ease of construction and fabrication. During the service life, an individual member of a truss structure may lose load carrying capacity due to many reasons, which may lead to collapse of the structure. An analytical and computational procedure has been developed to study the response of truss structures subject to member failure under static and dynamic loadings. Emphasis is given to the dynamic effects of member failure and the propagation of local damage to other parts of the structure. The methodology developed is based on nonlinear finite element analysis technique and considers elasto-plastic material nonlinearity, postbuckling of members, and large deformation geometric nonlinearity. The pseudo force approach is used to represent the member failure. Results obtained for a planar nine-bay indeterminate truss undergoing sequential member failure show that failure of one member can initiate failure of several members in the structure.