• Magazine of the Korea Concrete Institute
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• v.8 no.2
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• pp.119-127
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• 1996

Objection of this study is to present the three-dimensional material nonlinear analysis of reinforced concrete. A concrete is idealized with three-dimensional 16-node solid element including triaxial nonlinear stress-strain behavior, cracking, crushing and strain softening: a steel with three-dimensional 3 node truss element including elastic-plastic behavior with strain hardening. The cracked shear retention factor is introduced to estimate the effective shear modulus con sidering aggregate interlock after c:racking and a modified newton method is used to obtain a nu merical solution. Numerical results in a gauss point is displayed graphically. Numerical examples of Krahl's reinforced concrete beam and Hedgreds shell are selected to compare with the experimental and numerical results.

• Journal of Korean Society of Steel Construction
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• v.24 no.1
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• pp.47-58
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• 2012

Dynamic behaviors of a corrugated steel plate tunnel lining system are examined under wind loads due to passing vehicles. Applied wind loads are simulated by applying the time functions as a vehicle moves through the tunnel. Wind loads are described by the pressure and suction as a vehicle arrives and leaves target positions in the tunnel. The tunnel lining is modeled using the simplified shell elements that retain the characteristics of the corrugated shapes. The displacements of the tunnel lining are evaluated under various conditions regarding wind velocity and the passing vehicles. The responses are found to increase as the vehicle velocity and wind velocity increase. A maximum displacement of 25mm occurs when two vehicles are crossing at the speed of 120km/h. A row of vehicles running consecutively minimally affects the dynamic responses with less than 2.5% of the dynamic responses enlarged and attributed to one running vehicle. It should be noted that the dynamic responses of the tunnel lining should be considered when there is no shotcrete applied.

• Computational Structural Engineering
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• v.8 no.2
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• pp.133-140
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• 1995

The buckling analysis of Glass Fiber Reinforced Plastic pipes was studied through a three dimentsional finite element method. In the finite element analysis, an improved degenerated shell element with incompatible modes and assumed shear strain fields are employed with 3 displacements and 2 rotations for each joints. Buckling analysis is carried out for various thicknesses and different fiber orientations. Finite element results show that the buckling load increases as the thickness does with the variation of coupling stiffness.

• Computational Structural Engineering
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• v.7 no.2
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• pp.139-146
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• 1994

In this study, the finite element analysis using joint elements, bolt elements, and shell elements is presented to investigate the behavior of bolted connections. The contact of plates and the high-strength, pretensioned bolts are simply idealized by joint elements and bolt elements, respectively. The initial stiffness is determined through the presented method and the non-linear analysis is archived by a constant-arc-length method based on Newton-Raphson method. The analysis results of a semi-rigid connection(web & flange angles) and a moment connection (shear & moment plates) demonstrate the exactness and applicability of the presented method. And the results indicates that the consideration of slip and 3-dimensional deformation is needed for an accurate prediction of bolted connections.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.13 no.3
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• pp.321-328
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• 2000

An improved formulation of thin-wailed curved beams with variable curvatures based on displacement field considering the second order terms of finite semitangential rotations is presented. From linearized virtual work principle by Vlasov's assumptions, the total potential energy is derived and all displacement parameters and the warping functions are defined at cendtroid axis. In developing the thin-walled curved beam element having eight degrees of freedom per a node, the cubic Hermitian polynomials are used as shape functions. In order to verify the accuracy and practical usefulness of this study, free vibrations and buckling analyses of parabolic and elliptic arche shapes with mono-symmetric sections are carried out and compared with the results analyzed by ABAQUS' shell element.

• Journal of Ocean Engineering and Technology
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• v.25 no.5
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• pp.52-57
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• 2011

Most ships and offshore structures are equipped with a variety of pipes, which inevitably contain curved portions. While it has been a usual practice to conduct bending stress analyses of these curved pipes using the straight-beam theory, this paper adopts two different types of finite elements, straight-beam elements and two-dimensional shell elements, for finite element analyses of a variety of curved pipes. It then compares the analysis results for two different types of elements to determine correction factors, which can be used to transform the bending displacements and bending stresses obtained by straight-beam elements to those obtainable by two-dimensional shell elements. The paper ends with a practical suggestion on how to efficiently use these correction factors to estimate the combined axial and normal stresses in a curved portion of a pipe.

• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.1
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• pp.129-138
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• 2004

In this study we determine a dynamic analysis of the existing two-span prestressed concrete box girder bridge subjected to moving vehicle loads using the experimental measurements. The moving loads applied in this paper are classified as general travelling, suddenly brake, continuous travelling, reversely travelling and reversely travelling impact loads for increasing velocities. For each travelling load, we search dynamic behaviors and characteristic in various measuring point of box girder section. In addition, the three-dimensional numerical results analyzed by the developed finite element program using flat shell element with six degrees of freedom per a node are compared with the measured experimental data. Dynamic behaviors caused impact loads by suddenly braking, reversely travelling, are bigger than by general travelling in box girder. Three-dimensional numerical results are better than one-dimensional results.

• Journal of the Korean Geotechnical Society
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• v.21 no.4
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• pp.123-134
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• 2005

A coupled three-dimensional pile group analysis method (YSGroup) was developed considering nonlinear pile head stiffness matrices and compared with other analytical methods (elastic displacement method, Group 6.0 and FBPier 3.0). In this method, a pile cap was modelled by four-node flat shell element, a pier was modelled using 3 dimensional beam element, and individual piles were modelled as beam-column elements. Through the comparative studies on a piled pie. subjected to lateral loads in linear soil, it was found that present method (YSGroup), elastic displacement method and Group 6.0 gave similar results of lateral pile head displacement, but FBPier 3.0 was estimated to show somewhat larger displacements than those from the three methods. Displacements of superstructure (pier), including nonlinear soil behavior, could be estimated by present method (YSGroup) and FBPier 3.0 because these two methods modelled the superstructure directly by finite element techniques. It was found that pile groups in pinned pile head condition had a tendency to cause excessive rotation of the pile cap.

• Journal of the Korean Society for Railway
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• v.15 no.6
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• pp.588-596
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• 2012

This paper presents a new semi-analytical annular Mindlin plate element with which out-of-plane natural vibration of thick disks can be analyzed simply, efficiently, and accurately through FEM by including effects of rotary inertia and transverse shear deformation. Using static deformation modes which are exact solutions of equilibrium equations of annular Mindlin plate, the element interpolation functions, stiffness and mass matrices corresponding to each number of nodal diameters are derived. The element is capable of representing out-of-plane rigid-body motions exactly and free from shear locking. Natural frequencies of uniform and multi-step disks with or without concentric ring support are analyzed by applying the presented element. Such results are compared with theoretical predictions of previous works or FEA results obtained by using two-dimensional shell element to investigate the convergence and accuracy of the presented element.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.6
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• pp.719-730
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• 2007

This study presents a thin-walled space frame element based on the classical Timoshenko beam theory. The element is derived according to the assumed strain field in order to resolve the shear-locking phenomenon. The shape function is developed in accordance with the strain field which is assumed to be constant at a 2-noded straight frame element. In this study, the geometrically nonlinear analysis applies the Corotational procedure in order to evaluate unbalanced loads. The bowing effect is also considered faithfully. Two numerical examples are given; monosymmetric curved and nonsymmetric straight cantilever. When these example structures behave lateral-torsional bucking, the critical loads are obtained by this study and ABAQUS shell elements. Also, the post-buckling behavior is examined. The results give good agreement between this study and ABAQUS shell.