• Journal of Korean Tunnelling and Underground Space Association
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• v.14 no.3
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• pp.159-181
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• 2012

The segment lining which consists of segments and joints are main component of shield tunnel. There are a number of methods that are being used in design which compute the sectional forces of a ring of segment lining. The traditional design methods which do not consider the effect of joints have been commonly used for design procedure without a specific verification of structural analysis. This paper presents the result of a comparative study for analytical and numerical models of the shield tunnel segment lining. For the traditional methods, the elastic equation method and the Duddeck & Erdmann method were considered. The ring-beam and the continuum analysis model were also considered as the numerical model.

• Journal of Navigation and Port Research
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• v.27 no.5
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• pp.519-526
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• 2003

For preliminary structural analysis of superstructures on very large floating structures(VLFS), superstructures are analyzed considering elastic deformations of barge type lower-structures subjected to wave loads. In this case, to consider the effect of wave loads on the superstructure, initial displacements at the support points of superstructures are evaluated as input data for the analysis. However, the evaluation and application of displacement loads are tedious and very time-consuming processes. Therefore, this paper proposes a simplified static analysis method to analyze the structural behaviors of superstructures on very large floating structures subjected to wave loads. In this study, the member forces due to the variation of beam span and the amplitude and period of wave load are analyzed by using an example 4 span -3 story structure and the amplification factors for beam moments are represented by the specific regression equation.

• Journal of the Korea Concrete Institute
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• v.20 no.3
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• pp.345-356
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• 2008

In the previous study, direct inelastic strut-and-tie model (DISTM) was developed to perform inelastic design of reinforced concrete members by using linear analysis for their secant stiffness. In the present study, for convenience in design practice, the DISTM was further simplified so that inelastic design of reinforced concrete members can be performed by a run of linear analysis, without using iterative calculations. In the simplified direct inelastic strut-and-tie model (S-DISTM), a reinforced concrete member is idealized with compression strut of concrete and tension tie of reinforcing bars. For the strut and tie elements, elastic stiffness or secant stiffness is used according to the design strategy intended by engineer. To define the failure criteria of the strut and tie elements, concrete crushing and reinforcing bar fracture were considered. The proposed method was applied to inelastic design of various reinforced concrete members including deep beam, coupling beam, and shear wall. The design results were compared with the properties and the deformation capacities of the test specimens.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.5
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• pp.39-52
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• 1993

For the lateral-torsional buckling analysis of the thin-walled space frame and circular arch with the unsymmetric cross section, the tangent stiffness matrices are derived by introducing Vlasov's assumption for the thin-walled beam and using the principle of virtual displacement. In the cases of the unrestrained torsion and the restrained torsion, the elastic and geometric stiffness matrices corresponding to semitangential rotation and semitangential moment are evaluated by using the Hermitian polynomials as the shape function. In order to illustrate the accuracy and convergence characteristics of the derived formulations, numerical examples for the lateral-torsional buckling analysis of the hinged circular arch under pure bending and uniform compression are presented and compared with the analytic solutions of references.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.5
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• pp.337-343
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• 2017

As a shop practice, a strength estimation method for die cast parts is suggested, in which various defects such as pores can be allowed. The equivalent porosity is evaluated by combining the stiffness data from a simple elastic test at the part level during the shop practice and the theoretical stiffness data, which are defect free. A porosity equation is derived from Eshelby's inclusion theory. Then, using the Mori-Tanaka method, the porosity value is used to draw a stress-strain curve for the porous material. In this paper, the Hollomon equation is used to capture the strain hardening effect. This stress-strain curve can be used to estimate the strength of a die cast part with porous defects. An elastoplastic theoretical solution is derived for the three-point bending of a die cast beam by using the plastic hinge method as a reference solution for a part with porous defects.

• Structural Engineering and Mechanics
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• v.65 no.3
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• pp.291-302
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• 2018

Rigid body spring method (RBSM) is an effective tool to simulate the cracking process of structures, and has been successfully applied to investigate the behavior of reinforced concrete (RC) members. However, the theoretical researches and engineering applications of this method mainly focus on two-dimensional problems as yet, which greatly limits its applications in actual engineering projects. In this study, a three-dimensional (3-D) RBSM for RC structures is proposed. In the proposed model, concrete, reinforcing steels, and their interfaces are represented as discrete entities. Concrete is partitioned into a collection of rigid blocks and a uniform distribution of normal and tangential springs is defined along their boundaries to reflect its material properties. Reinforcement is modeled as a series of bar elements which can be freely positioned in the structural domain and irrespective of the mesh geometry of concrete. The bond-slip characteristics between reinforcing steel and concrete are also considered by introducing special linkage elements. The applicability and effectiveness of the proposed method is firstly confirmed by an elastic T-shape beam, and then it is applied to analyze the failure processes of a Z-type component under direct shear loading and a RC beam under two-point loading.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.5
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• pp.521-526
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• 2014

In this study, closed-cell aluminum foam with an initial crack was investigated to produce an axial load-time graph. Using the 10-kN Landmarks of MTS Corporation, a 15-mm/min velocity of mode I shape was applied to the aluminum foam specimen using the displacement control method. ABAQUS 6.10 simulation was used to model and analyze the identical model in three dimensions under conditions identical to those of the experiment. The energy release rate was calculated on the basis of an axial load-displacement graph obtained from the experiment and a transient image of the crack length, and then an FE model was analyzed on the basis of this fracture energy condition. The relation between load and displacement was discussed; it was found that the aluminum foam deformed somewhat less than the adhesive layer owing to the difference in elastic modulus.

• Journal of Korean Society of Steel Construction
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• v.12 no.4 s.47
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• pp.387-395
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• 2000

The purpose of this research is to evaluate the capacity of strength and plastic deformation of those members, and provide experimental data on the seismic behavior of these members as a basis for developing guidelines for designing seismically resistant concrete-filled steel tubular columns. Eighteen cantilever-type specimens were tested under constant axial load and cyclically lateral load as models of bottom columns in high-rise building. The parameters studied in the test program included, are width-thickness ratio of steel tube, slenderness ratio (Lo/D) and axial force ratio. From the test results, the effects of parameters on the strength, the deformation capacity, energy absorption capacity are discussed. The specimen flexural capacity under combined axial and lateral loading was found to be almost accurately predicted by criteria AIJ and AISC-LRFD providing conservative results. Therefore KSSC for encased composite column can be applied to the concrete filled column if composite section and elastic modulus are modified according to AIJ and AISC-LRFD. Finally, the proposed flexural capacity considering confinement effects is a food agreement on the tests results.

• Journal of the Korea institute for structural maintenance and inspection
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• v.6 no.3
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• pp.193-199
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• 2002

Structral crack of RC structure generally occurs when the tension stress by applied load is larger than tension resistance of concrete, and it means deterioration of structure and the decrease of load resistance. Because structural crack of structure can occur critical damage to structure occasionally, the research on crack detection algorithm of RC structure is needed for assurance of structural safety and effective maintenance of structure. In this paper, we executed the laboratory test on measuring strain of RC beam's tension and compression zone, using strain gauge which is widely used on strain measurement of civil structure. By using measured strain, we analyzed strain change, elastic modulus change, and neutral axis change to detect crack of RC beam. As a result, we proposed the simple and effective crack detection algorithm using trends of neutral axis position change.

• Journal of the Society of Naval Architects of Korea
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• v.33 no.4
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• pp.142-149
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• 1996

Pyramid type three roll bending machines are widely used in roll-bending process to produce singly curved plate. In forming singly curved plate, controlling the vertical displacement of the center roller is most important to acquire the shape required and automation system of the process. In this paper roller bending process is modeled as an elastic-plastic phenomenon and analyzed using beam theory and finite element method. In finite element analysis the workpiece is modeled by using beam elements and plane strain elements respectively. Through the analyses vertical center roller displacement is obtained to get constant curvature distribution along arc length. The relationship between center roller displacement and curvature in steady state as well as residual stress and strain along plate thickness direction are calculated through finite element analysis.