• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.03a
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• pp.349-361
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• 2003

For performance-base design using nonlinear static analysis, it is required to predict the inelastic behavior of structural members accurately. In the present study, nonlinear numerical analysis was performed to develop the method describing the moment-curvature relationship of structural wall with boundary confinement. Through the numerical analysis, variations of behavioral characteristics and failure mechanism with the arrangement of vertical reiforcement and the length of boundary confinement were studied. Based on the findings, moment-curvature curves and curvature capacity for walls with a variety of re-bar arrangement was developed. By equalizing curvature capacity to demand, a design method which can determine the length of boundary confinement, was developed and for the effectiveness of boundary confinement and constructability, boundary confinement detail was proposed.

• Structural Engineering and Mechanics
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• v.59 no.1
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• pp.59-82
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• 2016

Simplifier assumptions which are used in numerical studies of progressive collapse phenomenon in structures indicate inconsistency between the numerical and experimental full-scale results. Neglecting the effects of infill panels and two-dimensional simulation are some of these assumptions. In this study, an existing seismically code-designed steel building is analyzed with alternate path method (AP) to assess its resistance against progressive collapse. In the AP method, the critical columns be removed immediately and stability of the remaining structure is investigated. Analytical macro-model based on the equivalent strut approach is used to simulate the effective infill panels. The 3-dimentional nonlinear dynamic analysis results show that modeling the slabs and infill panels can increase catenary actions and stability of the structure to resist progressive collapse even if more than one column removed. Finally, a formula is proposed to determine potential of collapse of the structure based on the quantity and quality of the produced plastic hinges in the connections.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.11
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• pp.1743-1750
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• 2001

This paper presents an analysis of nonlinear response of the seismically isolated structure against earthquake excitation to evaluate isolation performances of a rubber bearing. In the analysis of the vibration of building, the building is modeled by lumped mass system where the restoring force is considered as linear, bilinear and trilinear. Fundamental equations of motion are derived for the base isolated structure, and hysteretic and nonlinear-elastic characteristics are considered for a numerical calculation. The excitation levels are magnified fur the recorded strong earthquake motions in order to examine dynamic stability of the structure. Seismic responses (of the building are compared fur the each restoring force type. As a result, it is shown that the effect of the motion by the nonlinear response of the building is comparatively not so large from a seismic design standpoint. The responses of the isolated structures reduce sufficiently and controled the motion of the building well in a practical range. By increasing the acceleration of the earthquake, the yielding of the farce was occurred in the concrete and steel frame, which shows the necessity of the exact nonlinear dynamic analysis.

• Journal of the Korean Geotechnical Society
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• v.29 no.3
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• pp.29-40
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• 2013

Seismic response of single degree of freedom system supported by shallow foundation was analyzed by using nonlinear explicit finite difference element code. Numerical analysis results were verified with dynamic centrifuge test results of the same soil profile and structural dimensions with the numerical analysis model at a centrifugal acceleration of 20 g. Differences between the analysis and the test results induced by the boundary conditions of control points can be reduced by adding additional local damping to the natural born cyclic hysteretic damping of the soil strata. The analysis results show good agreement with the test results in terms of both time histories and response spectra. Thus, it can be concluded that the nonlinear explicit finite difference element code will be a useful technique for estimating seismic residual displacement, earthpressure etc. which are difficult to measure during laboratory tests and real earthquake.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.4
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• pp.159-168
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• 2005

This study carries out a finite difference nonlinear analysis of anisotropic advanced composite plate structures with various layer sequences. In the numerical analysis of various mechanical problems involving complex partial differential equations, the finite difference method (FDM) developed in this study has an advantage over the finite element method in its ability to avoid mesh generation and numerical integration. Many studies in FDM have been made on clamped or simple boundary conditions using merely an energy approach. These approaches cannot be satisfied, however, with pivotal points along the free boundary. Therefore, this study addresses the nonlinear problem of anisotropic plates by adopting a finite difference modeling elimination of pivotal difference points in the case of a free boundary condition. Complex nonlinear behaviors of composite plate structures for various parameters, especially for layer sequences, are analyzed using the proposed approach.

• Journal of applied mathematics & informatics
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• v.7 no.1
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• pp.215-222
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• 2000

A multigrid algorithm is developed for solving the one- dimensional initial boundary value problem. The numerical solutions of linear and nonlinear Burgers; equation for various initial conditions are studied. The stability conditions are derived by Von -Neumann analysis . Numerical results are presented.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.971-976
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• 2006

This paper presents a design technique of steel structures subjected to static and dynamic loadings using practical nonlinear inelastic analysis software. The beam-column approach using the stability functions and the plastic hinge concept enables the software to suitably predict second-order effects and inelastic behavior of beam-columns. For dynamic analysis. the incremental from of the equation of motion is solved by the use of a step-by-step numerical integration procedure in which the assumption of constant acceleration over a small time step is employed. The accuracy of the analysis program is validated using the results of ABAQUS program and experimental tests. A user-friendly graphic interface of the software is developed to facilitate the modeling process and result interpretation of the problem. A design example of large span bridge is presented to detail the direct design process using the practical advanced analysis software.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.03a
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• pp.422-429
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• 2003

A comparative study was performed for a suspension bridge to grasp the possible differences in seismic responses evaluated by several analytical methods. The items mainly investigated are the linear vs. nonlinear response the response spectrum method vs. the linear dynamic analysis method and the damping ratio and it's implementation into analysis procedures. According to the numerical example, it is found that the seismic responses are considerably affected by the damping-related parameters even though slight differences are shown depending on the response quantities md the exciting directions. On the other hand, it is also confirmed that the seismic responses are less affected by the analysis method-related parameters such as the response spectrum method vs. the linear dynamic analysis method, and the linear and nonlinear analysis method. The response spectrum method is expected to give conservative results for the examined bridge, provided that the design response spectrum in the Korean Highway Design Specification is modified according to the proper damping ratio.

• Journal of the korean Society of Automotive Engineers
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• v.13 no.3
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• pp.58-67
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• 1991

A theory of continuum damage mechanics based on the theory of materials of type N was developed and its nonlinear finite element approximation and numerical simulation was carried out. To solve the finite elastoplasticity problems, reasonable kinematics of large deformed solids was introduced and constitutive relations based on the theory of materials of type-N were derived. These highly nonlinear equations were reduced to the incremental weak formulation and approximated by the theory of nonlinear finite element method. Two types of problems, compression moulding problem and pure bending problem, were solved for aluminum 2024.

• Journal of the Society of Naval Architects of Korea
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• v.37 no.1
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• pp.67-81
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• 2000

An accurate and efficient numerical method for two-dimensional nonlinear radiation problem has been developed. The wave motion due to a moving body is described by the assumption of ideal fluid flow, and the governing Laplace equation can be effectively solved by the higher-order boundary element method with the help of the GMRES (Generalized Minimal RESidual) algorithm. The intersection or corner problem is resolved by utilizing the so-called discontinuous elements. The implicit trapezoidal rule is used in updating solutions at new time steps by considering stability and accuracy. Traveling waves caused by the oscillating body are absorbed downstream by the damping zone technique. It is demonstrated that the present method for time marching and radiation condition works efficiently for nonlinear radiation problem. To avoid the numerical instability enhanced by the local gathering of grid points, the regriding technique is employed so that all the grids on the free surface may be distributed with an equal distance. This makes it possible to reduce time interval and improve numerical stability. Special attention is paid to the local flow around the body during time integration. The nonlinear radiation force is calculated by the "acceleration potential technique". Present results show good agreement with other numerical computations and experiments.