• Journal of the Computational Structural Engineering Institute of Korea
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• v.15 no.2
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• pp.329-339
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• 2002

This research presents a systematic design procedure for supplemental viscoelastic dampers required to satisfy the given performance objectives using capacity spectrum method. To obtain required damper size, the amount of supplemental damping was computed from effective damping minus equivalent damping and inherent damping of structure. In the case of viscoelastic damper, iterative procedure is required because of the inherent stiffness of the damper. To verify the design method proposed in this study, parametric studies were performed for single degree of freedom systems with design variables. The method was also applied to a 10-story steel framed structure and the earthquake responses were obtained. According to time history analysis result the controlled displacements turned out to be close to the target displacement regardless of the design parameters.

• Journal of the Korean Geotechnical Society
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• v.38 no.12
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• pp.91-101
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• 2022

The 1995 Kobe earthquake caused a massive damage to the Port of Kobe. Therefore, it was pointed out that it was impossible to design port structures for Level II (Mw 6.5) earthquakes with quasi-static analysis and Allowable Stress Design methods. In Japan and the United States, where earthquakes are frequent, the most advanced design standards for port facilities are introduced and applied, and the existing seismic design standards have been converted to performance-based design. Since 1999, the Korean Port Seismic Design Act has established a definition of necessary facilities and seismic grades through research on facilities that require seismic design and their seismic grades. It has also established a performance-based seismic design method based on experimental verification. In the performance-based seismic design method of the breakwater proposed in this study, the acceleration time history on the surface of the original ground was subjected to a fast Fourier transform, followed by a filter processing that corrected the frequency characteristics corresponding to the maximum allowable displacement with respect to performance level of the breakwater and the filtered spectrum. The horizontal seismic coefficient for the equivalent static analysis considering the displacement was calculated by inversely transforming (i.e., subjected to an inverse fast Fourier transform) into the acceleration time history and obtaining the maximum acceleration value. In addition, experiments and numerical analysis were performed to verify the performance-based seismic design method of breakwaters suitable for domestic earthquake levels.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.4
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• pp.642-651
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• 1988

The present paper develops finite element procedures to calculate displacements, strains and stresses in initially stressed elastic solids subjected to static or time-dependent loading conditions. As a point of departure, we employ Hamilton's principle to obtain nonlinear equations of motion characterizing the displacement in a solid. The equations of motion reduce to linear equations of motion if incremental stresses are assumed to be infinitesimal. In the case of linear problem, finite element solutions are obtained by Newmark's direct integration method and by modal analysis. An analytic solution is referred to compare with the linear finite element solution. In the case of nonlinear problem, finite element solutions are obtained by Newton-Raphson iteration method and compared with the linear solution. Finally, the effect of the order of Gauss-Legendre numerical integration on the nonlinear finite element solution, has been investigated.

• Journal of the Korean Geotechnical Society
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• v.27 no.12
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• pp.85-96
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• 2011

A breakwater is a important structure for both calmness of harbor and protection of the port facilities from waves generated from typhoons or wind. This study adopted the rubble mound breakwater, which is one of the most popular type of breakwaters in Korea. Rubble mound breakwater had been designed by considering only static condition previously. Recently, a dynamic wave-load due to waves has been also considered in designing breakwater. In design, the wave-load is assumed as an uniform load which only acts in the front slope of the breakwater. However, the assumption is not applicable in reality. In this study, therefore, a real-time wave-load acting on the breakwater instead of the uniform load is considered, and it is assumed to be acting on the seabed too. Based on the numerical analysis, it is found that there is a significant difference in the maximum settlement compared with the result predicted by the existing design method.

• Journal of the Earthquake Engineering Society of Korea
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• v.3 no.3
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• pp.21-32
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• 1999

A ground motion resulting from the destructive earthquakes can subject reinforced concrete members to very large forces. The reinforced concrete shear walls are designed as earthquake-resistant members of building structure in order to prevent severe damage due to the ground motions. The current research activities on seismic behavior of reinforced concrete member under ground motions have been limited to the shaking table test or equivalent static cyclic test and the obtained results have been summarized and proposed for the seismic design retrofit of structural columns or shear walls. The present study predicted the seismic response and failure behavior of reinforced concrete shear wall subjected to base acceleration using the finite element method. A decrease in strength and stiffness, yielding of reinforcing bar, and repetition of crack closing and opening due to seismic load with cyclic nature are accompanied by the crack which is necessarily expected to take place in concrete member. In this study the nonlinear material models for concrete and reinforcing bar based on biaxial stress field and algorithm of dynamic analysis were combined to construct the analytical program using the finite element method. The analytical seismic response and failure behaviors of reinforced concrete shear wall subjected to several base accelerations were compared with reliable experimental result.

• Journal of the Earthquake Engineering Society of Korea
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• v.7 no.2
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• pp.75-84
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• 2003

Most structures are expected to deform beyond the limit of linearly elastic behavior when subjected to strong ground motion. Seismic evaluation of structure requires an estimation of the structural performance in terms of displacement demand imposed by earthquakes on the structure. The nonlinear response history analysis(NRHA) among various nonlinear analysis methods is the most accurate to compute seismic performance of structures, but it is time-consuming and necessitate more efforts. The nonlinear approximate methods, which is more practical and reliable tools for predicting seismic behavior of structures, are extensively studied. Among them, the capacity spectrum method(CSM) is conceptually simple, but the iterative procedure is time-consuming and may sometimes lead to no solution or multiple solutions. This paper considers a nonlinear direct spectrum method(NDSM) to evaluate seismic performance of mixed building structures without iterative computations, given dynamic property T from stiffness skeleton curve and nonlinear pseudo acceleration $A_{y}$/g and/or ductility ratio $\mu$ from response spectrum. The nonlinear response history analysis has been performed and analyzed with various earthquakes for estimation of reliability and practicality of NDSM with mixed building structures.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.4
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• pp.97-107
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• 2006

This study is structural analysis and continuous, discrete optimum design of braced steel frame structures under earthquake loads considering soil condition. The program which is able to perform simultaneously structural analysis and continuous, discrete optimum design, it is applied steel frame structures using unbraced, Z-braced, and X-braced types and analyze the program about static loads and seismic loads. The purpose of this study is to present proper braced type for seismic effects by comparing and analyzing results of analytic method about various cases using specially Newmark-Hall design spectrum, ATC design spectrum and ATC equivalent static analysis and finding minimum weight and design variables which satisfy the ultimate strength requirements of AISC-ASD specifications, the serviceability requirements and allowable story drift requirements of ATC-3-06 and various constraints.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.1
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• pp.53-60
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• 2016

This study discusses the thermal insulation capacity of variant of NO96 LNG (liquefied natural gas) cargo containment insulation system. Changing the insulation materials and the insulation layers of conventional GTT NO96 containment system, The thermal resistance and BOR(boil off rate) caused by the heat transfer between cryogenic and environmental temperature is discussed. Therefore, thermal analysis of LNG CCS(cargo containment system) is carried out to determine the insulation capabilities. Also, BOR is evaluated in terms of the total amount of heat invaded into CCS(cargo containment system). Variant of NO96 CCS such as NO96, NO96GW and NO96L3 membrane type during laden voyage is selected for the comparative study. Finite element model for heat transfer analysis is conducted by employing the equivalent thermal resistance model to simplify the complex insulation layers. Finally the results for each variant model are relatively compared and discussed to minimize the BOR.

• Journal of the Korean Wood Science and Technology
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• v.44 no.1
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• pp.48-56
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• 2016

In this study, to develop the lattice materials with a low environmental load for restoring the destroyed forest, 7 types of wood-concrete hybrid laminated materials were manufactured with domestic four softwoods, three hardwoods and concrete, and the effects of density of wood species on static bending strength performances were investigated. Bending MOEs of wood-concrete hybrid laminated materials increased with increasing density of wood species on the whole, and the values were higher than that of concrete by hybrid-laminating woods on the concrete. It was found that the measure values of bending MOEs were slightly lower than the calculated values calculated using equivalent cross-section method from MOE of each laminae of hybrid laminated materials and the difference between them was less than 10%. Bending proportional limit stresses of hybrid laminated materials showed 1.2-1.6 times higher than that of concrete by hybrid-laminating. Bending strength (MOR) of hybrid laminated materials increased with the density of wood species. By hybrid-laminating, the MOR of concrete was considerably increased. Therefore, it is considered that wood-concrete hybrid laminated materials can be applied as a materials with a low environmental load and durability for ecological restoration.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.6
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• pp.166-172
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• 2016

This paper deals with the seismic qualification of the reflective metal insulation for thermal shielding that is installed on the outer surfaces of the main equipment of the primary coolant system of a nuclear power plant. A small-scale model of the reactor pressure vessel, which has equivalent dynamic characteristics, was designed to be tested in domestic seismic testing facilities in the future. In this study, seismic analysis of the small-scale model installed with metal insulation was performed using equivalent static analysis and response spectrum analysis. The required Response Spectrum for main equipment of the primary coolant system of APR-1400 plant were considered to establish the enveloping response spectrum, which was applied to the seismic analysis model. The results from two seismic analysis methods were compared to show the structural adequacy of the metal insulator design against a safe shutdown earthquake. This study will form the basis for the seismic testing to support the seismic qualification of the reflective metal insulator.