• Proceedings of the KSR Conference
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• 2000.11a
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• pp.374-381
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• 2000

본 논문에서는 지진 발생시, LRB가 설치된 교량의 시간이력 해석을 수행하였다 이를 위해 LRB의 비선형 거동특성을 Bi-linear로 모형화 하였으며, 기존의 방법인 등가선형으로 모형화된 해석결과와 비교하였다. 또한 LRB받침만 설치된 경우와, LRB받침과 일반탄성받침이 함께 사용된 경우를 해석하여, 받침이 혼합된 경우, 상시하중과 지진하중시 발생할 수 있는 문제점을 검토하였다. 4경간 연속교량에 적용된 해석결과를 보면, LRB만을 설치한 경우, Pot-Bearing만 설치된 경우에 .비해, 고유주기 상승과 이력감쇠에 의한 지진력의 감소와 함께, 지진력의 효과적인 분배를 볼 수 있었으며, 일반탄성받침과의 적절한 조합에 의해서도, 충분한 면진성능을 얻을 수 있었다. 또한 LRB의 등가선형 모델이 Bi-linear 모델에 비해 보수적인 해석결과를 나타내었다.

• Journal of the Earthquake Engineering Society of Korea
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• v.7 no.6
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• pp.71-80
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• 2003

Though a nonlinear time history analysis may be provided to estimate more exactly the seismic performance of building structure, approximation methods are still needed in the aspect of practicality and simplicity, In converting a multi-story structure to an equivalent SDOF system, the mode vectors of the multi-story structure are assumed as the mode shape in elastic state regardless of elastic or elastic-plastic state. However, the characteristics of displacement mode are also changed after the yielding made in the structural elements, because the structure becomes inelastic in each incremental load step. In this research, a method of converting MDOF system to ESDOF system is presented by using nonlinear displacement mode considering the mode change of structures after the yielding. Also, the accuracy and efficiency of the method of the nonlinear displacement mode method of the estimate of seismic response of Mixed Building Structures were examined by comparing the displacements of the roof level of the multi-story building structures estimated from this converted displacement response of ESDOF with the displacement of the roof level through the nonlinear dynamic analysis of the multi-story building structures subjected to an actual earthquake excitation.

• 전기의세계
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• v.45 no.2
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• pp.32-38
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• 1996

본 논문에서는 2차측이 평판형 구조를 갖는 선형유도전동기를 대상으로 하여 유한요소법을 이용한 수치해석방법과 기자력발생의 개념적인 기본단위가 되는 하나의 전류도체를 등가표면전류밀도로 치환하여 해석하는 공간고조파해석 방법[10]과, 영구자석 계자형 선형동기전동기의 공간고조파 해석방법에 대하여 소개하겠다.

• Journal of the Korea Concrete Institute
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• v.26 no.3
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• pp.351-360
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• 2014

The purpose of this research is to introduce the simplified equivalent frame model for the equivalent lateral force procedure, the response spectrum procedure and nonlinear procedure according to ASCE7-10 in order to reduce the time of performance and reasonably evaluate the effect of applying the damping system with the various conditions for the analysis and the variable. In this research, the seismic performance assessment and the design of the damping system were conducted through the nonlinear time history analysis based on the performance based seismic design in ASCE7-10 in regard to applying the damping system to apartment buildings which is lately issued. The optimal design based on the 75% of seismic base shear was performed for an apartment building. The seismic performance assessment were conducted to check the safety of the building, and the economic evaluation was performed by comparing the amount of resource for the optimal designed building with the amount of resource for the original building. In addition, hysteresis dampers was applied to the apartment building, and the suggested equivalent frame model was performed using the damping system design in ASCE7-10, then its control effects were proved in the full scale model of the apartment building which was used in this research.

• Journal of the Korean Geotechnical Society
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• v.24 no.3
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• pp.13-23
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• 2008

In a nonlinear site response analysis which is performed in time domain, small strain damping is modeled as viscous damping through use of various forms of Rayleigh damping formulations. Small strain damping of soil is known to be independent of the loading frequency, but the viscous damping is greatly influenced by the loading frequency. The type of Rayleigh damping formulation has a pronounced influence on the dependence. This paper performs a series of nonlinear analyses to evaluate the degree of influence of the viscous damping formulation on Korean soil profiles. Analyses highlight the strong influence of the viscous damping formulation for soil profiles exceeding 30 m in thickness, commonly used in simplified Rayleigh damping formulation overestimating energy dissipation at high frequencies due to artificially introduced damping. When using the full Rayleigh damping formulation and carefully selecting the optimum modes, the artificial damping is greatly reduced. Results are further compared to equivalent linear analyses. The equivalent linear analyses can overestimate the peak ground acceleration even for shallow profiles less than 20 m in thickness.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.6
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• pp.501-508
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• 2014

In this paper, a method on deducing the capacity spectrum based on nonlinear earthquake response analysis will be introduced. Damage assessment of general building draws the capacity spectrum through the Push-over analysis and the intersection point of capacity spectrum and demand spectrum is seen as performance point. Push-over analysis is the way to perform static analysis by using the equivalent static load changed from the effect of earthquake and predict the behavior of structures by earthquake. But, this method can not be taken into account in the effects of higher mode and the dynamic characteristic. Therefore, in order to calculate the capacity spectrum under dynamic properties of building. A capacity spectrum from going ahead with the nonlinear earthquake response analysis is suggested.

• Journal of the Society of Naval Architects of Korea
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• v.30 no.4
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• pp.39-45
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• 1993

In order to analyze the rolling motion of a ship in random beam waves we have used the equivalent linearization method. The quadratic nonlinear damping, the cubic and quintic nonlinear restoring moments were added to a single degree of freedom linear equation of roll motion. The irregular excitation moment was assumed to be the Gaussian white noise. The statistical characteristic of the response by the equivalent linearization method was compared with the simulation result.

• Journal of the Earthquake Engineering Society of Korea
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• v.6 no.4
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• pp.65-73
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• 2002

It has been recognized that the damage control must become a more explicit design consideration. In an effort to develop design methods based on performance it is clear that the evaluation of the nonlinear response is required. The methods available to the design engineer today are nonlinear time history analyses, monotonic static nonlinear analyses, or equivalent static analyses with simulated nonlinear influences. Some building codes propose the capacity spectrum method based on the nonlinear static analysis(pushover analysis) to determine the earthquake-induced demand given by the structure pushover curve. These procedures are conceptually simple but iterative and time consuming with some errors. This paper presents a nonlinear direct spectrum method(NDSM) to evaluate seismic performance of structures, without iterative computations, given by the structural initial elastic period and yield strength from the pushover analysis, especially for MDF(multi degree of freedom) systems. The purpose of this paper is to investigate the accuracy and confidence of this method from a point of view of various earthquakes and unloading stiffness degradation parameters. The conclusions of this study are as follows; 1) NDSM is considered as practical method because the peak deformations of nonlinear system of MDF by NDSM are almost equal to the results of nonlinear time history analysis(NTHA) for various ground motions. 2) When the results of NDSM are compared with those of NTHA. mean of errors is the smallest in case of post-yielding stiffness factor 0.1, static force by MAD(modal adaptive distribution) and unloading stiffness degradation factor 0.2~0.3.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1995.04a
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• pp.129-136
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• 1995

본 연구에서는 핵연료봉의 여러가지 모양형태에 대한 충격실험과 해석을 통해 비선형해석 code의 해석모델에 대한 검증을 수행하였다. 이 두 결과의 비교를 통해 개발된 모델은 다중 span을 갖는 보나 봉의 비선형충격해석에 충분히 사용될 수 있음을 확인하였다. 이러한 모델을 통한 비선형충격해석시 주의해야 할 점은 자유진동해석시의 고유진동수를 찾기 위한 경계조건을 정확히 하는 것이 중요하며, 또한 충격해석시의 정확한 충격등가스프링비를 결정하는 것이 중요하다.

• Journal of the Korean Geotechnical Society
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• v.33 no.12
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• pp.45-58
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• 2017

As many seismic codes for various facilities are changed into a performance based design code, demand for a reliable nonlinear response-history analysis (RHA) arises. However, the equivalent linear analysis has been used as a standard approach since 1970 in the field of site response analysis. So, the reliability of nonlinear RHA should be provided to be adopted in replace of equivalent linear analysis. In this paper, the reliability of nonlinear RHA is reviewed for a layered soil layer using Loma Prieta earthquake records in 1989. For this purpose, the appropriate way for selecting nonlinear soil models and the effect of base boundary condition for 3D analysis are evaluated. As a result, there is no significant differences between equivalent linear and nonlinear RHA. In case of 3D analysis, absorbing boundary condition should be applied at base to prevent rocking motion of the whole model.