The recent earthquake in Korea caused a lot of damage to reinforced concrete (RC) columns with non-seismic details. The nonlinear analysis enables predicting the hysteresis behavior of RC columns under earthquakes, but the analytical model used for the columns must be accurate and practical. This paper studied the nonlinear analysis models built into a commercial structural analysis program for the existing RC columns. The load-displacement relationships, maximum strength, initial stiffness, and energy dissipation predicted by the three analysis models were compared and analyzed. The results were similar to those tested in the order of the fiber, Pivot, and Takeda models, whereas the fiber model took the most time to build. For columns subjected to axial load, the Pivot model could predict the behavior at a similar level to that of the fiber model. Based on the above, it is expected that the Pivot model can be applied most practically for existing RC columns.

본 연구에서는 유한요소해석 D/B를 기반으로 보간식을 산출하여 개활지 폭발현상에 의해 기둥에 작용하는 폭압이력을 예측하는 모델을 개발했다. D/B 구성을 위해 7종류 기둥 너비에 대해 총 70회의 유한요소해석을 수행했다. 제안하는 방법의 성능확인을 위해, 기존에 제시된 경험식 기반의 예측식과의 비교연구를 수행했다. 또한, D/B를 구성하는 point 외의 영역에서의 예측 정확도 확인을 위 해 유한요소해석 결과와의 비교/검증 연구를 추가로 수행했다. 제안하는 방법은 기존의 경험식 기반 예측식에 비해 유한요소해석 결 과와 유사한 결과를 산출함을 확인했다.

KAERI has planned to carry out a series of dynamic tests using a shaking table and time-history analyses for a channel-type concrete shear wall to investigate its seismic performance because of the recently frequent occurrence of earthquakes in the south-eastern parts of Korea. The overall size of a test specimen is ×× 2500 mm×3500 mm×4500 mm, and it consists of three stories having slabs and walls with thicknesses of 140 mm and 150 mm, respectively. The system identification, FE model updating, and time-history analysis results for a test shear wall are presented herein. By applying the advanced system identification, so-called pLSCF, the improved modal parameters are extracted in the lower modes. Using three FE in-house packages, such as FEMtools, Ruaumoko, and VecTor4, the eigenanalyses are made for an initial FE model, resulting in consistency in eigenvalues. However, they exhibit relatively stiffer behavior, as much as 30 to 50% compared with those extracted from the test in the 1st and 2nd modes. The FE model updating is carried out to consider the 6-dofs spring stiffnesses at the wall base as major parameters by adopting a Bayesian type automatic updating algorithm to minimize the residuals in modal parameters. The updating results indicate that the highest sensitivity is apparent in the vertical translational springs at few locations ranging from 300 to 500% in variation. However, their changes seem to have no physical meaning because of the numerical values. Finally, using the updated FE model, the time-history responses are predicted by Ruaumoko at each floor where accelerometers are located. The accelerograms between test and analysis show an acceptable match in terms of maximum and minimum values. However, the magnitudes and patterns of floor response spectra seem somewhat different because of the slightly different input accelerograms and damping ratios involved.

As the damage caused by earthquakes gradually increases, seismic retrofitting for existing public facilities has been implemented in Korea. Several types of structural analysis methods can be used to evaluate the seismic performance of structures. Among them, for nonlinear dynamic analysis, the hysteresis model must be carefully applied because it can significantly affect the behavior. In order to find a hysteresis model that predicts rational behavior, this study compared the experimental results and analysis results of the existing non-seismic reinforced concrete frames. For energy dissipation, the results were close to the experimental values in the order of Pivot, Concrete, Degrading, and Takeda models. The Concrete model underestimated the energy dissipation due to excessive pinching. In contrast, the other ones except the Pivot model showed the opposite results with relatively little pinching. In the load-displacement curves, the experimental and analysis results tended to be more similar when the column axial force was applied to columns.

In this paper, for a seismic analysis of an offshore subsea manifold, Response Spectrum Analysis(RSA) and Time History Analysis(THA) were conducted under a various analysis conditions. Response spectrum and seismic design procedure have followed ISO19901-2 code. In case of THA, The response spectrum were converted into artificial earthquake history and both of Explicit and Implicit solvers were used to examine the characteristics of seismic analysis. For the verification, Various seismic analysis methods were applied on a single degree of freedom beam model and a simplified model of the actual manifold. The difference between the results of RSA and THA on the simplified manyfold model evaluated for the analysis of the actual manifold. Because THA is impossible in case of real complex structure such as a manifold, Safety of the actual manifold structure was accessed by using the RSA and the difference between the results of RSA and THA from the simplified model.

The objective of this study is to propose a simple and accurate analytical model for HSS braces. For this purpose, a physical theory model is adopted. Rectangular hollow section steel (HSS) braces are considered in this study. To accurately simulate the cyclic behavior of braces using the physical theory model, empirical equations calculating constituent parameters are implemented on the analytical model, which were proposed in the companion paper. The constituent parameters are cyclic brace growth, cyclic buckling load, and the incidence of local buckling and fracture. The analytical model proposed in this study was verified by comparing actual and simulated cyclic curves of brace specimens. It is observed that the proposed model accurately simulates the cyclic behavior of the braces throughout whole response range.

본 논문에서는 제4세대 소듐냉각고속로(Sodium-Cooled Fast Reactor)의 후보 노형으로 선정된 KALIMER-600에 대한 단순 지진해석모델을 개발하고 시간이력 지진응답해석을 수행하여 수평 면진설계(Seismic Isolation) 기술이 적용된 원자로건물의 주요기기 및 구조물에서의 지진응답 성능을 분석하였다. 개발된 단순 지진해석모델은 원자로건물, 원자로시스템, 주요 기기, 중간 열전달계통 배관, 그리고 면진장치를 포함하며 각각은 상세 유한요소해석을 통한 동특성 비교검증을 통하여 정확성을 검증하였다. 안전정지기준 0.3g의 설계인공지진 하중에 대한 시간이력 지진응답해석을 수행하여 면진설계와 비면진 설계조건에 따른 원자로 주요 부위에서의 층응답스펙트럼을 비교분석한 결과 KALIMER-600의 면진성능이 우수한 것으로 나타났다.

In this paper, various dynamic model of magnetorheological (MR) damper, is required for describing the hysteresis of MR damper and for their application are investigated to structural control. The dynamic characteristics and control effects of the modeling methods for MR dampers such as Bingham, biviscous, hysteretic biviscous, simple Bouc-Wen, Bouc-Wen with mass element, and phenomenological models are studied. Of these models, hysteretic biviscous model which is simple and describes the hysteretic characteristics, is chosen for numerical studies. The capacity of MR damper is determined as a portion of not the building weight but the lateral restoring force.

기존의 철근콘크리트 부재의 이력모델은 실험에 기초한 경험식을 사용하여 주기거동시 나타나는 강성저하를 나타내는데 중점을 두므로, 에너지소산능력을 정확히 예측할 수 없다. 최근 다양한 설계변수의 영향을 고려하여 주기거동 동안 소산하는 에너지를 정확히 계산할 수 있는 설계식이 개발되었다. 본 연구에서는 이러한 설계식에 기초하여 휨지배 부재에 대한 에너지기초이력모델(Energy-Based Hysteretic Model)을 개발하였다. 제안된 모델은 완전한 주기거동을 할 경우 실제거동과 동일한 에너지를 소산하도록 고안된 선형모델로, 주곡선(Primary Curve)과 주기곡선(Cyclic Curve)을 근간으로 하고 다섯 가지 제하/재하 규칙을 적용하여 핀칭 및 강성저하를 수반하는 주기거동을 나타낸다. 본 연구에서는 다양한 실험과의 비교를 통하여 제안된 이력모델의 정확성과 유효성을 검증하였다. 제안된 이력모델은 간단하면서도 수치해석의 적용에 용이하므로, 정적 및 동적 비선형 해석/설계 프로그램의 개발에 사용할 수 있다

지진하중파 유사한 반 복 하증에 의한 철금 콘크리 프 부재의 설제 거동을 재생키 위한 해석적인 이력 모덴블 제시하였다. 특 히 RC 샤재의 동적거동의 증요한 현상뜰언 강성서하， 강도저하 그리고 전단 영향등의 해석 모 덴 올 소개하였으며 제안된 이력모덴의 정 확성 및 사용성 동 의 평가플 위하여 설험결과 의 하 중 변위 팍선윌 과 비 j니 분 석 하였다