• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2007년도 정기 학술대회 논문집
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• pp.771-776
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• 2007

Widespread propagation of failure can be triggered by localized damage to a structure because of fires, impact and explosion etc. In this paper, the progressive collapse analysis program is developed to automatically check the failed members and construct the modified structural model at each step. OpenSees, that is widely used in many research groups, was used for the developed progressive collapse analysis control program. The control program developed in this study automatically computes the damage indices of all the structural members and performance a progressive collapse analysis after the first failed member is selected. Using the developed program, we compared the progressive collapse behaviors of the example structures considering dynamic effects or not, and the difference of progressive collapse mechanism according to the modeling method of the failed members.

• 대한조선학회논문집
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• 제52권1호
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• pp.52-60
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• 2015

In the present study, an evaluation method for progressive failure of composite laminates has been proposed based on Puck's failure criterion and damage mechanics. The initial failure (or initiation of crack/delamination) has been assessed using Puck's failure criterion, and the progressive failure (or growth of crack/delamination) has been evaluated using fiber- and matrix-dependent damage variables. Based on Puck's failure criterion-damage mechanics coupling theories, the ABAQUS user-defined subroutine UMAT has been developed in order to analyze the progressive failure of glass/carbon fiber-reinforced composite laminates efficiently. In addition, the developed subroutine has been applied to progressive failure problem of industrial composite laminates, and the analysis results has been compared to experimental results which have been already reported in publications. It was confirmed that the simulation results were coincided well with the reported composite failure results.

• 한국항공우주학회지
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• 제47권4호
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• pp.256-265
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• 2019

본 논문에서는 평직물 CFRP로 제작한 직교 격자 쉘의 굽힘 하중에 의한 점진적 손상 연구를 수행하였다. 직교 격자는 복합재 바닥면과 함께 경화하여 제작하였다. 굽힘을 받는 직교 격자 쉘의 점진적 손상 해석은 Hashin-Rotem 파손 기준과 Matzenmiller-Lubliner-Taylor (MLT) 모델으로 비선형 유한요소법을 이용하여 수행하였다. 또한, 직교 격자 쉘에 대한 3점 굽힘 시험을 수행하였으며, 시험 결과와 해석 결과를 비교하였다. 변형률과 변위에 대한 시험과 해석 결과는 유사하게 나타났다. 손상 영역은 점진적 손상 해석으로 예측하였으며, 육안 검사와 초음파 비파괴 검사를 통해 측정한 결과와 비교하였다.

• Structural Engineering and Mechanics
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• 제43권5호
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• pp.657-678
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• 2012

The mismatch of ply orientations in composite laminates can cause high interlaminar stress concentrations near the free edges. Evaluation of these interlaminar stresses and their role in the progressive damage analysis of laminates is desirable. Recently, the authors developed a new method to relate the physically based micromechanics approach with the meso-scale CDM considering matrix cracking and induced delamination. In this paper, the developed method is applied for the analysis of edge effects in various angle-ply laminates such as $[10/-10]_{2s}$, $[30/-30]_{2s}$ and $[45/-45]_{2s}$ and comparing the results with available traditional CDM and experimental results. It is shown that the obtained stress-strain behaviors of laminates are in good agreement with the available experimental results and even in better agreement than the traditional CDM results. Variations of the stresses and stiffness components through the laminate thickness and near the free edges are also computed and compared with the available CDM results.

• Earthquakes and Structures
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• 제5권3호
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• pp.277-296
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• 2013

Margin of safety against potential of progressive collapse is among important features of a structural system. Often eccentricity in plan of a building causes concentration of damage, thus adversely affects its progressive collapse safety margin. In this paper the progressive collapse of symmetric and asymmetric 3-story reinforced concrete ordinary moment resisting frame buildings subjected to the earthquake ground motions are studied. The asymmetric buildings have 5%, 15% and 25% mass eccentricity. The distribution of the damage and spread of the collapse is investigated using nonlinear time history analyses. Results show that potential of the progressive collapse at both stiff and flexible edges of the buildings increases with increase in the level of asymmetry in buildings. It is also demonstrated that "drift" as a more easily available global response parameter is a good measure of the potential of progressive collapse rather than much difficult-to-calculate local response parameter of "number of collapse plastic hinges".

• Composites Research
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• 제32권5호
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• pp.258-264
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• 2019

본 논문에서는 Hashin 파손 기준식과 crack band 모델이 접목된 손상변수를 이용하여 점진적파손해석 방법이 개발되었다. 파손기준식을 이용하여 파손의 개시 유무가 판단된다. 파손이 개시된 경우에는 각 파손모드(섬유 인장/압축, 기지 인장/압축)에서 손상변수가 선형 열화 거동에 따라 계산되고, 손상강성행렬을 계산하는데 사용된다. 손상강성행렬은 손상된 재료에 반영되고, 계산된 손상강성행렬을 이용하여 재료의 완전한 파괴를 의미하는 손상변수가 1인 시점이 되기까지 점진적 파손해석이 계속해서 반복적으로 수행된다. 일련의 과정들은 상용해석프로그램인 ABAQUS에 사용자 정의 부프로그램을 이용하여 수행되었다. 제안된 점진적파손해석 도구의 검증을 위하여, 원공을 가진 복합재료 적층판의 시험 결과와 비교를 수행하였으며, 시험 중 디지털 이미지 상관법을 이용하여 획득한 변형률 거동과 해석을 통해 획득한 변형률 거동을 비교하였다. 제안된 해석결과는 시험 결과와 비교하여 유효한 일치를 보였다.

• Nuclear Engineering and Technology
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• 제33권6호
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• pp.566-584
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• 2001

In this paper, the progressive deformation and the creep-fatigue damage for the conceptually designed reactor internals of KALIMER(Korea Advanced Liquid MEtal Reactor) are carried out by using the elastic analysis method in the RCC-MR code for normal operating conditions including the thermal load, seismic load (OBE) and dead weight. The maximum operating temperature of this reactor is 53$0^{\circ}C$ and the total service lifetime is 30 years. Thus, the time- dependent creep and stress-rupture effects become quite important in the structural design. The effects of the thermal induced membrane stress on the creep-fatigue damage are investigated with the risk of the elastic follow-up. To calculate the thermal stress, detailed thermal analyses considering conduction, convection and radiation heat transfer mechanisms are carried out with the ANSYS program. Using the results of the elastic analysis, the progressive deformation and creep-fatigue damages are calculated step by step using the RCC-MR in detail. This paper ill be a very useful guide for an actual application of the high temperature structural design of the nuclear power plant accounting for the time-dependent creep and stress-rupture effects.

• Steel and Composite Structures
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• 제21권3호
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• pp.553-571
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• 2016

The progressive collapse potential of steel moment framed structures due to abrupt removal of a column is investigated based on the energy principle. Based on the changes of component's internal energy, this paper analyzes structural member's sensitivity to abrupt removal of a column to determine a sub-structure resisting progressive collapse. An energy-based structural damage index is defined to judge whether progressive collapse occurs in a structure. Then, a simplified beam damage model is proposed to analyze the energies absorbed and dissipated by structural beams at large deflections, and a simplified modified plastic hinges model is developed to consider catenary action in beams. In addition, the correlation between bending moment and axial force in a beam during the whole deformation development process is analyzed and modified, which shows good agreement with the experimental results.

• Earthquakes and Structures
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• 제12권5호
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• pp.529-541
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• 2017

According to the definition, progressive collapse could occur due to the initial partial failure of the structural members which by spreading to the adjacent members, could result in partial or overall collapse of the structure. Up to now, most researchers have investigated the progressive collapse due to explosion, fire or impact loads. But new research has shown that the seismic load could also be a factor for initiation of the progressive collapse. In this research, the progressive collapse capacity for the 5 and 15-story steel special moment resisting frames using push-down nonlinear static analysis, and nonlinear dynamic analysis under the gravity loads specified in the GSA Guidelines, were studied. After identifying the critical members, in order to investigate the seismic progressive collapse, the 5-story steel special moment resisting frame was analyzed by the nonlinear time history analysis under the effect of earthquakes with different characteristics. In order to account for the initial damage, one of the critical columns was weakened at the initiation of the earthquake or its Peak Ground Acceleration (PGA). The results of progressive collapse analyses showed that the potential of progressive collapse is considerably dependent upon location of the removed column and the number of stories, also the results of seismic progressive collapse showed that the dynamic response of column removal under the seismic load is completely dependent on earthquake characteristics like Arias intensity, PGA and earthquake frequency contents.

• 콘크리트학회논문집
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• 제26권5호
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• pp.599-606
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• 2014

초고층 건물의 연쇄붕괴는 큰 피해를 발생시키므로 초고층 건물의 설계 단계에서 반드시 고려해야할 사항이다. 유한요소법을 이용한 초고층 건물의 연쇄붕괴 해석은 해석 시간이 지나치게 많이 소요되어 사실상 불가능하다고 할 수 있다. 본 논문에서는 유한 요소법의 대안으로 응용 요소법을 이용한 연쇄붕괴 해석의 유용성을 살펴보았다. 초고층 건물의 연쇄붕괴 해석을 위하여 규모 축소 모델링 방안을 제안하였다. 제안한 규모 축소 모델링 방안은 폭파하중의 직접적인 피해를 받는 부분만 해석모델에 포함하고 제외되는 나머지 부분의 질량과 전달하중 그리고 강성은 하나의 층에 집중시키는 방법이다. 20층 고층 철근콘크리트 건물에 대한 전체 모델과 축소된 모델을 세 가지 연쇄붕괴 시나리오에 대하여 연쇄붕괴 해석을 수행하고 그 결과를 비교하였다. 축소 모델은 전체 모델과 유사한 연쇄붕괴 양상을 보여 주지만 소요된 시간은 전체 모델의 약30%로 줄일 수 있었다. 본 논문에서 제안된 연쇄붕괴 해석 방안은 비정상 하중에 의한 초고층 건물의 연쇄붕괴 해석에 유용하게 사용될 수 있다.