• 전산구조공학
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• 제23권1호
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• pp.41-48
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• 2010

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2005년도 춘계학술발표회
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• pp.815-816
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• 2005

• 한국강구조학회 논문집
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• 제19권4호
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• pp.383-393
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• 2007

본 논문에서는 비선형 유한요소해석을 기초로 기둥이 손실된 철골모멘트골조의 2경간 보 모멘트-축인장력 상호작용의 모형화 방안을 제안하였다. 본 목적을 위해 기둥이 손실된 2경간 부분골조 모델을 구성한 후 보스팬길이 대 보춤 비 및 보 사이즈를 변수로 하여 재료적/기하학적 비선형이 고려된 유한요소해석을 수행하였다. 비선형 해석을 통하여 보스팬길이 대 보춤 비가 보의 현수작용 발현에 가장 지배적인 요소임을 확인하였다. 해석결과를 토대로 초기 탄성거동에서부터 현수작용에 이르기까지의 보의 현회전각-수직저항력 관계를 일련의 선형 모델로서 근사화하는 방안을 제안하였다. 아울러, 본 연구에서 제안한 방안을 에너지평형법과 결합하여 철골모멘트골조의 비선형 정적 연쇄붕괴해석 및 설계에 편리하게 활용될 수 있음을 예시하였다.

• 한국자동차공학회논문집
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• 제6권3호
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• pp.54-62
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• 1998

In this study, collapse behavior of frame composed of thin-walled rectangular tube is investigated. Considering the collapse of frame, the bending and compression members undergo large deformation. The stiffness of the compound element is obtained from analytical moment-rotation relationship and approximated load-deflection relationsh- ip of thin-walled rectangular tube. A computer program is developed for the large deformation analysis of frame. An incremental displacement method is used in the program and at each incremental stage, the stiffness matrix of the total structure is checked with the state of each element for bending and compression.

• Structural Engineering and Mechanics
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• 제13권1호
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• pp.35-52
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• 2002

It was shown in the previous study (Lee and Bertero 1993) that incremental collapse can lead to the exhaustion of the plastic rotation capacity at critical regions in a structure when subjected to the number of load cycles and load intensities as expected during maximum credible earthquakes and that this type of collapse can be predicted using the shakedown analysis technique. In this study, a minimum-weight design methodology, which takes into account not only the prevention of this incremental collapse but also the requirements of the serviceability limit states, is proposed by using the shakedown analysis technique and a nonlinear programming algorithm (gradient projection method).

• Structural Engineering and Mechanics
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• 제60권5호
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• pp.761-779
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• 2016

Design of safe structures with resistance to progressive collapse is of paramount importance in structural engineering. In this paper, an efficient optimization technique is used for optimal design of steel moment frames subjected to progressive collapse. Seismic design specifications of AISC-LRFD code together with progressive collapse provisions of UFC are considered as the optimization constraints. Linear static, nonlinear static and nonlinear dynamic analysis procedures of alternate path method of UFC are considered in design process. Three design examples are solved and the results are discussed. Results show that frames, which are designed solely considering the AISC-LRFD limitations, cannot resist progressive collapse, in terms of UFC requirements. Moreover, although the linear static analysis procedure needs the least computational cost with compared to the other two procedures, is the most conservative one and results in heaviest frame designs against progressive collapse. By comparing the results of this work with those reported in literature, it is also shown that the optimization technique used in this paper significantly reduces the required computational effort for design. In addition, the effect of the use of connections with high plastic rotational capacity is investigated, whose results show that lighter designs with resistance to progressive collapse can be obtained by using Side Plate connections in steel frames.

• Steel and Composite Structures
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• 제26권5호
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• pp.549-556
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• 2018

Progressive building collapse occurs when failure of a structural component leads to the failure and collapse of surrounding members, possibly promoting additional failure. Global system collapse will occur if the damaged system is unable to reach a new static equilibrium configuration. The most common type of primary failure which led to the progressive collapse phenomenon, is the sudden removal of a column by various factors. In this study, a method is proposed to prevent progressive collapse phenomena in structures subjected to removal of a single column. A vierendeel peripheral frame at roof level is used to redistribute the removed column's load on other columns of the structure. For analysis, quasi-static approach is used which considers various load combinations. This method, while economically affordable is easily applicable (also for new structures as well as for existing structures and without causing damage to their architectural requirements). Special emphasis is focused on the evolution of vertical displacements of column removal point. Even though additional stresses and displacements are experienced by removal of a structural load bearing column, the proposed method considerably reduces the displacement at the mentioned point and prevents the collapse of the structural frame.

• Earthquakes and Structures
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• 제9권3호
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• pp.639-656
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• 2015

Seismic isolation devices are commonly used to mitigate damages caused by seismic responses of structures. More damages are created due to progressive collapse in structures. Therefore, evaluating the impact of the isolation systems to enhance progressive collapse-resisting capacity is very important. In this study, the effect of lead rubber bearing isolation system to increase the resistance of structures against progressive collapse was evaluated. Concrete moment resisting frames were used in both the fixed and base-isolated model structures. Then, progressive collapse-resisting capacity of frames was investigated using the push down nonlinear static analysis under gravity loads that specified in GSA guideline. Nonlinear dynamic analysis was performed to consider dynamic effects column removal under earthquake. The results of the push down analysis are highly dependent on location of removal column and floor number of buildings. Also, seismic isolation system does not play an effective role in increasing the progressive collapse-resisting capacities of structures under gravity loads. Base isolation helps to localize failures and prevented from spreading it to intact span under seismic loads.

• Nuclear Engineering and Technology
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• 제49권1호
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• pp.254-266
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• 2017

Finite-element analysis based on elastic-perfectly plastic material was conducted to examine the influence of structural deformations on collapse loads of circumferential through-wall critically cracked $90^{\circ}$ pipe bends undergoing in-plane closing bending and internal pressure. The critical crack is defined for a through-wall circumferential crack at the extrados with a subtended angle below which there is no weakening effect on collapse moment of elbows subjected to in-plane closing bending. Elliptical and semioval cross sections were postulated at the bend regions and compared. Twice-elastic-slope method was utilized to obtain the collapse loads. Structural deformations, namely, ovality and thinning, were each varied from 0% to 20% in steps of 5% and the normalized internal pressure was varied from 0.2 to 0.6. Results indicate that elliptic cross sections were suitable for pipe ratios 5 and 10, whereas for pipe ratio 20, semioval cross sections gave satisfactory solutions. The effect of ovality on collapse loads is significant, although it cancelled out at a certain value of applied internal pressure. Thinning had a negligible effect on collapse loads of bends with crack geometries considered.

• Structural Engineering and Mechanics
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• 제83권4호
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• pp.563-576
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• 2022

This study aimed to evaluate the progressive collapse potential of buildings designed using conventional design codes for the merchant occupancy classification and subjected to a sudden column failure. For this purpose, three reinforced concrete buildings having different story numbers were designed according to the seismic design recommendations of TSCB-2019. Later on, the buildings were analyzed using the GSA-2016 and UFC 4-023-03 to observe their progressive collapse responses. Three columns were removed independently in the structures from different locations. Nonlinear dynamic analysis method for the alternate path direct design approach was implemented for the design evaluation. The plasticity of the structural members was simulated by using nonlinear fiber hinges. The moment, axial, and shear force interaction on the hinges was considered by the Modified Compression Field Theory. Moreover, an existing experimental study investigating the progressive collapse behavior of reinforced concrete structures was used to observe the validation of nonlinear fiber hinges and the applied analysis methodology. The study results deduce that a limited local collapse disproportionately more extensive than the initial failure was experienced on the buildings designed according to TSCB-2019. The mercantile structures designed according to current seismic codes require additional direct design considerations to improve their progressive collapse resistance against the risk of a sudden column loss.