• Earthquakes and Structures
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• 제11권2호
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• pp.217-243
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• 2016

The linear and nonlinear seismic responses of steel buildings with perimeter moment resisting frames and welded connections (WC) are estimated and compared with those of buildings with post-tensioned connections (PC). Two-dimensional (2D) and three-dimensional (3D) structural representations of the buildings as well as global and local response parameters are considered. The seismic responses and structural damage of steel buildings with PC may be significantly smaller than those of the buildings with typical WC. The reasons for this are that the PC buildings dissipate more hysteretic energy and attract smaller inertia forces. The response reduction is larger for global than for local response parameters. The reduction may significantly vary from one structural representation to another. One of the main reasons for this is that the energy dissipation characteristics are quite different for the 2D and 3D models. In addition, in the case of the 3D models, the contribution of each horizontal component to the axial load on an specific column may be in phase each other during some intervals of time, but for some others they may be out of phase. It is not possible to observe this effect on the 2D structural formulation. The implication of this is that 3D structural representation should be used while estimating the effect of the PC on the structural response. Thus, steel frames with post-tensioned bolted connections are a viable option in high seismicity areas due to the fact that brittle failure is prevented and also because of their reduced response and self-centering capacity.

• 한국전산구조공학회논문집
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• 제24권4호
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• pp.421-428
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• 2011

국내 토목분야의 건설산업에서는 비효율적인 의사소통으로 인하여 발생하는 업무전환 단계에서의 정보누락 및 그로 인한 비용손실 등의 문제점을 해소시키기 위한 획기적인 해결책으로 BIM의 도입이 대두되고 있다. BIM은 구조물의 생애주기 전 단계에서 발생되는 모든 정보들을 3차원 파라메트릭 CAD와 연계된 3차원 정보모델을 통하여 관리하여 정보활용의 효율성을 극대화시킨다. 본 논문에서는 BIM기반의 교량건설 프로젝트의 구조설계 업무에서 사용할 목적으로 강상자형 교량의 3차원 정보모델을 활용한 내진해석 프로세스를 제안하였다. 또한 3차원 정보모델의 속성정보들이 구조적 데이터를 내재할 수 있도록 하기 위하여 3차원 모델링작업이 구조설계 업무를 통하여 결정되는 정보들을 활용하여 이루어질 수 있도록 하는 프로세스를 제안하였다. 제시된 프로세스는 현재 건설이 진행 중인 강상자형 교량을 적용하여 구성하였다. 또한 프로세스를 적용하여 내진해석의 최종 산출물인 내진계산서의 도출이 가능하다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2008년도 정기 학술대회
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• pp.573-578
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• 2008

Finite element analysis of impact response of a motorcycle helmet is presented in this paper. The finite element LS-DYNA3D code is used to simulate the impact response of the helmet including of plastic shell, foam liner, and magnesium headform. Since the maximum accelerations at center of gravity of the headform obtained by numerical analysis and experiment agree well, the numerical simulation is proved to be valid.

• Structural Engineering and Mechanics
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• 제61권3호
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• pp.407-417
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• 2017

RC shear walls are considered one of the main lateral resisting members in buildings. In recent years, FRP has been widely utilized in order to strengthen and retrofit concrete structures. A number of experimental studies used CFRP sheets as an external bracing system for retrofitting of RC shear walls. It has been found that the common mode of failure is the debonding of the CFRP-concrete adhesive material. In this study, behavior of RC shear wall was investigated with three different micro models. The analysis included 2D model using plane stress element, 3D model using shell element and 3D model using solid element. To allow for the debonding mode of failure, the adhesive layer was modeled using cohesive surface-to-surface interaction model at 3D analysis model and node-to-node interaction method using Cartesian elastic-plastic connector element at 2D analysis model. The FE model results are validated comparing the experimental results in the literature. It is shown that the proposed FE model can predict the modes of failure due to debonding of CFRP and behavior of CFRP strengthened RC shear wall reasonably well. Additionally, using 2D plane stress model, many parameters on the behavior of the cohesive surfaces are investigated such as fracture energy, interfacial shear stress, partial bonding, proposed CFRP anchor location and using different bracing of CFRP strips. Using two anchors near end of each diagonal CFRP strips delay the end debonding and increase the ductility for RC shear walls.

• International Journal of Concrete Structures and Materials
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• 제10권2호
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• pp.189-203
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• 2016

This paper investigates on the use of advanced optical measurement methods, i.e. 3D coordinate measurement machines (3D CMM) and stereo-vision digital image correlation (3D DIC), for the mechanical analysis of shear deficient prestressed concrete members. Firstly, the experimental program is elaborated. Secondly, the working principle, experimental setup and corresponding accuracy and precision of the considered optical measurement techniques are reported. A novel way to apply synthesised strain sensor patterns for DIC is introduced. Thirdly, the experimental results are reported and an analysis is made of the structural behaviour based on the gathered experimental data. Both techniques yielded useful and complete data in comparison to traditional mechanical measurement techniques and allowed for the assessment of the mechanical behaviour of the reported test specimens. The identified structural behaviour presented in this paper can be used to optimize design procedure for shear-critical structural concrete members.

• 항공우주시스템공학회지
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• 제16권6호
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• pp.64-73
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• 2022

페어링은 상용차가 주행 시 전면부에서 발생하는 유동박리의 저항을 제어하여 상용차 공기 저항력을 감소시키는 장치이다. 본 연구에서는 랭킨 반체 이론을 적용하여 3D페어링 형상을 설계하고 공력 해석을 통해 설계 결과를 검증하였다. 그리고 페어링의 구조적 안전성을 위해 상용차 과속조건과 돌풍 조건을 함께 고려하여 공력하중을 도출하였다. 이러한 공력 해석 결과를 기반으로 유리섬유/에폭시 복합재료를 적용하여 안전계수 3을 만족하는 페어링 구조 설계를 수행하였다. 최종 본 연구에서 가장 경량화된 페어링의 구조 해석을 수행하여 구조 안전성이 확인되었다.

• 한국기계가공학회지
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• 제20권2호
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• pp.80-85
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• 2021

In the fourth industrial revolution, the demand for metal three-dimensional (3D) printing technology is rapidly increasing. Metal 3D printing is an efficient method for manufacturing products because the method reduces material waste compared to subtractive manufacturing. In addition, products with complex shapes, such as turbine blades, can be easily produced using metal 3D printing because the method offers a high degree of freedom. However, due to the long production time of metal 3D printing, mass production is impossible, and post-processing is necessary due to its low precision. Therefore, it is necessary to develop a new hybrid process that can efficiently process metals and to develop a metal 3D-printing-based hybrid processing system technology to secure high processing precision and manufacture complex shapes. In this study, the structural stability of a metal 3D printer based hybrid machining center was analyzed through structural analysis before its development. In addition, we proposed a design modification that can reduce the weight and increase the stiffness of the hybrid machining center by performing shape lightning based on the structural analysis results.

• Structural Engineering and Mechanics
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• 제5권6호
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• pp.743-754
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• 1997

A three-dimensional constitutive modeling for reinforced concrete is presented for finite element nonlinear analysis of reinforced concrete. The targets of interest to the authors are columns confined by lateral steel hoops, RC thin shells subjected to combined in-plane and out-of-plane actions and massive structures of three-dimensional (3D) extent in shear. The elasto-plastic and continuum fracture law is applied to pre-cracked solid concrete. For post cracking formulation, fixed multi-directional smeared crack model is adopted for RC domains of 3D geometry subjected to monotonic and reversed cyclic actions. The authors propose a new scheme of decomposing stress strain fields into sub-planes on which 2D constitutive laws can be applied. The proposed model for 3D reinforced concrete is experimentally verified in both member and structural levels under cyclic actions.

• 건축구조
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• 제13권1호
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• pp.59-68
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• 2006

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2007년도 정기 학술대회 논문집
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• pp.451-456
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• 2007

A finite element analysis and experiment study of a motorcycle helmet are presented in this paper. The finite element LS-DYNA3D code is used to analyze the helmet. The test specimen, instruments, and setup procedures are described. Since the displacements and Von-Mises stresses obtained by numerical analysis and experiment agree well, the numerical simulation is proved to be valid.