• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.650-654
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• 1995

In this study, in order to measure energy-absorbing charactistics in collapse test of CFRP thin-walled laminates and interpretate the cause of decreasing age when collapse test is carried out under the environments of high temperatures and hygrothermals, the moisture absorbing behavior according to the variety of orientation angel is observed and collapse characteristics is compared with the influence of high temperatures and hygrothermals. Especially, we supposed to clearly understand reationship between collapse characteristics in proportion to the variety of orientation angel and moisture absorbing. The value of the maximum loading, mean loading,rate of energy absorption energy per unit volume and mass in CFRP thin-walled laminates on the high temperatures and hygrothermals is measured lower than under no moisture absorbing. The maximum collapse loading in dynamic impact test is taken measurement lower than in static collapse test regarding compared with collapse characteristics conformity with the variety of the CFRP circular laminates in high temperatures and hygrothermals. But the absorbed energy per unit mass and volume is almost same and the biggest amount of energy is shown in the CFRP circular laminates with orientation angel of 15 .deg.. Therefore, in the case of use to CFRP circular laminates with axisymmetric mode, CFRP thin-walled structal members with orientation angel of 10 .deg. , 15 . deg. are generally useful.

• 한국안전학회지
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• 제13권2호
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• pp.30-38
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• 1998

In this study, in order to measure energy-absorbing characteristics in impact test of CFRP thin-walled laminates and interpret the cause of decreasing age when collapse test is carried out under the environments of high temperatures and hygrothermals, the moisture absorbing behavior according to the variety of orientation angle is observed and impact collapse characteristics of no moisture absorbing status is compared with that under the environments of high temperatures and hygrothermals. Especially, we try to obtain quantitative design data to develop CFRP thin-walled laminates with energy characteristics of optimum impact absorbing. The value of the maximum loading, mean loading, rate of energy absorption energy per unit volume and mass in CFRP thin-walled laminates on the high temperatures and hygrothermals is measured much lower than under no moisture absorbing. The maximum collapse loading in dynamic impact test is taken measurements lower than in static collapse test CFRP circular laminates in high temperatures and hygrothermals. But the absorbed energy per unit mass and volume is almost same each other and the biggest amount of energy is shown in CFRP circular laminates with orientation angle of $15^{\circ}$. Therefore, in the case of using CFRP circular laminates with axisymmetric mode, CFRP thin-walled structural members with orientation angle of $10^{\circ}$, $15^{\circ}$ has generally best condition.

• Structural Engineering and Mechanics
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• 제81권2호
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• pp.231-242
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• 2022

Numerical solutions for the linear buckling behavior of thin-walled circular hollow section members (CHS) with and without longitudinal stiffeners are presented using the semi-analytical finite strip method (SAFSM) which is developed based on Marguerre's shallow shell theory and Kirchhoff's assumption. The formulation of 3-nodal line finite strip is presented. The CHS members subjected to uniform axial compression, uniform bending, and combination of compression and bending. The buckling behavior of CHS is investigated through buckling curves which relate buckling stresses to lengths of the member. Effects of longitudinal stiffeners are studied with the change of its dimensions, position, and number.

• Steel and Composite Structures
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• 제31권2호
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• pp.201-216
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• 2019

This scientific paper provides a theoretical, numerical and experimental analysis of local stability of axially compressed columns made of thin-walled rectangular concrete-filled steel tubes (CFSTs), with the consideration of initial geometric imperfections. The work presented introduces the theory of elastic critical stresses in local buckling of rectangular wall members under uniform compression. Moreover, a numerical calculation method for the determination of the critical stress coefficient is presented, using a differential equation for a slender wall with a variety of boundary conditions. For comparison of the results of the numerical analysis with those collected by experiments, a new model is created to study the behaviour of the composite members in question by means of the ABAQUS computational-graphical software whose principles are based on the finite element method (FEM). In modelling the analysed members, the actual boundary and loading conditions and real material properties are taken into account, obtained from the experiments and material tests on these members. Finally, the results of experiments on such members are analysed and then compared with the numerical values. In conclusion, several recommendations for the design of axially compressed composite columns made of rectangular concrete-filled thin-walled steel tubes are suggested as a result of this comparison.

• 한국강구조학회 논문집
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• 제21권6호
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• pp.619-626
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• 2009

저층 장스팬 철골프레임에는 강재절감을 위해 휨모멘트 저항에 극대화한 판폭 두께비가 큰 단면 부재를 사용하고 있다. 한편, 외부환경에 노출된 강부재는 수년간을 걸쳐 부식이 진행된다. 부식에 의한 단면결손에 따른 내력감소는 판폭두께비가 큰 부재의 경우가 판폭두께비가 작은 부재에 비하여 상대적으로 크다. 또한, 부식에 의한 압축측 플랜지 및 웨브 판두께의 감소(판폭두께비 증가)에 의한 한계상태 영역이 변경될 여지도 있다. 본 논문에서, 국내 장스팬 철골프레임을 대상으로 판폭두께비가 큰 단면에 대해서 부식진행정도에 따른 모멘트-회전각관계, 초기강성, 최대내력, 최대내력이후 강성 및 에너지흡수능력에 대해서 평가를 행하였다.

• 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.

• 한국자동차공학회논문집
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• 제5권3호
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• pp.1-14
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• 1997

In this paper, collapse test of thin-walled structural member widely used for automobiles is carried out under static compression load to observe the effects of cross- sectional shape and material on the energy absorbing capacity in the viewpoint of cras- hworthiness. Specimens tested consist of two sorts(Aluminium, CFRP) and configur- ations(Circular, Square) with variation in thickness. Also, comparisons of Al circular and square specimens are made to find the influence of difference in shape on the energy absorbing capability according as the thickness of specimen varies.

• Structural Engineering and Mechanics
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• 제9권6호
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• pp.541-555
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• 2000

Pultruded cross-sections are always thin-walled due to constraints in the manufacturing process. Thus, the buckling strength determines the overall strength of the member. The elastic buckling of pultruded angle sections subjected to direct compression is studied. The lateral-torsional buckling, very likely to appear in thin-walled cross-sections, is investigated. Plate theory is used to allow for cross-sectional distortion. Shear effects and bending-twisting coupling are accounted for in the analysis because of their significant role. A simplified approach for determining the maximum load of equal leg angle sections under compression is presented. The analytical results obtained in this study are compared to the manufacturer's design guidelines for compression members as well as with the design specifications for steel structural members. Experimental results are obtained for various length specimens of pultruded angle sections. The results presented in this paper correspond to actual pultruded equal leg angle sections being used in civil engineering structures.

• 대한토목학회논문집
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• 제11권2호
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• pp.1-14
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• 1991

평면내에서의 비틀림에 대한 강성도를 갖는 3절점 삼각형 shell요소를 사용하여 박판으로 이루어진 곡석 또는 직선부재의 선형 탄성좌굴 해석을 위한 컴퓨터 프로그램을 개발 하였다. 판의 좌굴 해석과 보의 횡 비틈 좌굴해석을 통하여 본 프로그램의 타당성을 입증하였고, 이를 순수 휨을 받는 양단의 단순지지된 원호 아치의 좌굴해석에 적용시켜 그 결과들을 다른 연구 결과들과 비교 검토하여 보았다.

• Steel and Composite Structures
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• 제20권3호
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• pp.693-718
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• 2016

This paper presents a finite element procedure based on Bridging multi-scale method (BMM) in order to incorporate the effect of local/cross-sectional deformations (e.g., flange local buckling and web crippling) on the global behaviour of thin-walled members made of fibre-reinforced polymer composite laminates. This method allows the application of local shell elements in critical regions of an existing beam-type model. Therefore, it obviates the need for using computationally expensive shell elements in the whole domain of the structure, which is otherwise necessary to capture the effect of the localized behaviour. Consequently, highly accurate analysis results can be achieved with this method by using significantly smaller finite element model, compared to the existing methods. The proposed method can be used for composite polymer laminates with arbitrary fibre orientation directions in different layers of the material, and under various loading conditions. Comparison with full shell-type finite element analysis results are made in order to illustrate the efficiency and accuracy of the proposed technique.