• Journal of Korean Society of Steel Construction
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• v.10 no.4 s.37
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• pp.677-689
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• 1998

In relation to concentrically loaded compression, this research is to describe, analyze, and evaluate the design strength in steel stud. The similarity and difference among load and resistance factor design specification for cold-formed steel structural members (AISI), cold-formed thin gauge members and sheeting (EC3 part 1.3), and German draft (DASt-Richtlinie 016) are introduced, discussed, and systematically evaluated. Especially, the effective width and global instability problems (flexural buckling and torsional flexural buckling) are here implied in this research. The design axial strength by dual standards (AISI and EC3) is calculated and compared using the example.

• Journal of the Korean GEO-environmental Society
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• v.7 no.6
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• pp.75-88
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• 2006

This paper evaluates the feasibility of use of high-strength steel for soil-metal corrugated steel structures. Two specifications, the AASHTO(2004) and the CHBDC(2000), were compared and the scientific background of equations for the buckling stability in those specifications were investigated to figure out the governing factors for buckling strength of structures. Numerous finite element analyses for round-pipe type of soil-metal corrugated steel structures were carried out with considering the elastic-plastic relationship of a material and the geometrical non-linearity, as well as the various design variables, such as span length, depths of soil cover, section properties, tensile strength and backfill conditions. Buckling strength equation of the CHBDC(2000) is still valid and conservative for both normal and high-strength steel soil-metal corrugated steel structures, and the buckling strength increases with the use of hight-strengths steel.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.4A
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• pp.497-505
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• 2008

Corrugated steel webs resist only shear force because of the accordion effects. The shear force in the web can cause three different buckling mode: local, global, and interactive shear buckling modes. The shear behavior of the corrugated steel webs have been investigated by several researchers. However, shear buckling behavior of the corrugated webs are not clearly explained yet. And, it lead the conservative design. This paper presents shear strength of trapezoidally corrugated steel webs. A series of the tests were also conducted to verified proposed shear strength. Firstly, local, global, and interactive shear buckling equations provided by previous researchers were rearranged as a simple form considering the profiles of the existing bridges with corrugated steel webs. And, global and interactive shear buckling coefficient, and shear buckling parameter for corrugated webs were suggested in this study. Inelastic buckling strength can be determined from buckling curves based on the proposed shear buckling parameter. From the test results of this study and those of previous researchers, it can be found that suggested shear strength provides good estimation of those of trapezoidally corrugated steel webs.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.8
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• pp.2032-2037
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• 2009

The load carrying capacity of bridge structures in public use is generally evaluated without considering their actual behavioral characteristics. This study examined common errors taking place in the evaluation of load carrying capacity of bridge structures. In order to account for their current behavioral characteristics such as the boundary condition, we evaluated the load carrying capacity of a bridge in terms of axial force, which was calculated by applying deflection to the buckling equation for members with initial imperfections, and in terms of bending moment obtained from deflection.

• Proceedings of the KAIS Fall Conference
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• 2011.05a
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• pp.464-467
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• 2011

본 논문에서는 기존에 수행된 비탄성 영역 내 비지지 길이가 존재하고 균일단면을 가지는 I형 보의 좌굴 강도에 대한 해석적 이론적 연구를 토대로 변단면 I형보의 하중고 효과를 고려한 비탄성 횡-비틀림 좌굴강도에 대한 연구를 수행하였다. 유한요소해석에는 4절점 쉘요소인 S4R요소가 사용되었고, 플랜지 길이방향 비, 너비방향 비, 두께의 비로 스텝보를 나타내었으며, 집중하중을 작용시켰다. 개발된 좌굴강도 제안식은(오정재 등, 2011)과 해석결과를 하중고 효과 평가 시 큰 단면변화를 보이는 경우를 제외하고는 ${\pm}10%$의 오차범위를 나타내었다. 본 연구 결과는 다양한 형식의 I형보가 사용되는 빌딩 및 교량의 경제적이고 합리적인 설계의 근간을 제공해 줄 것이며, 향후 비탄성 횡-비틀림 좌굴강도에 대한 연구에도 많은 도움이 될 것이다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.489-492
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• 2011

장대레일 궤도의 부동구간에서 발생되는 과도한 축력은 혹서기 궤도의 좌굴을 유발시켜 주행하는 열차의 안정성을 위협할 수 있다. 궤도 제원을 제외한 압축응력과 관련된 레일온도 인자, 궤도 강성과 관련된 도상저항력, 궤도의 초기결함인 궤도틀림과 같은 인자들은 기후조건, 궤도 운영조건, 유지관리조건 등에 의해 임의적으로 변동되는 불확실성이 높은 궤도 매개변수이다. 그러므로 장대레일 궤도의 좌굴은 불확실성이 높은 현상임을 알 수 있다. 따라서 궤도 매개변수들의 불확실성 및 임의성을 합리적으로 고려하기 위해서는 확률론적 접근방법의 적용이 필수적이라 할 수 있다. 본 논문에서는 기존 본 연구진에 의해 개발된 장대레일 궤도의 좌굴확률 평가시스템을 이용하여 장대레일 축력을 산정하기 위한 필수요소인 중립온도의 확률분포 특성에 따른 좌굴 안정성을 분석하였다.

• Journal of the Geological Society of Korea
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• v.54 no.6
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• pp.657-675
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• 2018

The apparent thickening of the subducting slab in the shallow lower mantle has been attributed to slab buckling. However, the scaling laws have not been quantitatively evaluated for the buckling behavior of the subducting slab when phase transformations are considered. Thus, two-dimensional dynamic subduction experiments are formulated to evaluate the effect of phase transformations on the buckling behavior of the subducting slab. The model calculations show that the phase transformation from olivine to wadsleyite at a depth of 410 km plays an important role in the development of slab buckling; increased slab pull due to the endothermic phase transformation accelerates slab sinking in the upper mantle and the subducting slab reaches the lower mantle in a shorter time than that of the experiments without the phase transformation. However, the phase transformation from ringwoodite to perovskite plus $magnesiow{\ddot{u}}stite$ at a depth of 660 km retards slab sinking into the lower mantle and the subducting slab tends to be accumulated in the transformation (transition) zone. Buckling analyses show that the scaling laws predict the buckling amplitude and period of the subducting slab with small relative errors even if the phase transformations are considered. The universal phenomenon of the slab buckling can explain apparent slab thickening in the shallow lower mantle and transformation zone under the subduction zones such as Java-Sunda and Northeast Japan. In addition, the buckling behavior of the subducting slab may be related to the periodic compressions and extensions in the Cretaceous Gyeongsang basin.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.148.1-148.1
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• 2005

• Journal of Korean Society of Steel Construction
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• v.26 no.6
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• pp.549-558
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• 2014

Buckling restrained braces(BRBs) developed as a seismic protection element, hysteretic damper, have been investigated in America and Japan mainly. BRBs are composed of a steel core and concrete-filled steel casing. It is one of the major causes of drop in productivity to fill the steel casing with concrete. To improve this problem, the BRB is introduced in which the steel core is restrained with a pair of semicircular springs. In this paper, the numerical and analytical investigation about the desirable configuration for a semicircular spring is presented. Firstly, the stiffness and strength of semicircular spring is determined theoretically to buckle into a very high-order modes. Then, the required stiffness and strength are calculated under the practical design conditions and considered as reference values to find a proper configuration. The material strength and thickness of semicircular spring are chose from the finite element analysis for 5 semicircular springs with varying height. Finally, the nonlinear buckling analysis of BRB with proper semicircular springs shows that the bucking strength of the whole BRB is very similar to the strength of steel core with length between semicircular springs.

• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.191-196
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• 2015

해상 pedestal 크레인은 각종 운송물을 선박에 싣거나 내리는 해상 운송에 필수적인 장비이다. 따라서 구조적 안전성을 가지는 크레인 설계가 요구된다. 그의 일환으로 수행된 '해상 pedestal 크레인의 설계 개선을 위한 연구'에서는 기존 크레인의 기초 설계에 대해서 구조적 안전성올 평가하여 개선 방안을 제시하였다. 또한 좌굴 안정성 향상을 위한 보강재 설계를 수행하였다. 하지만 상세설계 관점에서 미비한 점이 있어 이를 보완할 필요성이 있다. 안전성 평가를 위해 필요한 응력을 계산하기 위해 EDISON-CSD프로그램을 통해 유한요소모델 해석을 활용한 구조해석을 수행하였다. 효율적인 해석을 위해 상세설계에 필요한 부분영역을 선택하여 모델링 하였으며 전체영역에서의 해석 결과 값을 등가 힘, 등가 모멘트로 환산하여 경계조건으로 부여하였다. 보강재간의 교차점 형상이 안전성에 미치는 영향을 보기위해 stiffener와 diaphragm의 교차점 형상(반원, 정사각형, 사다리꼴)에 따라 안전성 평가를 수행하였고, 안전 여유의 유효한 차이를 보이지 않음을 확인하였다. 평가에 필요한 응력계산을 위해 또한 Diaphragm의 좌굴에 대한 영향을 고려하기 위해 설계 규격 DNV-RP-201 8장(Buckling of girders)을 분석하였고, 안전성 평가에 반영하였다. 또한 실제 현장에서 보편적으로 사용되는 angle 형상 stiffener의 치수 도출을 위해 최적설계를 수행하였고, 모든 설계 제한조건을 만족하면서 최소의 무게를 가지는 합리적인 치수를 도출하였다.