Buckling Restrained Braces can not only express the strength considered at the time of design, but also reduce the seismic load by energy dissipation according to the plastic behavior after yield deformation of the steel core. The physical characteristics and damping effect may be different according to the buckling prevention method of the steel core by the lateral restraint element. Accordingly, in this study, To compare hysteresis characteristics, Specimen(BRB-C) filled with mortar, specimen(BRB-R) combined with a buckling restraint ring and Specimen(BRB-EP) filled with engineering plastics was fabricated, and a cyclic loading test was performed. As a result of the cyclic loading test, the maximum compressive strength, cumulative energy dissipation and ductility of each test specimen was similar. But in case of the cumulative energy dissipation and ductility, BRB-C filled with the mortar specimen showed the lowest. This is considered to be because the gap between the steel core and the reinforcing material for plastic deformation was not uniformly formed by pouring mortar around the core part.

해저 석유와 가스 탐사가 점점 더 깊은 수심으로 진행되고 있으며, 해저 파이프라인은 고압 및 고온 조건에서 작동하는 것이 일반적이다. 온도 및 압력 차이로 인하여 파이프 축 방향 힘이 축적되는 현상이 있다. 이러한 현상은 파이프라인을 구속하는 해저면 효과 때문에 파이프라인은 횡 좌굴이 발생하게 된다. 온도가 증가하는 경우 축 방향의 압축 하중이 가해지며 이 하중이 임계 수준에 도달하면 파이프가 수직방향으로 움직이게 된다. 또는 파이프라인의 구조적 완전성을 위태롭게 할 수 있는 횡 방향 좌굴이 발생하는 상황에서, 작 동 중 파이프라인의 구조적 안전함을 보장하기 위해 파이프라인의 상세 구조 강도평가가 수행되어야 한다. 본 연구에서는 해저면의 마찰 효과 및 재료의 열 수축/팽창을 고려한 비선형 구조해석을 상용 유한요소해석 프로그램인 ANSYS를 활용하여 검토하였으며, 외부충격에 의한 횡 방향 좌굴 안전성을 분석하였다. 본 연구의 결과를 통하여 수치 해석적 단순화된 분석 모델을 통하여 해저면의 효과를 고려한 조 건에서의 실제 파이프라인의 붕괴 조건을 예측할 수 있다.

Beam bracing is applied to prevent the relative displacement of the top and bottom flanges or to effectively control the twisting of the section, and the lateral stability of the beams are provided by lateral bracing, torsional bracing or a combination of both. Modular steel I-girders are laterally interconnected by torsional bracings that are installed to increase the resistance to lateral torsional buckling. In this paper, numerical parametric study was carried out by varying the crossbeam web height to examine the effects of the web torsional stiffness. Three-dimensional finite-element analysis using the commercial finite element software ABAQUS was obtained for the parametric numerical analyses of a series of feasible two-girder models, and the failure mode, lateral-torsional buckling strength and the moment-displacement behavior of the main girders was determined.

Over the years, several studies have been made for the improvement of the design criteria of stepped beams. However, studies on lateral-torsional buckling of stepped beams located at the midspan have been very limited. Hence, this study aims to evaluate the elastic lateral-torsional buckling strength of doubly symmetric singly stepped I-beam at midspan subjected to pure bending along the entire span. The I-beam measurements and specifications are in accordance with the AISC standards. For the analysis of stepped beams, the parameters α, β and γ are used. In this paper, singly stepped beams are defined as beams having an increased cross section at midspan. The unbraced length used for the simply supported stepped I-beams are 13.59m, 18.12m, and 22.65m while the parameters α, β and γ for the cross section varies from 0.167~0.333, 1.0~1.4, and 1.0~1.8, respectively. To model and perform the analysis for the I-beams, a universal finite element analysis program, ABAQUS, will be used. S4R elements will be used to model the simply supported beams and to check the accuracy of the models guide design specifications are used. The results from the finite element analysis will be shown in tables and plotted into graphs. Based from the obtained results, conclusions and new design guidelines are proposed.

This study aims to give a brief summary of the development in the series of studies that have been made regarding the lateral-torsional buckling (LTB) capacity of beam spans with increased cross section at one end, also known as singly stepped beam (SSB), and at both ends, also known as doubly stepped beam (DSB). A three-dimensional program ABAQUS was used to analyze buckling through finite element method, while a statistical regression program MINITAB was used in developing and proposing simple design equations. The following topics discussed in this study include: (1) proposed design equation that account for change in cross section of stepped beams under uniform moment; (2) proposed design equation, with a corresponding moment gradient factor equation, of stepped beams under general loading conditions; (3) proposed design equation for stepped beam with continuous top flange lateral bracing; (4) proposed design equation for monosymmetric stepped beam subjected to uniform moment and to general loading conditions; (5) effect of inelastic buckling of stepped beams subjected to pure bending and general loading conditions considering combined effects of residual stress and geometrical imperfection; and (6) determination of LTB strength of monosymmetric stepped beam by conducting destructive test of subjecting a beam to concentrated load. The summary presented provides researchers information in understanding the subject matter; moreover, this provides a meaningful contribution to futures researches.

Beam string structures(BSS) are one kind of efficient structure system because the bending moment in the beams is reduced greatly through the struts and the strings. As the struts in BSS are used as middle supports to the beam and always in compression, the buckling of the struts should be avoided. This paper investigates the lateral buckling of the struts in BSS. Firstly, the strut of a one-strut BSS is simplified into an analytical model by considering load is formulated and some special cases of the model are analyzed. Finally, the lateral buckling load of the strut is numerically examined by means of parameter studies. It is known that, because on end of the struts is jointed to the beam while the other end is connected to the strings, the buckling of the struts not only depends on the length of the struts and the stiffness of the joints, but also depends on the rise and the lateral stiffness of the beam, the layout of the strings and the number of the struts.

This study is all about the presentation of the results of the analyses made to determine the inelastic lateral torsional buckling strength of singly symmetric singly stepped I-beam with constant depth subjected to basic loading condition. A finite element program ABAQUS and a regression program MINITAB are used to analyze the simply supported singly symmetric singly stepped I-beams having singly symmetric ratio, ρ, of 0.1 to 0.9 and a Lb/h ratio of 4.5. Using the results of the analyses made, a design equation is suggested that can easily calculate the stepped beam correction factor Cist which then can be used to determine the inelastic lateral torsional buckling strength of singly symmetric singly stepped I-beams subjected to pure bending moment. Then, the results from the equation proposed are compared with the results obtained from the finite element analysis. The results obtained show acceptable results for singly stepped beams having a ρ of 0.3 to 0.9 and a very conservative result for a ρ of 0.1.

FRP Sheet와 비좌굴가새를 적용한 보-기둥 접합부의 보강효과를 평가하기 위하여 보-기둥 접합부 실험체에 축력 및 반복 횡가력을 가하여 실험을 수행하였다. 동일한 크기의 6개의 실험체를 제작하였으며 FRP Sheet의 종류 및 비좌굴 가새의 유무를 변수로 하였다. 실험체의 파괴양상 및 최대하중, 연성지수, 에너지소산능력의 측면에서 실험결과를 분석하였다. 실험결과 CFRP Sheet와 비좌굴가새를 혼용한 보강방법이 가장 우수한 성능을 나타냈다.

본 연구의 목적은 일정 축하중과 반복횡하중 하에서 탄소섬유시트와 비좌굴 가새로 보강된 보-기둥 시험체의 횡방향 거동 평가를 통하여 사용된 보강 방법의 구조적 성능을 검증하는 것이다. 세 개의 시험체를 비보강, 탄소섬유보강, 탄소섬유와 비좌굴 가새 보강 방법을 각각 적용하여 제작하였다. 변위에 따른 최대, 최소하중은 하중-변위 관계를 분석함으로써 평가되어지며, 하중과 강성의 관계는 비교구간의 유효강성 분석에 의해 평가된다. 실험의 수행 결과, 보강을 하지 않은 시험체에 비하여 보강을 적용한 시험체는 최대허용하중과 유효강성, 철근 항복 시 재하 횡하중, 변위연성비 등에서 상대적으로 우수한 성능을 보였다.

본 논문은 횡하중을 받는 냉간성형 ㄷ 형강보의 응력해석에 관해 다루고 있다. 냉간형강 보에 가해지는 각 하중 레벨에서의 응력을 계산하여 국부좌굴과 횡좌굴을 고려하여 구조해석을 실시하였다. 해석모델은 박벽보의 기본이론에 의해 유도되었으며 1차원 보요소 유한요소해석을 통하여 수치해석을 하였다. 수치해석결과는 AISI 규준과 비교되었으며, 본 연구에서 제안된 해석모델이 냉간형강보의 처짐뿐 아니라 응력도 매우 정확히 예측함을 알 수 있었다.

선체를 구성하는 판부재는 일반적으로 면내하중과 횡하중의 조합하중이 작용하게 된다. 면내하중으로서는 주로 전체적인 선체거더의 휨과 비틀림에 의한 압축하중 및 전단하중이 있다. 횡하중은 수압과 화물압력에 의해서 작용하게 된다. 이러한 하중의 요소들은 항상 동시에 작용하는 것은 아니지만 한 개 이상의 하중이 존재하고 상호작용하게 된다. 그러므로, 좀 더 합리적이고 안정적인 선박구조의 설계를 위해서는 이러한 조합하중이 선체판에 작용할 경우에 발생하게 되는 좌굴 및 최종강도거동의 상호관계를 좀 더 자세히 분석할 필요가 있다. 실제로 선체판은 슬래밍과 팬팅과 같은 충격하중을 제외하고는 상대적으로 작은 수압이 작용하게 된다. 본 연구에서는 조합하중을 받는 선체판부재의 거동에 있어서 최종한계상태 설계법에 기반을 둔 탄소성대변형 유한요소해석을 수행하였다. 본 연구에서는 압축하중과 횡하중이 판부재에 작용하였을 경우 횡하중의 크기에 따른 2차좌굴 거동의 영향을 탄소성대변형 유한요소해석(ANSYS)으로 분석하였다.

본 논문에서는 횡비틀림좌굴을 고려하는 2차 소성힌지해석법을 이용하여 3차원 강뼈대구조물의 설계기법을 개발하였다. 본 해석은 구조시스템 및 개별부재의 재료적 기하학적 비선형 거동을 고려한다. 더욱이, 종래의 2차 소성힌지해석에서 횡비틀림좌굴효과에 의한 휨강도 감소효과를 고려하지 못한 문제를 해결하였다. 강뼈대구조물의 잔류응력과 휨에 의한 비선형성 및 기하학적 불완전성에 의한 점진적인 소성화효과를 고려하는 효율적인 방법을 기술하였다. 횡비틀림좌굴효과를 고려하기 위하여 비지지장 및 단면 형상으로 구성되는 침강도 감소모델을 사용하였다. 개발된 2차 소성힌지해석법을 LRFD 설계방법과 비교함으로서 검증하였다. 예제해석을 통하여 횡비틀림좌굴효과는 2차 소성힌지해석법에 고려해야 할 중요한 요소임을 알 수 있었다. 본 해석은 실제 설계에 활용할 수 있는 효율적이고 신뢰성 있는 방법이다.

反復혜重올 받는 짧은 I 보 (Beam) 의 慣-비틀림 座때(Lateral-Torsional Buckling) 에 대한 흩윌뼈한 Parametric Study 를 逢行하여 보의 座맴現象올 좀 더 깊이 考흉하고자 한다. 有限한 비틀림햇形의 뒤틀림 (Warping) 이외에 m 少한 맺톨JTft形의 뒤틀립도 고려한 幾何學적 (完全) 非綠形의 一次7ê 보를 껴￥析的 모델 로 사용하고， 또한 金!홉의 周期的뺑性(Cyclic Plasticity) 쌓:tJJ을 보다 잘 나타내기 위해 多빼 週期的뿔性 모 덴올 Consistent Return Mapping Algorithm과 결합시켜 遭用한다. :한ì.ffI때 단방에서 아래와 갇은 여러가지 Parameter Study를 끊行함으로써 反復휴重을 받는 짧은 I 보의 함 -비블립 座며의 -압的 應홈을 ι~.흉한다 : 材料의 降ik~옳度， 降ik플래토 (Yield Plateau) , 뿔形率硬化，U-:tJJ 硬化(Kinematic Hardening) , 웰留應力， 作用倚重의 f.1端中心에 대 한 {f，í ι、率， 作用倚훌의 보 톰面에 대 한 높 이， 作用혜훨의 보 김이방향의 位置， 보 뻐f 面의 置f!{， 作用倚重으로 부터 멀리 떨어진 支持端의 固定度.

Lateral bracing has long been used in design practice to enhance the carrying capacity of the lateral buckling of the beam. Many factors. critically important to lateral bracing performance. do not appear in design formulas. Some of these factors are discussed in this study for the application to short 1 - beams under repeated loadings through parametric studies with an analytical model : the brace 10' cation along the length of the beam. the height of the bracing above the shear center of the beam. and the strength and stiffness of the brace. The parametric studies are carried out using a propped cantilever arrangement. and also using a geometrically (fully) nonlinear beam model for the brace as well as the beam to capture the system buckling. An idealized bracing system is configured to restrain lateral motion. but not rotation. A multiaxial cyclic plasticity model is also implemented to better represent cyclic metal plasticity in con. junction with a consistent return mapping algorithm.

The reinforcement effect of buckling resistance steel damper on member with two-column and beam is evaluated by investigating the relationship of lateral load and displacement

The reinforcement effect of buckling resistance steel damper on member with two-column and beam is evaluated by investigating the relationship of lateral load and displacement.

The four buckling resistance steel dampers were tested under cyclic lateral load to investigate the relationship of lateral load and displacement. The main variables are the existence of cover plate for preventing from buckling of out-of-plane and thickness of sim plate with 3.2 mm, 4.5 mm and 7.0 mm. The test showed that steel damper with cover plate had the wider area of its hysteresis loop than that of without.

Recently, as the level of market competition in the structural engineering field continues to rise, structural designers are finding other ways to make their designs stand out. One way of doing that is to make the designs more economical without sacrificing efficiency. As a result, the use of stepped beams and the studies involving it has become more common. Stepped beams are beams that have a sudden increase in cross section along its length. The change in cross section is made by increasing the width and/or the thickness of the flanges along a certain length while maintaining the dimensions of the web. Most of the studies involving lateral torsional buckling of stepped beams are focused on developing equations and studying the effects of symmetry. However, the studies involving actual test experiments are still very limited. Thus, this study has three main objectives. The first objective of this study is to give a brief historical overview on the series of studies involving the lateral torsional buckling capacity of stepped beams and give an idea on its current state of the art. The second objective is to determine if the intuitive expectation that the lowest critical moment always corresponds to uniform bending moment holds true for stepped beams. The degree of symmetry is varied and several loading conditions are observed. The third objective of this study is to determine the actual inelastic lateral torsional buckling capacity of doubly stepped singly symmetric I-beams having compact and non-compact flange sections subjected to two point loading condition and to use the results obtained to determine the applicability of previously proposed equations in predicting the buckling strength of stepped beams. The results are obtained by conducting actual destructive tests on doubly stepped I-beams using a universal testing machine and running simulation tests using the finite element program, ABAQUS. The main factors that are considered for the experimental and finite element analysis are the degree of beam symmetry, the loading condition, the supports, the stepped beam factors and the unsupported length. The degree of symmetry of all the stepped beams analyzed is fixed at 0.7. The unsupported lengths of the beams analyzed are 3 meters and 4 meters. The results obtained from the analysis are compared with the results from design specifications to determine the effects of steps and from proposed design equations to determine the equations’ applicability and safety. Finally, the results revealed that the stepped beams did have an increase in lateral torsional buckling capacity in comparison with the prismatic beams and that the proposed equations are suitable to be used in predicting the strength of stepped beams having compact flanges under the observed loading condition. However, for beams having non-compact flanges, the previously proposed equations produced over conservative results. Further study can also be made on stepped beams with varying degree of symmetries, loading conditions, boundary conditions and stepped beam parameters.