• Structural Engineering and Mechanics
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• 제70권5호
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• pp.591-600
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• 2019

Steel tubular buckling controlled braces are well known as being simple, practical and cost-effective lateral force resisting systems. Although these system features have gained the attention of the researchers over the last decade, steel tubular buckling controlled braces currently have limited application. Indeed, only a few steel tubes tightly encased within each other exist in the steel industry. In this paper, a new and practical design method is proposed in order to better promote the widespeared application for current steel tubular buckling controlled brace applications. In order to reach this goal, a holed-adapter made with polyoxymethylene adaptable to all round and square steel sections, was developed to use as infiller. The research program presents designing, producing and displacement controlled cyclic loading tests of a conventional tubular brace and a buckling controlled composite brace. In addition, numerical analysis was carried out to compare the experimental results. As a result of the experimental studies, buckling was controlled up to 0.88 % drift ratio and the energy dissipation capacity of the conventional tubular brace increased 1.46 times due to the proposed design. The main conclusion of this research is that polyoxymethylene is a highly suitable material for the production of steel tubular buckling controlled braces.

• Steel and Composite Structures
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• 제47권1호
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• pp.135-145
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• 2023

This study presents a numerical investigation into the hysteretic behavior of cold-formed austenitic stainless steel square hollow section (SHS) brace members using a commercial finite element (FE) analysis software ABAQUS/Standard. The initial/post buckling and fracture life of SHS brace members are comprehensively investigated through parametric studies with FE models incorporating ductile fracture model, which is validated against the existing laboratory test results collected from the literature. It is found that the current predictive models are applicable for the initial buckling strengths of SHS brace members under cyclic loading, while result in significant inaccuracy in predictions for the post-buckling strength and fracture life. The modified predictive model is therefore proposed and the applicability was then confirmed through excellent comparisons with test results for cold-formed austenitic stainless SHS brace members.

• Steel and Composite Structures
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• 제23권2호
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• pp.217-228
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• 2017

Braces are one of the retrofitting systems of structure under earthquake loading. Buckling restrained braces (BRBs) are one of the very efficient braces for lateral loads. One of the key needs for a desirable and acceptable behavior of buckling-restraining brace members under intensive loading is that it prevents total buckling until the bracing member tolerates enough plastic deformation and ductility. This paper presents the results of a set of analysis by finite element method on buckling restrained braces in which the filler materials within the restraining member have been removed. These braces contain core as the conventional BRBs, but they have a different buckling restrained system. The purpose of this analysis is conducting a parametric study on various empty spaces between core and restraining member, the effect of friction between core and restraining member and applying initial deformation to brace system to investigate the global buckling behavior of these braces. The results of analysis indicate that the flexural stiffness of restraining member, regardless of the amount of empty space, can influence the global buckling behavior of brace significantly.

• Structural Engineering and Mechanics
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• 제84권2호
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• pp.269-283
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• 2022

In this paper, a particular type of all-steel HSS brace members with a locally reduced cross-sectional area was experimentally and numerically investigated. The brace member was strengthened against local buckling with inner and outer boxes in the reduced area. Four single-span braced frames were tested under cyclic lateral loadings. Specimens included a simple steel frame with a conventional box-shaped brace and three other all-steel reduced section buckling-restrained braces. After conducting the experimental program, numerical models of the proposed brace were developed and verified with experimental results. Then the length of the proposed fuse was increased and its effect on the cyclic behavior of the brace was investigated numerically. Eventually, the brace was detailed with a fuse-to-brace length of 30%, as well as the cross-sectional area of the fuse-to-brace of 30%, and the cyclic behavior of the system was studied numerically. The study showed that the proposed brace is stable up to a 2% drift ratio, and the plastic cumulative deformation requirement of AISC (2016) is easily achieved. The proposed brace has sufficient ductility and stability and is lighter, as well as easier to be fabricated, compared to the conventional mortar-filled BRB and all-steel BRB.

• 한국구조물진단유지관리공학회 논문집
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• 제11권5호
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• pp.181-188
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• 2007

본 연구에서는 원형강관 가새의 국부좌굴에 의한 내력감소를 배제하기 위하여, 가새의 국부좌굴 거동을 파악하고 좌굴제어 방법을 찾고자 한다. 좌굴을 제어하기 위한 방법으로, 하나는 좌굴 영역에 커버플레이트를 설치하여 좌굴을 구속함으로써 변형능력을 확보하고자 하는 것이며, 다른 하나는 가새 중앙부에 강봉과 스프링을 이용한 수축장치를 삽입하여 압축 시 좌굴의 위험을 배제하는 것이다. 본 연구의 목적은 국부좌굴을 구속하거나 배제하기 위한 좌굴제어시스템을 제안하고, 실험을 통하여 제안한 방법의 적용성을 조사, 검토하는 것이다. 또한 좌굴제어에 따른 성능향상을 정량적으로 평가하는 것이다.

• 한국구조물진단유지관리공학회 논문집
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• 제20권1호
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• pp.72-84
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• 2016

종래 브레이스시스템은 횡력저항 및 층변위제어에 효율적이며 골조물량 감소에 따른 경제성이 향상되어 일반적인 강구조 횡력저항시스템으로 적용되고 있다. 그러나 압축측에서 항복응력에 도달하기 전 가새의 좌굴이 발생하여 충분한 내력을 발휘하지 못하고, 내력열화형의 이력거동으로 불안정상태가 된다. 좌굴에 의한 내력저하 개선시스템으로 중심재를 구속하여 좌굴방지가 가능한 비좌굴가새는 심재의 항복 이후에도 안정적인 이력특성을 나타내어 종래 브레이스에 비하여 에너지흡수능력이 우수하다. 최근 10년간 미국, 일본 및 대만에서 매우 다양한 형상의 비좌굴가새가 제안되었으나, 기존의 실험연구에서는 그 형상이 매우 제한적인 경향을 보이고 있다. 본 연구에서는 조립형 Precast RC 보강재를 가지는 비좌굴가새를 제작하고 이력특성을 평가하기 위한 부재실험을 수행하였다. 또한 실험결과를 AISC(2005)의 요구조항과 비교하였다.

• 한국공간구조학회논문집
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• 제20권3호
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• pp.43-52
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• 2020

In this study, the Buckling restrained braces reinforced with engineering plastics that can compensate for the disadvantages in the manufacturing process of the existing buckling restrained brace. The proposed PC-BRB was fabricated to evaluate the reinforcement effect by carrying out a structural performance test and a full-scale two-layer frame test through cyclic loading test. As a result of PC-BRB's incremental and cyclic loading test, stable hysteresis behavior was achieved within the target displacement, and the compressive strength adjustment coefficient satisfied the recommendation. As a result of the real frame experiment, the strength of the reinforced specimen increased compared to the unreinforced specimen, and the ductility and energy dissipation increased.

• Earthquakes and Structures
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• 제7권4호
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• pp.553-570
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• 2014

In this study, nonlinear dynamic analyses were performed in order to evaluate and compare the structural response of different type of moment resisting frame buildings equipped with conventional braces (CBs) and buckling restrained braces (BRBs) subjected to near-field ground motions. For this, the case study frames, namely, ordinary moment-resisting frame (OMRF) and special moment-resisting frame (SMRF) having two equal bays of 6 m and a total height of 20 m were utilized. Then, CBs and BRBs were inserted in the bays of the existing frames. As a brace pattern, diagonal type with different configurations were used for the braced frame structures. For the earthquake excitation, artificial pulses equivalent to Northridge and Kobe earthquake records were taken into account. The results in terms of the inter-story drift index, global damage index, base shear, top shear, damage index, and plastification were discussed. The analysis of the results indicated a considerable improvement in the structural performance of the existing frames with the inclusion of conventional and especially buckling-restrained braces.

• 한국공간구조학회논문집
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• 제21권2호
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• pp.81-88
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• 2021

In this paper, nonlinear finite element analysis was conducted based on the experimental results on buckling restrained brace. The reliability of the analytical model was verified by comparing the results of experimental studies with hysteresis loop, bi-linear curve, cumulative energy dissipation capacity, and equivalent viscous damping. A valid finite element model has been secured and will be used as basic data for finite element analysis of buckling restrained braces in the future.

• 한국공간구조학회논문집
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• 제22권1호
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• pp.51-57
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• 2022

In this paper, based on the finite element analysis model verified in previous studies, a new model of a buckling restrained brace reinforced with a steel plate was proposed. A design formula was proposed for the new model to dissipate energy without buckling the steel core under load protocol, and the performance of the model satisfying the design formula was evaluated by comparing it with the previous model through the results of hysteresis loop, bi-linear curve, cumulative energy dissipation capacity, and equivalent viscous damping.