• 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.

• 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.

• 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.

• 한국지진공학회논문집
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• 제15권1호
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• pp.49-56
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• 2011

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.

• 국제초고층학회논문집
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• 제3권1호
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• pp.81-87
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• 2014

The use of Buckling Restrained Braces (BRB) for enhancing the performance of the buildings is gaining wider acceptance. This paper presents the first application of these devices in a major high-rise building in the Philippines. A 50-storey residential reinforced concrete building tower, with ductile core wall, with BRB system is investigated. The detailed modeling and design procedure of buckling restrained brace system is presented for the optimal design against the two distinct levels of earthquake ground motions; serviceable behavior for frequent earthquakes and very low probability of collapse under extremely rare earthquakes. The stiffness and strength of the buckling restrained brace system are adjusted to optimize the performance of the structural system under different levels of earthquakes. Response spectrum analysis is conducted for Design Basis Earthquake level and Service level, while nonlinear time history analysis is performed for the most credible earthquake. The case study results show the effectiveness of buckling restrained braces.

• Earthquakes and Structures
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• 제16권5호
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• pp.589-599
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• 2019

Conventional buckling restrained braces used in concentrically braced frames are expected to yield in both tension and compression without major degradation of capacity under severe seismic ground motions. One of the weakness points of a standard buckling restrained braced frame is the low post-yield stiffness and thus large residual deformation under moderate to severe ground motions. This phenomenon can be attributed to low post-yield stiffness of core member in a BRB. This paper introduces a multi-core buckling restrained brace. The multi-core term arises from the use of more than one core component with different steel materials, including high-performance steel (HPS-70W) and stainless steel (304L) with high strain hardening properties. Nonlinear dynamic time history analyses were conducted on variety of diagonally braced frames with different heights, in order to compare the seismic performance of regular and multi-core buckling restrained braced frames. The results exhibited that the proposed multi-core buckling restrained braces reduce inter-story and especially residual drift demands in BRBFs. In addition, the results of seismic fragility analysis designated that the probability of exceedance of residual drifts in multi-core buckling restrained braced frames is significantly lower in comparison to standard BRBFs.

• 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.

• 한국공간구조학회논문집
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• 제14권3호
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• pp.57-65
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• 2014

In order to improve the wind performance of buckling-restrained braces (BRBs), Hybrid buckling-restrained braces (H-BRBs) have been studied in Korea. The seismic performance of H-BRBs is different according to the action of VE damper. In this study, the nonlinear time history analyses have been performed on the parameters such as brace types and input earthquakes. The results of the study suggest that H-BRBs meet the BRB's requirement of ANSI/AISC 341-10 only if VE damper is not working during an earthquake.