• 대한건축학회논문집:구조계
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• 제35권7호
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• pp.139-146
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• 2019

This study examined the effect of various arrangement methods for forming peripheral closed hoops in the jacket section on the axial behavior of section enlargement strengthening columns. Four types of peripheral closed hoops arranged in the jacket section were prepared as follows: 1) Closed connection of prefabricated bar units (column P); 2) V-clip installation across the overlapped legs of channel-type bars (column V); 3) Use of glass fiber mesh for an alternative of steel bars (column F); and 4) combination of prefabricated bar units and glass fiber mesh (column PF). The V-clip is designed to form the closed hoops in the jacket section using the overlapped channel-type bars, preventing the opening of the channel bar legs. The glass fiber mesh is to examine the feasibility to apply for closed hoops in the jacket section as an alternative for steel bars, considering the easy construction. In the jacket section of all the strengthened columns, V-ties were arranged for supplementary ties, avoiding the interruption of the existing column. The axial stiffness and strength of the strengthened columns were insignificantly affected by the arrangement methods of closed hoops in the jacket section. The axial ductility ratio of the strengthened columns P, V, and PF was enhanced more than twice of that measured in the non-seismic existing column. However, the column F exhibited a lower ductility than the other strengthened columns because of the fracture of the mesh at the ultimate strength of the column. The V-clip approach was favorable to enhance the ductility of the strengthened column, preventing the opening of the legs of channel-type bars.

• Steel and Composite Structures
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• 제37권1호
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• pp.15-26
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• 2020

The top-and-seat angles with double web angles are commonly used in the design of beam-to-column joints in Asian and North American countries. The seismic behavior analysis of these joints with large cross-section size of beam and column (often connected by four or more bolts) is a challenge due to the effects from the relatively larger size of stiffened angles and the composite action from the adjacent concrete slab. This paper presents an experimental investigation on the seismic performance of exterior composite beam-to-column joints with stiffened angles under cyclic loading. Four full-scale composite joints with different configuration (only one specimen contain top angle in concrete slab) were designed and tested. The joint specimens were designed by considering the effects of top angles, longitudinal reinforcement bars and arrangement of bolts. The behavior of the joints was carefully investigated, in terms of the failure modes, slippage, backbone curves, strength degradation, and energy dissipation abilities. It was found that the slippage between top-and-seat angles and beam flange, web angle and beam web led to a notable pinching effect, in addition, the ability of the energy dissipation was significantly reduced. The effect of anchored beams on the behavior of the joints was limited due to premature failure in concrete, the concrete slab that closes to the column flange and upper flange of beam plays an significant role when the joint subjected to the sagging moment. It is demonstrated that the ductility of the joints was significantly improved by the staggered bolts and welded longitudinal reinforcement bars.

• Steel and Composite Structures
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• 제28권3호
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• pp.309-318
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• 2018

Buckling Restrained Braced (BRB) frames have been widely used as an efficient seismic load resisting system in recent years mostly due to their symmetric and stable hysteretic behavior and significant energy dissipation capacity. In this study, to provide a better understanding of the behavior of BRB frames with various beam-column connections, a numerical study using non-linear finite element (FE) analysis is conducted. All models are implemented in the Abaqus software package following an explicit formulation. Initially, the results of the FE model are verified with experimental data. Then, diverse beam-column connections are modeled for the sake of comparison from the shear capacity, energy dissipation and frame hysteresis behavior points of view until appropriate performance is assessed. The considered connections are divided into three different categories: (1) simple beam-column connections including connection by web angle and connection by seat angle; (2) semi-rigid connection including connection by web and seat angles; and (3) rigid beam-column connections by upper-lower beam plates and beam connections with web and flange splices. Results of the non-linear FE analyses show that these types of beam-column connections have little effect on the maximum story drift and shear capacity of BRB frames. However, the connection type has a significant effect on the amount of energy dissipation and hysteresis behavior of BRB frames. Also, changes in length and thickness of the angles in simple and semi-rigid connections and changes in length and thickness of plates in rigid connections have slight effects (less than 4%) on the overall frame behavior.

• 한국구조물진단유지관리공학회 논문집
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• 제10권6호
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• pp.197-204
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• 2006

최근 시공의 합리화와 경제성의 목적으로 한 다양한 연구가 진행되고 있다. 철근 콘크리트 기둥과 철골 보로 이루어진 RCS 구조의 개발에 대한 연구 역시 활발해지고 있다. RCS 구조 보-기둥 접합부 패널존의 저항기구는 내부패널에서 외부패널로 응력이 전달될 때 직교보의 영향을 받지만, 기존연구에는 직교보의 영향을 고려하지 않고 있다. 본 연구에서는 웨브, 플랜지, 직교보의 두께, FBP의 유뮤등 다양한 변수들을 가지는 5개의 철근콘크리트 기둥과 철골보로 이루어진 보-기둥 내부접합부 실험체의 실험을 통해 직교보들의 영향과 구조적 성능을 조사하고자 한다. 이러한 실험결과들로부터, 보-기둥 접합부의 직교보가 전단내력과 구조성능을 향상시키는데 효과적이라는 것을 알 수 있다.

• 대한기계학회논문집 C: 기술과 교육
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• 제3권4호
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• pp.307-312
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• 2015

탑승교는 여객터미널청사에서 항공기 출입구 사이를 이어주는 이동통로를 탑승객에게 제공하는 공항 편의시설 중 하나다. 본 연구에서는 유한요소 해석법을 이용하여 탑승교 설계시 리프트 컬럼의 배치설계가 탑승교 구조물의 처짐 및 응력상태에 미치는 영향 비교 검토하였다. 그 결과 탑승교 터널 프레임의 중첩구간에서 최대응력이 발생함을 확인하였고, 리프트 컬럼 배치설계와 그 값의 크기가 매우 밀접한 관계를 갖고 있음을 확인하였다.

• Structural Engineering and Mechanics
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• 제73권2호
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• pp.167-179
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• 2020

This study provides a simplified method for the evaluation of shear lag stress in rectangular box T-joints. The occurrence of shear lag phenomenon in the box T-joint generates stress concentration localized at both web-flange junctions of the beam, which leads to cracking or failure in the weld region of the joint. To prevent such critical circumstance, peak stress at the weld region is required to be checked during a preliminary design stage. In this paper, the shear lag stresses in the T-joints were evaluated using least-work solution in which the longitudinal displacements of the beam flange and web were presumed. The evaluation process considered particularly the effect of column flange flexibility, which was represented by an axial spring model, on the shear lag stress distribution. A simplified method for stress evaluation was provided to avoid solving complex mathematical problems using a stress modification factor β_s from a parametric study. The results showed that the proposed method was valid for predicting the shear lag stress in the box T-joints manually, as well compared with finite element results. The results are further summarized, discussed, and clarified that more flexible column flange caused higher stress concentration.

• Steel and Composite Structures
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• 제28권4호
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• pp.471-482
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• 2018

The composite reinforced concrete and steel (RCS) structural systems have larger structural lateral stiffness, higher inherent structural damping, and faster construction speed than either traditional reinforcement concrete or steel structures. In this paper, four RCS subassemblies with or without the RC slab designed following a strong column-weak beam philosophy were constructed and tested under reversed-cyclic loading. Parameters including the width of slab and composite effect of the RC slab and beam were explored. The test results showed that all specimens performed in a ductile manner with plastic hinges formed in the beam ends near the column faces. The seismic responses of composite connections are influenced significantly by different width of slabs. Compared with that of the steel beam without the RC slab, it was found that the load carrying capacity of composite connections with the RC slab increased by 30% on average, and strength degradation, energy dissipation also had better performance, while the ductility of that were almost the same. Furthermore, the contribution of connection deformation to the overall specimen displacement was analyzed and compared. It decreased approximately 10% due to the coupling effect in the columns and beams with the RC slab. Based on the test result, some suggestions are presented for the design of composite RCS joints.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2009년도 춘계 학술대회 제21권1호
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• pp.493-494
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• 2009

와이어로프 유닛으로 보강된 철근콘크리트 기둥의 T형 강판 정착효과를 알아보기 위해 중심축하중과 횡하중을 동시에 받는 3개의 기둥 시험체가 휨 실험되었다. 주요변수는 T형 강판의 정착 유무이다. 실험된 기둥의 연성비는 기존 연구자들의 띠철근의 실험결과와 비교되었다. 실험결과 T형 강판의 정착으로 횡하중 내력 및 연성비는 각각 무보강 기둥에 비해 40%와 130% 향상되었다. 특히, 동일한 유효횡보강지수에서 T형 강판이 정착된 보강기둥의 연성비는 띠철근 기둥에 비해 현저히 높았다.

• 한국가스학회:학술대회논문집
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• 한국가스학회 2005년도 추계학술발표회 논문집
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• pp.141-145
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• 2005

DME (Di-Methyl Ether) is a new clean fuel and an environmental-friendly energy resource, also is recently increasing with an alternative interest because of the industrial use. DME has been shown to have excellent properties as a diesel fuel giving emission level better than ULEV standard. So it has been attracting considerable as an alternative diesel fuel. In this study, we carried out simulation of separation and purification process of demo plant for 101on per day DME production, which cause the effect that is important in productivity, from operation results of pilot plant for 50kg per day DME production. The liquefied stream, which was separated by gas-liquid separator after DME reactor, includes $CO_2$, DME, Methanol and $H_2O$. We established three distillation columns for separation and purification of the stream. $CO_2$ was extracted from the stream by first distillation column, DME was extracted by second column and Methanol was extracted by third column. We investigated and analyzed the effect which the actual operation variables cause in efficiency of process and optimized process, finally we got the DME of purity $100\%$.

• 교육시설 논문지
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• 제21권2호
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• pp.33-39
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• 2014

In the case of low-rise buildings in seismic performance evaluation, lateral force resistance of the pillars affects the seismic performance of the building. Evaluation of the seismic performance of the column is determined by the holding performance is evaluated by comparing the shear strength and bending strength it was destroyed bylow intensity. In case of the school building, in order to install the large windows for ventilation and lighting of the partition walls are located between the pillars. The case of the pillars of these, shear failure occurs in the event of an earthquake is often, in the seismic performance evaluation, partition wall and the wall of the shim is evaluated ignoring, pillar of the general pillars If you have to calculate the results of the seismic performance distorted that are destroyed by bending behavior can be evaluated as often. Results of the study, when assessed by distinguishing the effective length of the column, it was found that when a seismic load is applied, it is possible to accurately predict the failure mode, reliable results of seismic performance evaluation of the school building.