폭두께비가 큰 각형CFT 단주의 설계식

김선희,최영환,최성모,Kim, Sun Hee,Choi, Young Whan,Choi, Sung Mo 한국강구조학회 2009 韓國鋼構造學會 論文集 Vol.21 No.5

The design standards, such as AISC-LRFD (2005) and KBC-2005, specify the maximum width-to-thickness ratio that can be used for computing the strength of the concrete-filled tube (CFT), and do not include any formula for computing the strength when the width-to-thickness ratio is over the limit. This paper proposes a strength equation for CFTs with a large width-to-thickness ratio by acknowledging the fact that the stiffened slender steel platehas substantial postbuckling strength, and that it therefore can be more economical to use it. The equation adopts the concept of effective width,which is very useful for plate analysis. By comparing the strengths of AISC2005, KBC2005, and the proposed method with the results of the experiment, where the width-to-thickness ratio was regarded as the main parameter, the applicability of the proposed method was verified. AISC(2005)나 KBC(2005)등의 기준에서는 콘크리트 충전 강관(Concrete Filled Steel Tube) 기둥의 내력산정에서 폭두께비의 제한을 두고 있으며 최대 폭두께비를 초과하는 기둥에 대해서는 설계식을 제시하지 않고 있다. 본 연구는 stiffened (양단지지) 플레이트에서는 좌굴이 발생하더라도 바로 내력저하가 발생하지 않고 상당한 양의 좌굴 후 강도를 발휘할 수 있어 폭두께비가 큰 강관을 사용하는 것이 경제적일 수 있다는 점을 착안, 유효폭 개념을 도입해서 폭두께비가 큰 각형 CFT의 강도를 계산할 수 있는 설계식을 제안하였다. AISC 2005, KBC 2005와 본 연구에서 제안한 식을, 폭두께비를 변수로 수행한 4개의 각형 CFT 기둥 실험결과와 비교하였며 제안된 설계식의 적용가능성을 확인하였다. 이에 Uy(2005), Dalin Liu(2005)는 폭두께비가 큰 단주 CFT에 한에서 선행 연구된 실험데이타를 근거로 제안 설계식을 단순적용 하였다. 폭두께비가 초과된 각형CFT 단주를 검토 대상기본으로 1. 용접 조립된 정사각형 단면 2. 모살용접된 정사각형 단면 (b/t 60mm. 80mm, 100mm) 3. 한 폭면의 폭두께비가 초과하는 직사각형단면의 (b/t 45.5) 실험체를 선정하여 제안식의 타당성을 검토해 보고자 한다.

고강도콘크리트 충전 각형강관기둥의 내력평가에 관한 연구

심종석,한덕전 한국구조물진단유지관리공학회 2011 한국구조물진단유지관리공학회 논문집 Vol.15 No.1

두께가 얇은 강관을 사용한 CFT기둥은 강관의 국부좌굴에 대한 구속효과로 내력상승을 기대할 수 있으므로 폭두께비가 작은 강관 CFT기둥에 비해 경제성을 확보할 수 있다. 본 논문의 목적은 각형 CFT기둥에 대한 기존 설계식의 타당성을 입증하고, 내력 증대에 따른 강관 폭두께비의 사용성 한계를 확인하고자 하였다. 실험의 주요변수로는 강관의 폭두께비, 콘크리트 각주의 높이 및 콘크리트 충전 유무로 하였다. 실험결과, 고강도 콘크리트를 충전한 박판의 각형강관기둥에서 충전콘크리트의 압축내력에 대한 강관의 구속효과가 크게 나타났으며, 비선형 해석에 따르면, 실험결과에 의한 내력은 전체 CFT단주 실험체에서해석값보다 다소 크게 나타남을 알 수 있었다. The CFT columns used in thin-walled steel tubes can be more economical, because it was expected the increase of strength by restriction for the local buckling of steel tubes. The purpose of this paper is to review feasibility of existing design formula and verify the applicability limit of width-to-thickness ratio for increasing the strength of rectangular CFT columns. As the main parameters of experiments, width-to-thickness ratios of steel tube, height of rectangular concrete columns, and concrete filled or not. The strength of concrete are selected to 90MPa. From the test results, the confinement effect of steel tube on the compressive strength of infilled concrete is remarkably appeared in the thin-walled rectangular steel tube columns infilled wih high strength concrete. By the non-linear analysis, the axial strength from experiment result was given higher than analysis result for all CFT stub columns.

충전성을 개선한 각형CFT구조의 기둥-보 접합부 구조적 거동

박제영(Park, Je-Young),이명재(Lee, Myung-Jae) 대한건축학회 2012 大韓建築學會論文集 : 構造系 Vol.28 No.11

Concrete-Filled Tube is a concrete-filled steel tube structure. Steel tube confines the concrete to increase the compressive strength, and the concrete contains the buckling of the tube. CFT structures require a diaphragm to prevent buckling of steel at connections. An outer diaphragm has better concrete filling than a through diaphragm due to a large bore, but being larger than the through diagram, it has poorer constructability and cooperation with building equipment. In this study, a rectangular CFT structure that uses different types of diaphragms in its upper and lower connections to improve the concrete filling was tested and analyzed via the FEM program. The building structure had a floor slab that was unified with the upper diaphragm, so the outer diaphragm was placed at the upper bound. Moreover, the through diaphragmwas placed at the lower connection to avoid obstruction frombuilding equipment. The CFT structure with the improved concrete filling showed the same structural behavior as the CFT structure with the use of the same type of diaphragms at the upper and lower connections.

충전성을 개선한 각형CFT구조의 기둥-보 접합부 구조적 거동

박제영,이명재 대한건축학회 2012 대한건축학회논문집 Vol.28 No.11

<P>&nbsp;&nbsp;Concrete-Filled Tube is a concrete-filled steel tube structure. Steel tube confines the concrete to increase the compressive strength, and the concrete contains the buckling of the tube. CFT structures require a diaphragm to prevent buckling of steel at connections. An outer diaphragm has better concrete filling than a through diaphragm due to a large bore, but being larger than the through diagram, it has poorer constructability and cooperation with building equipment. In this study, a rectangular CFT structure that uses different types of diaphragms in its upper and lower connections to improve the concrete filling was tested and analyzed via the FEM program. The building structure had a floor slab that was unified with the upper diaphragm, so the outer diaphragm was placed at the upper bound. Moreover, the through diaphragmwas placed at the lower connection to avoid obstruction frombuilding equipment. The CFT structure with the improved concrete filling showed the same structural behavior as the CFT structure with the use of the same type of diaphragms at the upper and lower connections.</P>

각형 CFT 단주의 하중-변형도 관계 모델

강현식,유영찬,문태섭,Kang, Hyun Sik,Yoo, Yeong Chan,Moon, Tae Sup 한국강구조학회 2000 韓國鋼構造學會 論文集 Vol.12 No.1

본 연구는 중심 압축을 받는 각형 CFT 단주의 하중-변형도 관계를 추정하기 위한 재료의 응력도-변형도 관계 모델화에 관한 것이다. 수정된 모델은 미일공동연구 결과식 형태를 기본으로 하여 본 연구자가 수행했던 실험결과로 수정된 것이다. 궁극적인 목적은 콘크리트와 강관의 강도 변화에 따른 거동 특성을 평가하기 위한 기초 자료의 제공에 있다. The model of load-strain relations for CFT stub columns subjected to centrally compressive axial load is shown in this paper. The modified model of concrete and steel is obtained by using the experimental data and the formulas of that is based on the foreign researcher's result. The purpose of this paper is to suggest the basic data for evaluating the behavior of CFT stub columns to be variable to the strength of concrete and steel.

세장 단면의 고강도 강관을 적용한 각형 CFT 기둥의 압축실험

이호준,박홍근,최인락,Lee, Ho Jun,Park, Hong Gun,Choi, In Rak 한국강구조학회 2015 韓國鋼構造學會 論文集 Vol.27 No.2

각형 CFT 기둥에 대한 실험 연구를 수행하였다. 본 연구는 세장 단면의 고강도 강관을 적용한 CFT 기둥의 압축성능 평가하는 것이 주요 목적이다. 실험 변수는 강관의 판폭두께비, 콘크리트 강도, 강관 항복강도, 그리고 스티프너의 사용여부이다. 총 5개의 기둥 실험체에 대하여 중심압축 실험을 수행하였다. 고강도 강관을 적용한 실험체는 탄성국부좌굴이 발생하였지만, 높은 항복강도로 인하여 상당한 후좌굴강도를 발휘하였다. 또한, 실험결과는 현행 설계기준에 의한 예상강도를 대체로 만족하였다. 세장 단면의 고강도 강관에 스티프너를 보강할 경우 강도와 변형능력 면에서 우수한 구조성능을 발휘하였다. An experimental study was performed for thin-walled rectangular concrete-filled tubular (CFT) columns. The present study mainly focused on evaluation of the axial load-carrying capacity of concrete-filled tubular columns using high-strength steel and slender section. The test parameters were width-to-thickness ratio, concrete strength, steel yield strength, and the use of stiffeners. Five specimens were tested under monotonic axial loading. Although elastic local buckling occurred in the slender-section specimens with high-strength steel, the specimens exhibited considerable post-buckling reserve. The test results also satisfied the predictions of a current design code. The specimens strengthened with vertical stiffeners exhibited improved strength and ductility when compared with the un-stiffened specimens.

무내화피복 각형 CFT 기둥의 50층 규모 건물적용에 관한 사례 연구

심천수(Shim Chun-Soo),박수희(Park Su-Hee),최인학(Choi In-Hak),김용구(Kim Yong-Gu),최성모(Choi Sung-Mo) 대한건축학회 2007 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.27 No.1

This study introduces a building application considering fire resistances in all countries of the world and proposes application requirements and methods of the performance design in Korea through the construction examples of structures designed considering the fire resistance. In U.S.A and Japan, many studies about the fire resistance of concrete filled tube column and the structural design considering fire resistance have been progressed and, the performance design about members is standardized. In Korea, the structural design isn't considered to the performance of the members and the fire resistances of three times is only related to thickness of the protected materials. The purpose of this study is to be recognized on requirements of performance design considering fire resistance through investigation for the present condition and to propose the application methods of the performance design considering fire resistance for concrete filled tube columns in Korea.

각형 CFT 기둥-보 수평 내다이아프램 접합부의 구조성능에 관한 해석

정원제(Jung Won-Je),이성휘(Lee Seong-Hui),오헌근(Oh Hun-Keun),김영호(Kim Young-Ho),최성모(Choi, Sung-Mo) 대한건축학회 2010 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.30 No.1(구조계)

각형 콘크리트 충전강관기둥의 단면형태별 축압축강도 설계식 분석

홍건호(Hong, Geon-Ho),최인락(Choi, In-Rak),정경수(Chung, Kyung-Soo) 대한건축학회 2014 大韓建築學會論文集 : 構造系 Vol.30 No.11

The purpose of this study is to analyze the axial load capacity equations for rectangular CFT columns in the AISC 360-10(the US design code for structural steel buildings) which is being investigated as a revision of Korean Building Code. Main parameters were the width-to-thickness ratios of composite member and material strength as 30∼100MPa of concrete compressive strength and 325∼725MPa of yield strength of structural steel. The first method of changing width-to-thickness ratios was to fix the thickness of structural steel to 5mm and to increase the size of member. The second method was to fix the size of member to 620mm×620mm and to change the thickness of structural steel. The analysis results indicated that axial load capacity used higher strength steel is lower than the capacity used lower strength one in some regions although the section size was equal. The reason of this result is due to the different section type that is classified by the equation of limit width-to-thickness ratios. When the yield strength of structural steel become higher, its section type and axial load capacity equation is changed though its width-to-thickness ratio is the same with the lower yield strength members. The region of this phenomenon is become wider following to the increase of concrete compressive strength because part of concrete load capacity is govern the total load capacity of members. To resolve this irregular phenomenon that axial load capacity is reversed in some region, it is necessary to modify the code provision for calculation the load capacity in high strength materials.

링다이아프램 보강 용접조립각형 CFT 기둥-보 접합부의 성능 평가

김도범,윤여상,염경수,최성모 한국복합신소재구조학회 2018 복합신소재구조학회논문집 Vol.9 No.3

ACT Column은 기존 CFT 기둥보다 얇은 강판으로도 동일한 구조적 성능을 발휘할 수 있으며, 콘크리트의 구속효과와 강관의 항복 후 좌굴응력의 향상을 기대할 수 있다. ACT Column은 보-기둥 접합부에 외다이아프램을 사용한 접합상세가 적용된다. 그러나 ACT Column 외부에 콘크리트가 피복되는 SRC 타입에서는 외다이아프램을 사용한 접합부의 적용이 난해하다. 그래서 ACT Column의 외부에 수직 스티프너와 수평 스티프너를 사용한 접합상세를 제안하였다. 본 논문에서는 제안상세를 대상으로 단순인장실험을 통해 성능검증을 수행하였다. 실험체는 현장에 사용량이 많은 크기의 ACT Column 으로 2개의 실험체를 제작하였다. 보 플랜지와 보 플랜지의 양측부에 부착된 윙플레이트를 통해 보 플랜지의 단면 내력이 링다이아프램으로 전달되는 명확한 응력전달매커니즘을 나타내었으며, 보 플랜지 전단면이 소성화되어 파괴되었다. 윙플레이트의 크기가 클수록 하중전달량이 증가하였으며, 제안한 접합상세의 강도평가식을 제시하였다. The ACT Column can exhibit the same structural performance even with thinner steel plates than existing CFT columns. And we can expect to improve the confinement effect of concrete, and buckling stress. The beam to column connection was applied using the external diaphragm at the ACT column. However, in the SRC type where concrete is covered on the outside of the ACT column, it is difficult to apply the connection using external diaphragm. So, we proposed the connection detail using vertical stiffeners and horizontal stiffeners on the outside of the ACT column. And in this paper, the performance of the proposed detail is verified by simple tensile test. Two specimens of use a lot on the site were produced. The test results, a clear stress transfer mechanism of the suggested detail is shown in which the cross-sectional strength of the beam flange is transmitted to the ring diaphragm through the wing plate attached to both sides of the beam flange. Then, the fracture occurred as the beam flange’s all sections became plasticized. Also, the results show that the larger the wing plate size, the greater the load transfer. And the strength evaluation formula of the proposed connection detail is presented.