KIOST – 한국해양과학기술원
– Korea Institute of Ocean Science & Technology
– Since 1973
KIOST는 혁신적이고 선도적인 해양 연구개발을 통해 해양기반기술과 응용과학기술을 통해 해양국가 번영의 꿈을 실현하는데 큰 역할을 할 것입니다.
AutoDSCT
– AutoDSCT
Automatic Designer for DSCT Columns & Wind Towers
– User Inputs
목표 용량 : 축 하중, 휨 모멘트
외부 튜브 직경
재료 특성
– Result / Post-processing
10가지 다른 크기 조합에 대한 비교 결과
– Process
좌굴 기준을 충족하는 외부 튜브 두께 결정
10개의 서로 다른 중공비율을 정의하고, 최적화된 내부 튜브 두께를 얻음
10가지 조합에 대한 전체 분석 결과를 제공하여 설계 개선
화면 구성
프로그램은 Pre / Solver / Post processor 로 크게 구분됩니다.
Task pane 을 통해서 전체 가능한 작업을 파악할 수 있습니다.
Menu 에 있는 항목들을 작업 절차에 맞춰 Task pane 에 Pre / Solver / Post Processor 에 맞추어 작업을 분리하였습니다.
Task pane 에서 작업을 선택하면 선택된 작업에 맞춰 입력 및 결과 확인 창이 활성화 됩니다.
Pre Processor 과정
Pre Process 는 DSCT Tower 해석에 필요한 정보를 입력합니다.
Auto DSCT 를 클릭하여 입력을 활성화합니다.
각각의 변수를 입력하거나 수정하고 Apply 버튼을 누르면 Auto DSCT 해석에 대한 설정이 완료됩니다.
Apply 를 눌러서 변수 변경을 반영하지 않고 다른 작업으로 이동하면 입력한 값들은 사라집니다.
그리고 사용자가 입력한 Input 값은 Solver progress > View Input file 에서 사용자가 입력한 값을 확인할 수 있다.
아래의 그림은 사용자가 입력한 Input 파일입니다.
이렇게 설정한 입력값을 파일로 저장할 수 있습니다.
저장된 파일은 다시 읽어오도록 되어있습니다.
파일을 저장하고 읽어오는 방법은 Windows 에서의 방식과 동일하므로 설명은 생략하겠습니다.
Solver Processor 과정
Solver 를 구동하기 전에 반드시 변경된 변수에 대한 저장이 필요합니다. 저장되지 않은 상태에서 “Run Solver” 를 클릭하면 파일을 저장되지 않았다는 메시지와 저장할지를 묻는 메시지 창이 화면에 표시됩니다.
다음 과정으로 입력이 완료되면 Solver 를 구동합니다.
“Rus Solver” 를 클릭하면 Solver manager 가 구동되면서 Solving 진행사항을 알려줍니다.
또한 Solver 를 정지하는 기능을 제공합니다. “Stop” 버튼을 클릭하여 현재 진행중인 Solver 를 중지할 수 있습니다. 구동 중에 중단하고 다시 실행하면 Solver 가 처음부터 다시 구동되므로 중지 시 주의가 필요합니다. 아래 그림은 Solver 가 진행 중에 메시지를 출력하는 화면을 보여줍니다. Progress 창을 통해서 현재 진행중인 상태를 보여주고 Stop을 눌러서 진행중인 solver를 중단하는 기능을 제공합니다.
Solver 가 정상적으로 완료되면 메시지를 출력하는 정보 창이 사라지고 아래와 같이 Solver 의 결과를 요약한 화면이 표시됩니다. 이 결과는 전체적인 Design parameter 을 총괄한 Table 정보와 Chart 정보를 화면에 표시합니다.
Post Processor 과정
Solve 의 해석결과는 Recommend Design case 에 대해서 Tree 창에 표시하고 Recommend Design case 를 종합하여 Design case 를 제시합니다.
Recommend Design 은 input 변수에 따라 1개에서 최대 10개까지 보여집니다.
각각의 Recommend Design 을 클릭하면 case 별로 결과를 화면에 표시해줍니다.
Solver 의 Output 파일에 출력된 데이터를 정리하여 Table 과 Chart 형태로 결과가 도시됩니다.
그리고 Chart 를 구성하는 Raw 데이터 항목들을 확인하기 위해서 Recommended Design 의 하위단계를 클릭합니다.
그럼 다음과 같이 raw 데이터가 Table 으로 표시되는것을 확인할 수 있습니다.
Table 창 위에서 오른쪽 마우스를 클릭하면 아래와 같은 팝업 메뉴가 나타나고 Table 데이터를 엑셀로 출력할 수 있습니다.
Chart 창을 클릭하고 차트 위에서 오른쪽 마우스를 클릭하면 다음과 같은 popup 이 화면에 표시됩니다.
Serch 는 데이터를 검색하기 위한 기능으로 마우스로 Curve 를 클릭하면 클릭한 점의 X, Y 좌표 값을 화면에 표시한다.
Move 는 Chart 를 X, Y 축으로 이동하는 기능을 제공한다.
Zoom 은 마우스로 사각형 영역을 선택하면 선택한 영역으로 화면에 데이터가 표시된다.
Zoom Out 은 현재 차트가 Zoom in 되어있는 경우 Zoom out 되어 영역이 더 많은 데이터를 화면에 보여준다.
Reset 은 초기화면의 데이터가 보여지도록 영역이 다시 설정된다.
Export Excel 은 현재 차트의 데이터를 엑셀로 출력하는 기능을 제공한다.
Copy to Clipboard 는 현재 선택된 Chart 를 bitmap 이미지로 변환하여 Windows 의 clipboard 메모리로 복사한다.
Chart 의 X, Y Label 의 표시된 영역을 두 번 클릭하면 데이터의 X, Y range 영역을 설정할 수 있는 dialog 창이 화면에 표시됩니다.
Auto Range 는 프로그램이 계산하여 X, Y Range 의 Min, Max 를 계산하고
Set Range 는 사용자가 Min, Max 를 설정한다.
Set Range 를 선택하면 X, Y 의 Min, Max 를 입력하는 창이 활성화된다.
Label 에서 X, Y Chart 의 Title 을 변경할 수 있다.
해석 결과 중 요약된 결과를 보기 위해서는 Post Processor 창에서 Design case 를 클릭합니다.
아래 그림은 Result 를 클릭했을 때 화면에 출력되는 Result 요약 화면입니다.
또한 Solver 에서 산출된 해석 결과 파일을 직접적으로 확인하는 기능도 제공합니다.
아래 그림은 Solver 해석 결과 파일을 가공하지 않고 Text 로 보여줍니다.
이론 관련
Behavior of a hollow RC column with an internal tube.pdf
A non-linear column model of an internally confined hollow (ICH) reinforced concrete (RC) column was suggested and column tests were performed. The suggested column model considered the confining effect and the material non-linearity of the concrete. To verify the suggested column model and to investigate the behaviour of an ICH RC column, quasi-static tests were performed for three different ICH RC columns and a solid RC column. The analysis results by the suggested model were agreeable with the test results, and they showed that it was reasonable to consider the confining effect of concrete. The test results showed that an ICH RC column has high strength, high energy-absorbing capacity, a normal damage index and acceptable ductility, which can be controlled by the thickness and the type of its internal tube.
Compressive Strength of Circular Hollow Reinforced Concrete Confined by an Internal Steel Tube.pdf
When concrete is confined, its strength is enhanced by confining stress. Therefore many researchers have studied the confinement and its effect in a reinforced concrete (RC) member. However, their research has focused on making confining pressure from the outside of the member. In a hollow RC member, it is impossible to confine its concrete triaxially because it has a hollow section. The concrete in a hollow RC member is usually in the state of biaxially confinement, and it shows lower strength than the concrete in a solid RC member, which is confined triaxially. In this study, the compressive strength of the concrete in a hollow RC column with an internal steel tube was investigated. The internal tube makes the concrete confined triaxially with internal confinement. To show the existence and the effect of the internal confinement, an experiment was performed. Fourteen specimens were tested. The test results showed that the internal confinement existed and made the concrete in the state of triaxial confinement.
JCMB2121.pdf
The use of concrete filled steel tube (CFT) columns is growing because of their superior performance. However, in some applications, CFT columns might be uneconomical or massive because they should be fully filled with concrete. To overcome these disadvantages, double-skinned composite tubular (DSCT) columns were suggested and have been studied by many researchers. In this study, a nonlinear concrete model was suggested for the analysis of DSCT columns. The model was developed by modifying Manderet al.’s unified concrete model. The stress–strain model of the concrete in a DSCT column was defined by identifying the possible failure modes of the column and deriving the equations for the confining pressure for each failure mode from equilibriums. By using derived equations, a computer program was coded and parametric studies were performed for some examples. The analysis results were verified by comparisons with the experimental results from other researchers. The proposed nonlinear concrete model explains why a DSCT column has enhanced strength beyond the sum of the strengths of its component parts which are an inner tube, an outer tube, and unconfined concrete.
Magazine of Concrete Research200808.pdf
A hollow reinforced concrete (RC) column has been used to obtain a more economical design by reduction of the material or the self weight of the column. Although a hollow RC column offers a high effectiveness of section properties, it may show poor ductility owing to brittle failure at its inner face. In order to develop a more economical and safer model for a RC column, an internally confined hollow (ICH) RC column and its non-linear concrete model were proposed with the considerations of confining effects. To determine the relation of stress –strain for the concrete in an ICH RC column, possible failure modes of the column were investigated and the confining pressure was derived from equilibriums for each failure mode. A computer program was developed with respect to the derived equilibrium equations and parametric studies were performed to evaluate the application of the developed program. The ICH RC column significantly improved its strength and ductility by the internal confinement.
MCR03-Performance of A DSCT Column under Lateral Loading-Analysis.pdf
An analytical model of a double-skinned composite tubular (DSCT) column was developed and verified using test results. The experimental results demonstrated the rigour and the validity of the present analytical model. Brief parametric studies were carried out for DSCT columns. The developed model considered the confining effect and material non-linearity of concrete. By the buckling or yielding condition of the inner tube of a DSCT column, its failure mode and concrete model were defined. The strength of concrete, the hollow ratio of a DSCT column, and the thickness of an inner tube were selected as the main parameters that affect the behaviour of a DSCT column. The analysis results showed that concrete strength and the thickness of the inner tube affect the axial strength and moment capacity of the column, while the hollow ratio affects only its axial strength.
Off Line Final – Experimental study on the lateral behavior of DSCT columns.pdf
A double-skinned composite tubular column with a corrugated internal tube (DSCT-CT) was suggested to reduce the thickness of the inner tube while maintaining the required buckling strength. The DSCT-CT was studied to evaluate its behavior under lateral loading, and its lateral behavior was compared with that of a DSCT column with a flat internal tube (DSCT-FT). Quasi-static tests were performed by applying cyclic lateral loadings to the two different DSCT columns. Their test results were compared to each other and to those of a solid RC column from other research. The test results showed that the DSCT-CT column had larger ductility than the DSCT-FT column, with an equivalent damping ratio. However, the DSCT-CT column showed a smaller bending moment resistance and energy absorbing capacity than the DSCT-FT column. Overall, the test results showed that the performances of the DSCT columns were superior to that of the solid RC column in terms of strength, yield energy, ultimate energy, and energy absorbing capacity. As a result of their superior moment capacities, the DSCT columns absorbed about 50 % more energy than the solid RC column. However, the DSCT columns showed lower energy ductility factors than the solid RC column because of their high yield energies.
WAS_21-6_02_최종(727-753).pdf
A double-skinned composite tubular (DSCT) wind power tower was suggested and automatic section design software was developed. The developed software adopted the nonlinear material model and the nonlinear column model. If the outer diameter, material properties and design capacities of a DSCT wind power tower are given, the developed software performs axial force-bending moment interaction analyses for hundreds of sections of the tower and suggests ten optimized cross-sectional designs. In this study, 80 sections of DSCT wind power towers were designed for 3.6 MW and 5.0 MW turbines. Moreover, the performances of the 80 designed sections were analyzed with and without considerations of large displacement effect. In designing and analyzing them, the material nonlinearity and the confining effect of concrete were considered. The comparison of the analysis results showed the moment capacity loss of the wind power tower by the mass of the turbine is significant and the large displacement effect should be considered for the safe design of the wind power tower.
응용 관련
01 Effect of Welding Heat on a Precast Steel Composite Hollow Columns.pdf
Steel composite hollow columns have been studied in order to ease their construction. Welding or bolting are mostly used for connecting the steel tubes of precast steel composite hollow columns. However, welding generally results in temperatures of about 20000℃ in the welding zone and 1300℃ around the welding zone. Thus, the strength of the concrete in regions close to a welding zone is reduced. In this paper, the effects of arc welding and electro-slag welding ─two widely used methods for connecting the column modules of steel composite hollow columns─ on the temperature change in the welding zone are studied by performing heat transfer analysis. The changes in the strength of the concrete are investigated for each welding method. The rate of decrease in concrete strength due to electro-slag welding was greater than that due to arc welding. In addition, an effective method using ceramic fibres is suggested for preventing strength reduction in concrete due to welding heat.
02 Fire Resistance Performance of Steel Composite Hollow RC Column with Inner Tube under ISO 834 Standard Fire.pdf
An internally confined hollow RC (ICH RC) column offers strong and durable confinement owing to the reinforcement provided by the inner tube. The strength and ductility of the column are enhanced because of the continuous confining stress provided by the inner tube. The excellent structural perfomance of ICH RC columns make them particularly suitable for applications in high-rise buildings. However, if a high-rise building is damaged by fire, it will collapse without fire resistance performance. Also, lack of evacuation measures endangers human life. Thus, to predict the status of structures in fires, their behaviout should be evaluated in terms of fire time. In this study, the fir resistance performance of an ICH RC column was analysed during an ISO 834 standard fire and with certain initial conditions. Furthermore, the effects of hollow ratio, thickness of inner tube and thickness of cover concrete on the fire resistance performance were analysed. The results could be used for designing fire-resistant ICH RC columns.
Confining effect of concrete in double-skinned composite tubular columns.pdf
A double-skinned composite tubular (DSCT) column, which consists of concrete and inner and outer tubes, was finally developed to overcome the weaknesses of concrete filled tube columns by reducing the self-weight of the column and confining the concrete triaxially. Research pertaining to the stiffness and strength of the column and the confining effect in a DSCT column has been carried out. However, detailed studies on the confining stress, especially the internal confining stress in a DSCT column, have not been carried out. Internal and external confining stresses should be evaluated to determine the effective confining stress in a DSCT column. In this paper, the confining stresses of concrete before and after insertion of an inner tube were studied using finite element analysis. The relationship between the internal or external confining stresses and the theoretical confining stress was investigated by parametric studies. New modified formulae for the yield and buckling failure conditions based on the formulae suggested by former researchers were proposed. Through analytical studies, the modified formulae were verified to be effective for economic and reasonable design of the inner tubes in a DSCT column under the same confining stress.
Fire resistance of double-skinned composite tubular.pdf
Double-skinned composite tubular (DSCT) columns consisting of concrete cast between outer and inner tubes have been developed to overcome certain limitations of other columns, such as the large self weight of concrete-filled tubular columns and lack of concrete confinement of hollow concrete filled tubular columns. The strength and ductility of the column are enhanced by the continuous confining stress provided by the inner tube. Their excellent structural performances make them particularly suitable for applications in high-rise buildings. However, if a high-rise building is damaged by fire, the economic costs associated with building repair can be high. It is very important to put the fire damaged building back into service with the minimum post fire repair. Thus, to predict the status of a structure under fire, its behavior should be evaluated based on the fire duration. Studies on the fire resistance of DSCT columns have been carried out for this purpose. However, they have involved the performance of the entire system without considering the effects of the DSCT column’s components on the fire resistance. In this paper, the behavior of a DSCT column is investigated under an ISO-834 standard fire using an analytical method. The evaluation method for the fire resistance of a DSCT column utilizes a thermal analysis and Eurocode. In addition, the relationship between the DSCT column’s components and the fire resistance is investigated, considering the confining effect. Moreover, the behavior of the DSCT column is evaluated through parametric studies of the hollow ratio, thickness of the outer tube, and thickness of the inner tube.
Fire resistance of double-skinned composite tubular.pdf
An internally confined hollow reinforced concrete (ICH RC) column offers strong and durable confinement by the reinforcement of the inner tube. When the concrete in an ICH RC column experiences axial pressure, an inward radial pressure is produced by the arching action. This radial pressure is resisted by the concrete and the inner tube. Previous research considered the outer pressure and inner pressure to be equal. However, the inner pressure acting on the inner tube is lower because it is partially resisted by the concrete. Therefore, to determine the optimum confining effect on the concrete by the confining condition, it was necessary to determine reasonable values for the inward and outward confining stress in ICH RC columns. In the current study, the confining effects of concrete in an ICH RC column were investigated and evaluated using finite-element (FE) analysis. Parametric studies were performed to determine the factors affecting the confinement of the core concrete in an ICH RC column. The hollow ratio was found to be the main factor affecting the internal confining stress in an ICH RC column. Using the results of FE analysis, estimation equations for the internal confining stress and a new modified equation for the failure condition were developed.
