• Journal of Korean Society of Steel Construction
• /
• v.29 no.3
• /
• pp.205-215
• /
• 2017

This study presents an example of conceptual design for hollow circular section multi-column tower system subjected to 10MW level wind load by introducing a method based on member utilization that examine both structural stability and economical efficiency. The basic assumptions for the proto type of a multi-column tower that can replace a single-cylinder tower were suggested and structural models were constructed following the assumptions and analyzed for identifying member forces. Based on the calculated member strengths and acting loads, the member utilization of the proposed multi-column tower structures were calculated for axial force, shear, bending and torsion and evaluaed for suitability as a wind tower. Design parameters such as steel tube dimensions, slenderness ratio, and number of floors for braces was proposed in the acceptable range of member utilization for conceptual design of multi-column wind towers.

• 한국방재학회:학술대회논문집
• /
• 2011.02a
• /
• pp.40-40
• /
• 2011

현재 일반적으로 활용되고 있는 원통형 쉘구조로 이루어진 타워구조의 대형화가 추진되면서 제작, 운반 편의성, 단면효율성, 경제성 제고를 위해 다각형단면 기둥구조물의 활용이 대두되고 있다. 하지만 다각형 단면 기둥구조의 극한강도에 대한 자료가 충분치 않고 관련 기준이나 지침이 명확히 제시되고 있지 않은 실정이다. 본 연구에서는 원통형 쉘구조물을 다각형구조물로 대체하여 제작될 경우 축방향 압축에 대한 내하력 향상 효과를 수치해석적으로 검토해 보고자 한다. 해석모델은 지름 2m, 두께 20mm인 원형강관 프로토타입 풍력타워 구조를 참고로 하여 이에 내접하도록 결정한 6~12각형 단면 형상으로써 높이 10,000mm인 3차원 기둥모델을 구현하였고 유한요소프로그램인 ABAQUS를 이용하여 해석하였다. 각 subpanel의 중앙에 종방향 보강재를 설치하였을 때 국부좌굴에 대한 내하력 변화를 비교하기 위해 종방향보강재로 보강한 모델을 구성하여 비교 해석을 수행하였다. 종방향 보강재의 제원은 미국 SSRC 제안식을 기준으로 삼았다. 탄성좌굴해석을 통해 탄성좌굴모드 형상을, 비선형비탄성해석을 통해 최종파괴모드 및 극한강도를 얻었다. 보강 전 후의 탄성좌굴 해석 결과로부터 최소모드의 고유치 값을 비교하였다. 각 subpanel 단면 중심부에 한 개의 보강재를 설치한 경우 탄성좌굴강도가 4배 가량 증가하였다. 이로부터, 보강재(n=1) 설치에 따라 유효 폭두께비가 1/2로 감소하는 효과를 확인 할 수 있다. 비선형해석결과로부터 subpanel의 단면중심에 보강재를 설치한 경우 보강재가 위치한 곳에 고정점이 형성되어 이를 중심으로 국부 좌굴모드에 변화가 생기는 것이 확인되었다. 이러한 변화는 다각형 단면 기둥구조의 내하력 성능, 즉 국부좌굴강도에 영향을 준다. 충분한 강성을 갖는 종방향 보강재가 설치된 경우, 극한상태에서도 유효폭두께비가 줄어드는 것과 같은 강도 향상 효과를 확인할 수 있다. 이러한 사실은 각 해석결과 극한강도를 DIN code, Migita와 Fukumoto의 제안식, SSRC 설계제안식 등과의 비교를 통해 확인할 수 있었다.

• Journal of Korean Society of Steel Construction
• /
• v.27 no.2
• /
• pp.219-229
• /
• 2015

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.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.25 no.5
• /
• pp.397-404
• /
• 2012

Fragility curves show the probability of a system reaching a limit state as a function of some measure of seismic intensity. To obtain fragility curves of six and twelve story staggered wall structures with middle corridor, incremental dynamic analyses were carried out using twenty two pairs of earthquake records, and their failure probabilities for various intensity of seismic load were investigated. The performances of staggered wall structures with added columns along the central corridor and the structures with their first story walls replaced by columns were compared with those of the regular staggered wall structures. Based on the analysis results it was concluded that staggered wall structures with central columns have the largest safety margin for the same level of seismic load.

• Korean Architects
• /
• no.8 s.388
• /
• pp.85-91
• /
• 2001

10년도 넘었을까 모처럼 유럽을 여행할 기회가 있었다. 우리나라는 온 국토가 공사장이나 진배없던 시절이라 그곳의 풍경이 오히려 이채로웠다. 자동차를 타고 한참을 가야 그것도 별로 크지 않은 공사장을 볼 수 있었고, 그나마 신축공사 보다는 오래된 건물을 보수하는 것들이 더 많았다. 더구나 희한한 것은 대로에 면한 고색 창연한 건물의 외벽만을 텔레비전 세트처럼 남겨두고 그 뒤편에서는 전혀 새로운 공사를 하는 것도 눈에 들어왔다. 조상들의 유적을 외관만이라도 보존하도록 법제화되었으므로 여기저기 떨어져 위치한 100년도 넘은 집에다 따로따로 최신형 공작기계를 설치한 공장에서 제품을 생산하는 비능률을 감수하는 것도 볼 수 있었다. 물론 변두리 신시가지에서는 현대 감각이 물씬한 건물도 신축하고 있었는데, 대체로 리모델링 사업규모가 전체 건축 물량의 50% 정도는 될 것이라는 설명이었다. 필자는 그때 우리도 머지 않아 그런 시절이 도래할 것이라는 확신이 있었다. 더구나 그들의 건물들이 100년 이상을 버티는데 반하여 우리네 것들은 수명이 고작 20~30년 밖에 되지 못할 정도로 부실하기 때문이다. 그때부터 기존 건물의 내력 부족분을 보완하고 용도를 변경하거나 증축을 할 때 어떤 방법이 합리적일까 하는 것에 관심을 가지고 연구하게 되었다. 바닥 슬래브나 보를 잘라버리거나 새로 덧붙이기도 하고 심하면 기둥을 솎아낼 필요가 있을 수도 있다. 그러나 유감스럽게도 대부분의 경우는 그동안 열심히 고안한 방식을 실무현장에 적용할 수 있도록 받아들이는 당사자가 별로 없었다. 첫째 이유는 처음하는 일이라 말하자면 겁이 난다는 것이고, 둘째로는 새로운 방식을 믿고 시행하려 해도 실제로 책임지고 시공하겠다고 나서는 업체를 만날 수 없어서였다. 그래서 그동안 설계뿐만 아니라 시공까지 일일이 간섭하여 어렵게 시행했던 현장 경험들을 소개하여 앞으로 비슷한 조건을 만날 경우 참고할 수 있게 한다. 우선 기둥을 솎아 내는 것을 알아보고 앞으로 기둥, 보, 슬래브, 기초 등의 새로운 보강방법을 소개하고자 한다.

• Korean Journal of Heritage: History & Science
• /
• v.43 no.2
• /
• pp.40-59
• /
• 2010

Anssolim is the unique technique which standing columns lean in a inward direction of buildings in traditional architecture, which has not been thoroughly investigated to this day. With a dearth of previous studies, the anssolim technique can only be examined through detailed three-dimensional surveys. The main halls of Korean palaces can be seen as buildings that were built with the regulations of the day in mind, making them excellent research subjects when studying the anssolim technique. The findings can be summarized as follows. 1. In the main halls that were studied, anssolim was applied most to main space (eokan) columns, then lessened for peripheral columns. 2. The largest second-floor cheoma columns were placed inward in the eokan, then became smaller as with the peripheral columns. In the case of the eokan, the columns were arranged according to the size of the anssolim. 3. The second-floor cheoma column anssolim in the middle-floor main hall were generally a third or a quarter of the size of those on the first floor. As on the first floor, the largest anssolim were applied to the eokan columns, then became gradually smaller towards the periphery columns. 4. In the palace main halls, the largest anssolim were used for the eokan columns, and became smaller with the peripheral columns. This unique structure can be seen to be a Korean technique that deviates from the Chinese "Yingzaofashi(營造法式)" techniques. Although this study is limited in that it only studies the main hall of Korean palaces, it is significant in that it shed new light on the technological implications of the anssolim technique, and can be used as important data for research into the history of technology. Although this type of data is difficult to extrapolate, it has been made as accurate as possible by minimizing the margin of error in the data for the palaces that were actually studied.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.31 no.6
• /
• pp.293-299
• /
• 2018

Steel truss outriggers can be replaced by reinforced concrete walls to control the lateral drift of tall buildings. When reinforced concrete outrigger walls are connected to perimeter columns, not only axial forces but also shear forces and moments can be induced on the perimeter columns. In this study, the shear force of the perimeter column due to the rotation of the outer edge of the outrigger wall is derived as analytic equations and the result is compared with the finite element analysis result. In the finite element analysis, the effects of connecting beams at each floor and the effect of modeling shear walls and outriggers with beam element and plane stress element was analyzed. The effect of the connecting beam was almost negligible and the plane stress element was determined to have greater stiffness than the beam element. The inter-story rotation and the shear force of the perimeter column due to the rotation of the outer edge of the outrigger wall was considerably smaller than the allowable value. Therefore, even if the outrigger wall made of reinforced concrete is applied to a tall building, it is considered that there is no need to study the shear force and moment induced in the perimeter columns.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.15 no.3
• /
• pp.1764-1769
• /
• 2014

Numerical investigations have been conducted on the junction that connect the multi-tubular section and the single shell section in order to evaluate applicability of hybrid sections in wind turbine towers instead of conventional single shell towers. Major characteristics in structural details include extension of multi-tubular member into shell end section, installation of wing stiffeners, and different layout of floor beams. Elastic and nonlinear incremental analyses were conducted to examine stress concentration patterns and ultimate behaviors, respectively. Based on evaluation of structural performance due to vertical and horizontal forces, it has been confirmed that installation of floor beams and wing stiffeners sensitively affect ultimate strength of global wind tower.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.41 no.6
• /
• pp.443-453
• /
• 2017

In flip chip technology, the conventional solder bump has been replaced with a copper (Cu) pillar bump owing to its higher input/output (I/O) density, finer pitch, and higher reliability. However, Cu pillar bump technology faces several issues, such as interconnect shorting and higher low-k stress due to stiffer Cu pillar structure when the conventional reflow process is used. Therefore, the thermal compression bonding (TCB) process has been adopted in the flip chip attachment process in order to reduce the package warpage and stress. In this study, we investigated the package warpage induced during the TCB process using a numerical analysis. The warpage of the TCB process was compared with that of the reflow process.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.14 no.4
• /
• pp.61-71
• /
• 2010

Five half-scale beam-to-column connections in a precast concrete frame were tested with cyclic loading that simulated earthquake-type motions. Five half -scale interior beam-column assemblies representing a portion of a frame subjected to simulated seismic loading were tested, including one monolithic specimen and four precast specimens. Variables included the detailing used at the joint to achieve a structural continuity of the beam reinforcement, and the type of special reinforcement in the connection (whether ECC or transverse reinforcement). The specimen design followed the strong-column-weak-beam concept. The beam reinforcement was purposely designed and detailed to develop plastic hinges at the beam and to impose large inelastic shear force demands into the joint. The joint performance was evaluated on the basis of connection strength, stiffness, energy dissipation, and drift capacity. From the test results, the plastic hinges at the beam controlled the specimen failure. In general, the performance of the beam-to-column connections was satisfactory. The joint strength was 1.15 times of that expected for monolithic reinforced concrete construction. The specimen behavior was ductile due to tensile deformability by ECC and the yielding steel plate, while the strength was nearly constant up to a drift of 3.5 percent.