근거리 및 원거리 지진에 대한 비선형 구조물의 강도감소계수 산정

송종걸(Song Jong-Keol),김학수(Jin He-Shou) 대한토목학회 2007 대한토목학회논문집 A Vol.27 No.3A

강도감소계수는 탄성설계 스펙트럼으로부터 비탄성 설계스펙트럼을 작성하는데 사용되며, 구조물이 가진 연성도 능력 한도 내에서 비탄성 거동을 허용함으로써 설계강도를 어느 정도 낮출 수 있는지를 나타내는 척도이다. 기존의 많은 연구자들이 제안한 강도감소계수 제안식은 대부분 탄소성 모델과 제한적인 지진하중에 대하여 작성되었다. 그러므로 본 연구에서는 강도감소계수에 관한 계산식의 활용성 및 유용성을 증대시키기 위하여, 근거리 및 원거리 지진으로 구분되는 총 80개 지진가속도 기록을 사용하여 강도감소계수를 평가하였으며, 구조물의 비탄성 이력거동은 이선형 및 강성저하 모델로 구분하여 적용할 수 있는 강도감소계수를 제안하였다. 또한 강도감소계수에 대한 변위연성도, 항복후 강성비, 구조물의 주기, 비탄성 이력모델과 지진 특성의 영향을 분석하였다. 본 연구에서 제안한 강도감소계수의 정확성은 기존의 제안식과 비탄성 응답스펙트럼 해석에 의해 계산된 강도감소계수와의 비교에 의하여 평가하였다. Strength reduction factor is used to estimate inelastic strength demands from elastic strength demands. The strength reduction factor represents a reduction degree of design strength by permitting inelastic behaviors within the limited ductility capacity. Most of existing formulas for strength reduction factor were mainly constructed for the elasto-plastic model and limited numbers of earthquake records. In order to improve application and usefulness of simple formula for the strength reduction factor, two hysteretic models and 80 earthquake records are used in the inelastic response spectrum analysis. Two hysteretic models used are the bilinear and stiffness degrading models. In order to reflect characteristics of earthquakes, the 80 earthquake records are classified into two groups of 40 far-field and 40 near-field earthquake records. The effects of several parameters such as displacement ductility, strain hardening ratio, period, characteristics of earthquakes and hysteretic models for the strength reduction factor are evaluated. Accuracy of the proposed formula is evaluated by comparing the strength reduction factors estimated by existing and proposed formulas with those calculated from inelastic response spectrum analysis.

유연 디스크 커플링의 비틀림 강성을 고려한 강성감소계수 산정

박형준,강효림,한승호 대한기계학회 2022 大韓機械學會論文集A Vol.46 No.11

Flexible disc couplings are used to smoothly transmit rotational powers between two shafts. Although the theoretical method proposed in the AGMA standard has been used to evaluate the torsional stiffness of couplings, it is challenging to accurately calculate the torsional stiffness owing to the out-of-plane deformation in the flexible disc pack. In this study, finite element models of two flexible disc couplings with different shapes, sizes, and torque capacities were established, in which the frictional conditions enabled the separation of contact surfaces for the flexible disc pack. The results of the finite element analysis showed that significant warping and out-of-plane deformation occurred in the flexible disc pack and increased the torsional angular displacement of the coupling. By comparing the torsional stiffness obtained from the theoretical and numerical results, the torsional stiffness reduction factors for the coupling were assessed and verified experimentally. 유연 디스크 커플링은 동력전달장치에서 오정렬을 허용하는 동시에 회전동력을 원활하게 전달하기 위해서 사용된다. 커플링의 비틀림 강성을 평가하기 위해서 AGMA 규격에서 제안한 이론식이 사용되고 있으나, 적층된 디스크 유연부재의 면외변형 거동으로 정확한 강성평가가 불가능하다. 본 연구에서는 형상, 크기 및 토크 용량이 서로 다른 두 유연 디스크 커플링을 대상으로, 적층된 얇은 디스크 간의 접촉 분리가 가능한 마찰조건을 구현하여 유한요소 모델을 구축하였다. 유한요소 해석 결과 비틀림 하중에 의해 압축 응력이 디스크 팩에 작용하면서 뒤틀림이 유발되고, 접촉면이 이탈되는 면외변형이 현저히 나타났다. 이는 여러 겹의 얇은 판으로 구성된 디스크 팩의 비틀림 각 변형에 큰 영향을 미쳐 제안된 커플링의 비틀림 강성을 현저하게 감소시켰다. 유한요소 해석을 통해 얻어진 결과를 이론식과 비교하여 디스크 유연부재에 의한 비틀림 강성감소계수를 산정하였고, 아울러 비틀림 시험을 수행하여 이의 정도를 평가하였다.

하중 특성에 기초한 무량판 슬래브의 강성감소 계수

최정욱,송진규 대한건축학회 2005 大韓建築學會論文集 : 構造系 Vol.21 No.1

The flexural stiffness of flat slabs is reduced by cracking due to externally applied loads and volume changes To reflect this phenomenon in an effective beam width model, the stiffness reduction factor, which is equal to the effective slab stiffness divided by the gross slab stiffness, is commonly used Many techniques for defining the stiffness reduction factor have been proposed However, these methods fat! to sufficiently explain the various stiffness changes of the actual slab To solve this problem, a detailed study on the stiffness reduction factor is performed, assuming that flexural stiffness of members is Inversely proportional to deflection In the study, the slab stiffness reduction caused not only by service gravity loads but also due to the combined effects of creep and shrinkage is mainly considered Based on the results, the methods for calculating the stiffness reduction factor of flat slabs based on loading characteristics are developed The proposed methods are verified by comparisons With the experiments with multi-panel and the analysis models with stiffness reduction

횡하중하의 포스트 텐션 플랫 플레이트 해석을 위한 강성감소계수

박영미(Young-Mi Park),박진아(Jin-Ah Park),한상환(Sang-Whan Han) 한국콘크리트학회 2009 콘크리트학회논문집 Vol.21 No.5

조합하중을 받는 무량판 구조의 강성감소 계수

최정욱(Choi Jung-Wook),윤정배(Yoon Jeong-Bae),송진규(Song Jin-Gyu) 대한건축학회 2003 大韓建築學會論文集 : 構造系 Vol.19 No.6

Cracking of slabs would be caused by applied loads and volume changes during the life of a structure. And it reduces flexural stiffness of slabs and increases lateral flexibility. Thus, a stiffness reduction phenomenon due to slab cracking must be considered in stiffness assumptions for lateral drift calculations. A combined analytical and experimental study about the stiffness reduction factor of slabs in a flat plate structure is conducted. In analytical study, the stiffness reduction factor is changed by the magnitude of gravity loads and column spans, but its variation is much reduced by lateral loads. The stiffness reduction factor for combined loads ranges from a half to a quarter. This range matches the commentary specified in ACI 318-02. A test of nine-connection flat plate frames constructed at fifty percent of full scale is undertaken. This test provides data on lateral response at the service gravity load level. Based on a 0.2 percent drift criterion for building serviceability and a 0.5 percent drift criterion for story safety, the comparisons between test results and analysis results using the effective beam width model are performed. The experimental study shows that the stiffness reduction of the interior connection is much smaller than the stiffness reduction of the other connections, and the effective beam width model with a constant stiffness reduction factor of one-third gives a close stiffness estimate for the test structure.

골조 안정성 평가를 위한 직접해석법의 적용 방법에 따른 영향

김희동 한국강구조학회 2010 韓國鋼構造學會 論文集 Vol.22 No.4

The purpose of this study was to evaluate the influence of the methods of application of the direct analysis method, using the load amplification factor suggested by the KBC 2009 design code, for the evaluation of frame stability. For this purpose, the direct analysis method was performed for three-story-one-bay and five-story-three-bay unbraced steel frames with various notional loads, bending stiffness reductions, and factor B2s. The results of the analyses were compared with the results of the second-order inelastic analysis to evaluate the influence of the applied methods. The scale of the frame, the axial load ratio, and the axial load distribution pattern were added to the main parameters to investigate the external effects. The research results showed that the influence of the methods of application of the direct analysis method is not significant in the case of the required axial strength and the application of the additional notional loads; and that the application of the factor B2 with the story stiffness concept to the direct analysis method is appropriate for the required flexural strength. 본 연구는 강구조 설계기준(KBC 2009)에서 골조 안정성 평가를 위해 제시한 하중증폭계수를 적용한 직접해석법의 적용 방법에 따른 영향을 해석적 방법을 통해 평가하는데 목적이 있다. 이를 위해 KBC 2009에서 제안하고 있는 가상수평하중 적용 방법, 휨강성 감소 방법,B2 계수 산정 방법 등을 각각 적용한 직접해석을 3층 1스팬 및 5층 3스팬 비가새 강구조 골조에 대해 실시하고, 그 해석 결과를 2차 비탄성 해석 결과와 비교하여 각 적용 방법의 영향을 평가하였다. 직접해석법 적용 방법 이외에 외적 요인의 영향을 고찰하기 위해 골조의 규모, 기둥의 축력비, 축력의 층별분포 등도 변수로 추가하였다. 연구 결과 소요압축강도는 직접해석법 적용 방법에 따른 차이가 크지 않은 것으로 나타났으며, 소요휨강도는 가상수평하중 누계 및 추가 적용, 층강성 개념 B2 계수를 직접해석법에 적용시 적절한 결과를 나타내었다.

수정된 등가골조법을 이용한 포스트 텐션 플랫 플레이트 골조의 해석

박영미(Park Young-Mi),이재주(Lee Jae-Joo),한상환(Sang-Whan Han) 대한건축학회 2009 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.29 No.1(구조계)

In general, Post-Tensioned (PT) flat plate systems have been used as a gravity load resisting system (GLRS) with lateral force resisting system (LFRS) such as shear walls. Thus, GLRS should retain the ability to undergo the lateral drift associated with the LFRS without loss of gravity load carrying capacity. PT flat plate system should be considered internal forces (e.g., unbalanced moments) and lateral deformation generated in vicinity of slab joints render the system more susceptible to punching shear. ACI 318(2008) permits the finite-element method, effective beam width method, and equivalent frame method for flat plate systems under lateral loads. These analysis methods can produce widely different result, and each has advantage and disadvantages. Thus, it is sometimes difficult for a designer to select an appropriate analysis method and interpret the results for design purposes. This study is to verify practicality of the modified equivalent frame method for PT flat plate system under lateral loads. To verify, this study compared analysis results using the modified equivalent frame method with published experimental results of PT flat plate system.

구조용 접합유리의 약축 휨거동 특성에 관한 연구

이문환(Lee Mun-Hwan),허병욱(Heo Byung-Wook) 대한건축학회 2008 大韓建築學會論文集 : 構造系 Vol.24 No.12

This paper describes the results from four-point bending tests on laminated glass beams with PVB and SGP flim. The investigated main variables were the type, the thickness and relative positions of the film. The tests results are presented and discussed, focusing on the structural response in terms of shear transfer capacity, ductility and collapse modes. Test results showed that the stiffness and ductility of the laminates glass beam were considerably effected by flim thickness and positions. Finally, An analytical method to estimate the shear-bond stiffness of the laminated glass beam with PVB and SGP flim is presented.

부분합성 작용을 고려한 강판성형 합성보의 휨거동

허병욱(Heo Byung-Wook) 대한건축학회 2008 大韓建築學會論文集 : 構造系 Vol.24 No.10

This paper describes the effects of shear slip on stiffness and strength of encased steel-concrete composite beams which was recently developed. According to the various current design methods founds in standards and guidelines, the decrease of stiffness due to slip effects are not considered. In previous study, It is derived an exact solution based on the stiffness of shear connectors which is not dependent on the load cases. To validate this approach, the predicted deflection using the proposed method and currently used equations is compared against test results. From the comparison between the calculation method and test results, it showed a good agreement with respect to the stiffiness reduction due to shear slip, within 6%.

철근콘크리트 기둥의 비탄성 전단력-전단변형을 위한 해석모델

도경석(Do, Kyeong-Seok),강석봉(Kang, Suk-Bong) 대한건축학회 2020 대한건축학회 학술발표대회 논문집 Vol.40 No.2