• 제목/요약/키워드: Opening Load

검색결과 410건 처리시간 0.023초

가공경화지수가 피로균열 지연거동에 끼치는 영향 (Effects of Strain Hardening Exponents on the Retardation of Fatigue Crack Propagation)

  • 김상철;강동명
    • 대한기계학회논문집
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    • 제14권5호
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    • pp.1193-1199
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    • 1990
  • 본 연구에서는 가공경화지수 (n)가 서로 다른 몇가지 재료를 선택하고 과대하 중의 비 (%PL)를 달리하는 단일 과대하중 피로 시험을 행하여 재료의 가공경화지수가 피로 균열 진파의 지연거동에 미치는 영향과 아울러 균열닫힘현상과의 관계를 구명하였다.

축소모형을 이용한 지붕담수시스템을 활용한 아트리움 실내의 냉각효과에 관한 연구 (The Study on the Cooling Effects of the Atrium Interiors for the Roof Watering System by a Scaled Model)

  • 정유근
    • KIEAE Journal
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    • 제9권6호
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    • pp.51-56
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    • 2009
  • The most important advantages of atrium buildings are to allow the abundant natural lighting and outside views. However, the abundant lighting frequently causes to increase a cooling load in summer. The roof watering systems are useful to reduce the cooling load and save the energy. This study aims to investigate the effects of the roof watering system in atrium through the scaled model experiments. For the study, the 1/20 scaled model was made and tests were performed under the clear sky conditions through August 24 to september 7 in 2008. The model size was $45{\times}45{\times}60(cm)$ and depth of roof water was 3(cm). As results, the thermal effects of two types of atrium(roof opening, and roof and front opening,) were evaluated through the experimental points and conditions. It is expected to use the results for the next research to develop the practical roof watering systems for atrium.

중간격벽의 형상을 고려한 상자형 거동에 대한 실험적 연구 (An Experimental Study on Behavior of Box Girder considering Middle Diaphragm Shapes)

  • 정희효;이승열
    • 한국전산구조공학회논문집
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    • 제15권3호
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    • pp.501-510
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    • 2002
  • 상자형의 중간격벽은 상자형의 단면변형을 구속하고 상부플랜지에서 발생되는 하중을 양측의 웨브에 분포시키는 역할을 한다. 그러나 상자형의 내부공간이 중간격벽으로 차단될 경우 내부공간을 활용할 수 없으며 유지관리에 많은 어려움을 격게 된다. 상자형의 격벽이 개구부를 갖는 경우 개구부가 없는 경우에 비하여 어떠한 영향을 갖는지를 실험을 통하여 중간격벽의 강성으로 표현하고자 하였다

개구부가 있는 강판콘크리트 벽체의 압축특성 분석 (Analysis of Compression Characteristics of the Steel Plate-Concrete Wall Structures with Openings)

  • 최병정
    • 한국강구조학회 논문집
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    • 제24권3호
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    • pp.245-256
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    • 2012
  • 본 연구는 SC 벽체의 구조적 성능에 개구부가 주는 영향을 평가하는 목적으로 하였다. SC구조의 실험체는 개구부가 있는 실험체와 없는 실험체로 구분하였으며 개구부형상은 정사각형으로 개구부 주변의 보강과 비보강 그리고 슬리브두께를 변수로 계획하였다. 실험체의 공통된 파괴양상은 강판의 좌굴이 스터드와 스터드 사이에서 발생한 후 콘크리트의 균열이 진행되는 형태이며 개구부의 파괴형태는 수직 슬리브 벽이 개구부 안쪽으로 좌굴되는 파괴형태를 보여주었다. 또한 개구부의 슬리브 유무에 따라 강판좌굴 하중은 비슷하지만 최대압축강도는 슬리브가 있는 것이 크게 나타났다.

유공판의 좌굴강도에 관한 연구 (A Study on the Buckling Strength of Plate Panels with Opening)

  • 김을년;최익흥;권진칠;백점기
    • 대한조선학회논문집
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    • 제47권2호
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    • pp.210-224
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    • 2010
  • The aim of the present study is to investigate the buckling strength of plates and stiffened panels with opening under transverse thrust and shear actions. It is observed that the existing design formulation for critical-buckling strength of plates are not valid for perforated plates, because the current design formulation trends can significantly overestimate or underestimate the load-carrying capacity of plates when plates have large opening and/or are thick. A series of eigen value and elastic.plastic large deflection finite element analyses are carried out with varying the aspect ratio of plate, the opening size and location on plate until and after the ultimate strength is reached. Based on the results obtained from the present study, closed-form design formulations for the elastic buckling strength of plates and stiffened panels with opening are derived. The derived design formulations are considered plasticity correction of the material and verified by experimental tests and results of nonlinear finite element computations.

Strengthening of Cutouts in Existing One-Way Spanning R. C. Flat Slabs Using CFRP Sheets

  • Shehab, Hamdy K.;Eisa, Ahmed S.;El-Awady, Kareem A.
    • International Journal of Concrete Structures and Materials
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    • 제11권2호
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    • pp.327-341
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    • 2017
  • Openings in slabs are usually required for many different applications such as aeriation ducts and air conditioning. Opening in concrete slabs due to cutouts significantly decrease the member stiffness. There are different techniques to strengthen slabs with opening cutouts. This study presents experimental and numerical investigations on the use of Carbon Fiber Reinforced Polymers (CFRP) as strengthening material to strengthen and restore the load carrying capacity of R.C. slabs after having cutout in the hogging moment region. The experimental program consisted of testing five (oneway spanning R.C. flat slabs) with overhang. All slabs were prismatic, rectangular in cross-section and nominally 2000 mm long, 1000 mm width, and 100 mm thickness with a clear span (distance between supports) of 1200 mm and the overhang length is 700 mm. All slabs were loaded up to 30 kN (45% of ultimate load for reference slab, before yielding of the longitudinal reinforcement), then the load was kept constant during cutting concrete and steel bars (producing cut out). After that operation, slabs were loaded till failure. An analytical study using finite element analysis (FEA) is performed using the commercial software ANSYS. The FEA has been validated and calibrated using the experimental results. The FE model was found to be in a good agreement with the experimental results. The investigated key parameters were slab aspect ratio for the opening ratios of [1:1, 2:1], CFRP layers and the laminates widths, positions for cutouts and the CFRP configurations around cutouts.

바닥판 적용 초고성능 시멘트 복합체의 인장응력-균열개구 관계 (Tensile Stress-Crack Opening Relationship of Ultra High Performance Cementitious Composites(UHPCC) Used for Bridge Decks)

  • 권승희;이승국;박성용;조근희;조정래
    • 한국구조물진단유지관리공학회 논문집
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    • 제17권1호
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    • pp.46-54
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    • 2013
  • 실제 교량의 바닥판에 적용할 목적으로 섬유의 길이 및 혼입량을 달리한 두 가지 초고성능 시멘트 복합체를 고려하고 있다. 이 연구의 목적은 이 두 재료의 균열저항성을 평가하는 것이다. 두 재료에 대한 휨인장 파괴실험을 수행하였고, 실험으로부터 얻은 하중-균열개구변위 관계를 최적으로 모사하는 인장응력-균열개구 관계를 역해석을 통해 파악하였다. 역해석결과 13 mm 길이의 섬유를 2% 함유한 UHPCC는 16.3 mm와 19.5 mm 길이의 섬유를 각각 0.5%와 1.0% 함유한 UHPCC에 비해 파괴에너지가 작은 것으로 나타났다. 균열을 보다 분산시키고 균열폭을 감소시키기 위해서는 길이가 긴 두 종류의 섬유를 혼용한 UHPCC를 사용하는 것이 바람직할 것으로 판단된다.

초기재령 콘크리트의 파괴특성 (Fracture Characteristics of Concrete at Early Ages)

  • 이윤;김진근
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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    • pp.215-220
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    • 2001
  • The objective of this study is to examine the fracture characteristics of concrete at early ages such as critical stress intensity factor, critical crack-tip opening displacement, fracture energy based on the concepts of the effective-elastic crack model and the cohesive crack model. A wedge splitting test for Mode I was performed on cubic wedge specimens with a notch at the edge. By varying strength and age, load-crack mouth opening displacement curves were obtained and the results were analyzed by linear elastic fracture mechanics. The results from the test and analysis showed that critical stress intensity factor and fracture energy increased, and critical crack-tip opening displacement decreased with concrete age from 1 day to 28 days. The obtained fracture parameters at early ages may be used as a fracture criterion and an input data for finite element analysis of concrete at early ages.

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농촌지역의 조적조 건축물의 내진성능 개선을 위한 구조적 보강법 제안에 관한 연구 (A Study on Structural reinforcement suggestions for improvement of Seismic Performance of Masonry Buildings in rural areas)

  • 이덕용;김일중
    • 한국농촌건축학회논문집
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    • 제15권4호
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    • pp.51-58
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    • 2013
  • This study Masonry Buildings in rural areas, due to the lateral load resistance for seismic reinforcement method is proposed. Some of the proposed methods for reinforcement directly through finite element analysis to evaluate the change in frequency. The results for the following: This paper has the object of investigating natural frequencies of opening thick plates on Pasternak foundation by means of finite element method and providing Kinematic design data for mat of building structures. In this paper, vibration analysis of rectangular opening thick plate is done by use of Serendipity finite element with 8 nodes by considering shearing strain of plate. It is shown that natrural frequencies depend on not only Winkler foundation parameter but also shear foundation parameter, opening position.

개선된 참조응력법을 이용한 복합균열이 존재하는 배관의 균열개구변위 계산 (Crack Opening Displacement Analysis of Complex Cracked Pipes based on Enhanced Reference Stress Method)

  • 허남수;김윤재;김영진
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2001년도 추계학술대회논문집A
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    • pp.80-86
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    • 2001
  • An engineering estimation equation for the crack opening displacement (COD) is proposed for a complex cracked pipe, based on the reference stress approach. To define the reference stress, a simple plastic limit load analysis for the complex cracked pipe subjected to combined bending and tension is performed considering the crack closure effect in the compressive-stressed region. Comparison with ten published test data and the results from existing method shows that the present method not only reduces non-conservatism associated with the existing method, but also provides consistent and overall satisfactory results.

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