• 제목/요약/키워드: ultimate criterion

검색결과 84건 처리시간 0.019초

인장강성 효과를 고려한 RC 쉘의 재료비선형 해석 (Material Nonlinear Analysis of the RC Shells Considering Tension Stiffening Effects)

  • 진치섭;엄장섭
    • 대한토목학회논문집
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    • 제13권5호
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    • pp.99-107
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    • 1993
  • 본 논문에서는 콘크리트 균열 사이의 인장강성 효과를 고려한 임의의 기하하적 형상을 갖는 철근 콘크리트 쉘을 해석하기 위하여 재료비선형 유한요소 프로그램을 작성하였다. 본 논문은 연속적인 컴퓨터 해석으로 탄성, 비탄성 및 극한 범위에서의 철근과 콘크리트의 응력은 물론, 하중-변위 응답과 균열전파를 추적할 수 있었다. 골재억물림과 철근의 다울작용을 포함하는 유효전단계수를 평가하기 위하여 균열상태의 전단유지계수를 도입하였다. 콘크리트는 인장에서는 취성으로 압축에서는 탄소성으로 가정하였다. 콘크리트의 소성거동은 Drucker-Prager 항복기준과 결합유동법칙에 따르는 것으로 가정하였다. 철근은 Von Mises 항복기준으로 가정하였으며 등가의 두께를 가지는 철근층으로 모델화 하였다. 수치해석을 위하여는 증분형접선강성도 방법을 사용하였다. 수치예제를 제시하여 본 연구결과를 Hedgren의 실험 결과와 Lin의 수치해석과 비교하였다.

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축방향하중에 대한 튜브형 단면겹치기 접착조인트의 전적 파괴모델에 관한 연구 (Failure Model for the Adhesively Bonded Tubular Single Lap Joints Under Static Tensile Loads)

  • 김영구;이수정;이대길
    • 대한기계학회논문집A
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    • 제20권5호
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    • pp.1543-1551
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    • 1996
  • The static tensile load bearing capability of as adhesively-bonded tubular single lap jint that is calculated usign the linear mechanical properties of adhesive is usually far from the experimentally determined because the majority of the load transfer of the adhesively-bonded jointd is accomplished by the nonlinear behavior of the rubber-toughened eoxy adhesive. In this paper, both the nonlinear mechanical properties and the fabrication residual thermal stresses of adhesive were included in the calculation of the stresses of adhesively-bonded joints. The onlinear tensile properties of adhesive were approximated by an exponential form which was represented by the initial tensile modulus and ultimate tensile stength of adhesive. The stress distribution in the adhesive were calculated by applying the load obtained from the tensile tests. From the tensile tests and the stress analysis of adhesively-bonded hoints, the failure model for adhesively-bonded tubular single lap joints was proposed.

브랜드아파트 광고이미지의 기호학적 해석을 통한 광고커뮤니케이션의 효율성에 대한 연구 (A Study of the Efficiency of Advertisement Communication through the Semiological Translation for Advertisement Image of Brand Apartment)

  • 장미경;최정윤
    • 디자인학연구
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    • 제19권4호
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    • pp.145-154
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    • 2006
  • 오늘날 브랜드아파트 광고는 유비쿼터스 도입으로 소비자 편리를 추구하는 하이테크 아파트의 이미지와 소비자의 웰빙 라이프를 강조하는 자연친화적 아파트의 이미지가 주류를 이루고 있다. 그러나 일부 브랜드를 제외하고는 광고이미지 표현에 있어서 차별성이 결여되어 있다고 보여진다. 이것은 광고의 궁극적 목적인 효과적인 커뮤니케이션의 제공에 대한 문제와도 관련이 있을 것이다. 따라서 본 연구는 브랜드아파트 광고의 효율적 커뮤니케이션 방안을 제시하기 위하여, 먼저 최근 브랜드 아파트 광고가 제시하고 있는 이미지들을 기호학적으로 해석하고, 이러한 이미지가 소비자에게 적절하게 전달되고 있는지를 검토하기 위하여 디자인 전문가 집단123명을 대상으로 브랜드 아파트 광고에 대한 이미지 조사를 실시하였다. 그 결과 광고 표현의 기호학적 해석에 있어서는 광고 컨셉과 광고 이미지가 기호학적으로 일치하고 있을 때 의미공유가 이루어지고 있으며, 이러한 의미공유로부터 광고주와 소비자 간의 성공적인 광고 커뮤니케이션 실현이 가능한 것으로 나타났다. 본 연구의 결과를 토대로, 광고 기획에 있어서 기호학의 도입은 효율적인 광고 커뮤니케이션의 제공을 위한 논리적인 판단 기준이 될 수 있음을 알 수 있었다.

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Dynamic experimental study on single and double beam-column joints in steel traditional-style buildings

  • Xue, Jianyang;Qi, Liangjie;Yang, Kun;Wu, Zhanjing
    • Structural Engineering and Mechanics
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    • 제63권5호
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    • pp.617-628
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    • 2017
  • In order to study the failure mode and seismic behavior of the interior-joint in steel traditional-style buildings, a single beam-column joint and a double beam-column joint were produced according to the relevant building criterion of ancient architectural buildings and the engineering instances, and the dynamic horizontal loading test was conducted by controlling the displacement of the column top and the peak acceleration of the actuator. The failure process of the specimens was observed, the bearing capacity, ductility, energy dissipation capacity, strength and stiffness degradation of the specimens were analyzed by the load-displacement hysteresis curve and backbone curve. The results show that the beam end plastic hinge area deformed obviously during the loading process, and tearing fracture of the base metal at top and bottom flange of beam occurred. The hysteresis curves of the specimens are both spindle-shaped and plump. The ultimate loads of the single beam-column joint and double beam-column joint are 48.65 kN and 70.60 kN respectively, and the equivalent viscous damping coefficients are more than 0.2 when destroyed, which shows the two specimens have great energy dissipation capacity. In addition, the stiffness, bearing capacity and energy dissipation capacity of the double beam-column joint are significantly better than that of the single beam-column joint. The ductility coefficients of the single beam-column joint and double beam-column joint are 1.81 and 1.92, respectively. The cracks grow fast when subjected to dynamic loading, and the strength and stiffness degradation is also degenerated quickly.

Comparative field tests on uplift behavior of straight-sided and belled shafts in loess under an arid environment

  • Qian, Zeng-zhen;Lu, Xian-long;Yang, Wen-zhi;Cui, Qiang
    • Geomechanics and Engineering
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    • 제11권1호
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    • pp.141-160
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    • 2016
  • This study elucidates the uplift behaviors of the straight-sided and belled shafts. The field uplift load tests were carried out on 18 straight-sided and 15 belled shafts at the three collapsible loess sites under an arid environment on the Loess Plateau in Northwest China. Both the site conditions and the load tests were documented comprehensively. In general, the uplift load-displacement curves of the straight-sided and belled shafts approximately exhibited an initial linear, a curvilinear transition, and a final linear region, but did not provide a well defined peak or asymptotic value of the load, and therefore their uplift resistances should be interpreted from the load test results using an appropriate criterion. Nine representative uplift resistance interpretation criteria were used to define the "interpreted failure load" for each of the load tests, and all of these interpreted uplift resistances were normalized by the failure threshold, $T_{L2}$, obtained using the $L_1-L_2$ method. These load test data were compared statistically and graphically. For the straight-sided and belled shafts, the normalized uplift load-displacement curves were respectively established by the plots that related the mean interpreted uplift resistance ratio against the mean displacement at the corresponding interpreted criteria, and the comparisons of the normalized load-displacement curves were made. Specific recommendations for the designs of uplift belled and straight-sided shafts in the loess were given, in terms of both capacity and displacement.

생태학적 지식과 관련된 우리나라 환경교육의 실태 분석 (An Analysis for the status of Environmental Education in the light of the Ecological Knowledge in Korea)

  • 박진희;장남기
    • 한국환경교육학회지:환경교육
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    • 제13권1호
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    • pp.65-74
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    • 2000
  • Environmentally literated students and adults should be able to use and apply the basic ecological concepts when considering environmental problems and issues. Because ecology forms the foundation of environmental education, a review of the literatures on the degree of students' understanding for ecological concepts can provide useful insights for environmental educators. The purposes of this study were as follows: first, to analyse the parts connected with ecological knowledge of two environmental education books, ‘environments’(middle school) and ‘environmental science’(high school), second, to investigate the level of understanding on ecological concepts by the use of new developed instrument. The 20 most important ecological concepts from Cherrett(1989) and the important ecological concepts' lists from Hungerford and Volk(1990), Ramsey, Hungerford and Volk(1992), Volk(1993) would be recognized and endorsed by most environmental educators as concepts essential to environmental literacy, We referenced these informations and sequenced ecological knowledge as four main categories(communities, populations, ecosystem, man as a component of the nature systems). We have used it as a criterion in the analysis of teaching materials and the development of a new test instrument($\alpha$=0.81). According to the analysed results, the understanding levels for scales and relationships of communities, populations, ecosystem were high but those for individual concepts and differences were low. By the analysis of Korean High School EE book, ‘environmental science’, learning for some concepts(succession, material cycling, niche etc.) has pointed out as one of problems. Environmental educators must pay a careful attention to the concepts that showed high rates of incorrect answer and this work will contribute toward consolidating the basis of EE and help the accomplishment of the ultimate goals in EE.

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New constitutive models for non linear analysis of high strength fibrous reinforced concrete slabs

  • Yaseen, Ahmed Asaad;Abdul-Razzak, Ayad A.
    • Structural Engineering and Mechanics
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    • 제82권1호
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    • pp.121-131
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    • 2022
  • The main goal of this study is to prepare a program for analyzing High Strength Steel Fibrous Reinforced Concrete (HSSFRC) slabs and predict the response and strength of the slab instead of preparing a prototype and testing it in the laboratory. For this purpose, new equations are proposed to represent the material properties of High Strength Steel Fibrous Reinforced Concrete. The proposed equations obtained from performing regression analysis on many experimental results using statistical programs. The finite element method is adopted for non-linear analysis of the slabs. The eight-node "Serendipity element" (3 DoF) is chosen to represent the concrete. The layered approach is adopted for concrete elements and the steel reinforcement is represented by a smeared layer. The compression properties of the concrete are modeled by a work hardening plasticity approach and the yield condition is determined depending on the first two stress invariants. A tensile strength criterion is adopted in order to estimate the cracks propagation. many experimental results for testing slabs are compared with the numerical results of the present study and a good agreement is achieved regarding load-deflection curves and crack pattern. The response of the load deflection curve is slightly stiff at the beginning because the creep effect is not considered in this study and for assuming perfect bond between the steel reinforcement and the concrete, however, a great agreement is achieved between the ultimate load from the present study and experimental results. For the models of the tension stiffening and cracked shear modulus, the value of Bg and Bt (Where Bg and Bt are the curvature factor for the cracked shear modulus and tension stiffening models respectively) equal to 0.005 give good results compared with experimental result.

병원 간호현장에서의 억제대 사용실태에 관한 연구 (The Physical Restraint Use in Hospital Nursing Situation)

  • 김기숙;김진희;이선희;차혜경;신수정;지성애
    • 대한간호학회지
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    • 제30권1호
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    • pp.60-71
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    • 2000
  • This research is a field investigation to collect basic information about the safe and efficient use of physical restraint in hospitals and for the ultimate minimization of restraint use. The objects of this study were sixty-four patients. They were restrained physically. Add their 32 family members, 24 nurses of two university hospitals in Seoul were also involved in the study. From April 16, to May 27, 1999. Research data were collected throughout the observation and interview process. Also, the data was analyzed using frequencies and field study notes that were invented by researchers. Results of this study were as follows: 1. According to the sex and age distinction; male's restraint use was 75%, female's was 25% and pre-schoolage children 39.1%, middle age 26.5%, and senior citizens 20.3%. According to the disease distinction; neuro-system was 35.9%, respiratory system was 21.9%. In the Ward, 40.6% of ICU patients were restrained and 39.0% of pediatric ward children were also to restraint. 70.3% of patients were restrained under 5days, while 10.9% were restrained 10days. 2. Types of physical restraints were wrist restraint (45.21%), arm board (35.62%), leg restraint (8.22%), chest restraint (6.85%), elbow restraint (2.74%) and mitten restraint (1.37%). 3. The percentage was 3.5%, which was in 64 restrained out of 1828 hospitalized people. At 1st investigation, the ratio was 3.5%, the 2nd was 3.0% and the 3rd was 3.9%. 4. The reasons of using the physical restraint were 'to protect implements' (72.84%), 'to protect patients' (18.52%), 'to protect an operative site' (8.64%). 5. The result of the patients; family and nurses' response analysis was: 'It seems to be safe', 'It uses properly', 'It is convenient for relatives and nurses', 'It is helpful to treatment', 'Objective think it is not restraint' were 79.9%. 'It is discomfort and stuffy', 'The implement is ineffective' were 21.1%. However in interview of the patients who can do verbally communication, 6 of 7 was responded that 'It is stuffy and uncomfortable'. 6. When restraint is used, the main decision is usually made by the nurses 42.2% of the time. The statistics read as thus: nurses and the physician in charge 31.3%, nurses and family 12.5%, physician's order 7.8%, only family 6.2%. Although the record of restraint was only 15.6% so that only 10 cases out of all the 26 ICU patients restrained. This study shows that physical restraints which of infringe independent-right of patients, are used without using criterion, explaining the agreement. Also, subjective decision of physician, nurses, and family make the decision of using restraint. So development of practice manuals and rules for restraint implementation is urgent.

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기하 및 재료비선형을 갖는 적층평판의 p-Version 유한요소해석 (p-Version Finite Element Analysis of Composite Laminated Plates with Geometric and Material Nonlinearities)

  • 홍종현;박진환;우광성
    • 한국전산구조공학회논문집
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    • 제15권3호
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    • pp.491-499
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    • 2002
  • 직교이방성 적층평판해석을 위해 퇴화 쉘요소에 기초를 둔 p-version 유한요소법이 제안되었다. 이 모델의 비선형 정식화과정에서 기하비선형의 경우 von Karman의 대변형-소변형률 가정을 설명하기 위해 Total Lagrangian 방법이 채택되었으며, 재료비선형의 경우 Huber-Mises의 항복기준과 변형률경화 항복함수에 근거를 둔 Prandtl-Reuss 유동법칙이 사용되었다. 재료모델은 이방성을 표현하는 매개변수에 의해 이방겅재료를 고려할 수 있도록 하였다. 적층평판이론으로는 전단변형 효과를 고려할 수 있는 등가단출이론(ESL Theory)에 기초를 두었기 때문에 두 적층간 계면에서의 전단변형률은 연속이라는 조건을 갖게된다 적분형 르장드르 다항식이 형상함수로 사용되었으며 형상함수의 차수는 1차에서 10차까지 변화시킬 수 있다. 또한, Causs-Lobatto 수치적될법을 사용하기 때문에 기존의 가우스 적분점에서 계산되던 응력값은 이 적분법의 적분점이 절점에 위치하므로 절점에서 바로 응력값이 산출되도록 하였다 극한하중 수렴성, 비선형 효과, 소성역의 형상 등의 비교관점을 통해 p-version 유한요소 모델의 적정성을 보이고자 하였다.

경량 복합패널의 면내 전단 성능 평가 (Evaluation on In-plane Shear Strength of Lightweight Composite Panels)

  • 황문영;강수민;이병연;김성태
    • 한국산학기술학회논문지
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    • 제20권1호
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    • pp.9-20
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    • 2019
  • 국내에서의 지진과 같은 자연재해의 발생횟수가 증가하고 있다. 이에 따라 재해, 재난 환경에 적합한 임시거주공간 혹은 피난시설의 필요성이 증대되고 있다. 본 연구에서는 경량 복합패널을 이용하여 기존 피난시설과는 차별화된 구호주거를 제작하고자 하였다. 이를 위해 경량 복합패널에 대한 구조적 성능을 검증하고자 하였으며, 패널에 대한 성능 시험 방법 중 ASTM E72 기준에 따른 면내 전단 강도 실험을 진행하였다. 실험 결과, 각 실험체가 면내 하중을 받을 때의 최대하중을 알아내었다. 모든 실험체는 가력 부분의 패널이 찢어지면서 실험이 종료되었다. 실험체의 초기 강성은 계산을 통해 예측한 강성과 일치하였다. 하지만 패널의 특성인 국부적인 찌그러짐과 찢어짐으로 인해 강성저하와 최종파괴가 발생하였다. 개구부가 있는 실험체들은 개구부의 위치와 형태에 따라 기본 실험체와 강성과 강도에서 차이를 보였다. 또한 모든 실험 결과를 종합하여 패널이 받는 최대하중과 힘을 받는 면적이 비례한다는 것을 확인하였다. 이를 통해 실험체들의 극한전단응력을 계산하였으며, 평균 극한전단응력을 산정하였다. 경량 복합패널의 평균 극한전단응력은 $0.047N/mm^2$이며, 이 값을 통해 패널의 면적에 따른 허용하중을 합리적으로 예측할 수 있는 근거를 제시하였다.