• Title/Summary/Keyword: joint test

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Seismic performance of non-ductile detailing RC frames: An experimental investigation

  • Hidayat, Banu A.;Hu, Hsuan-Teh;Hsiao, Fu-Pei;Han, Ay Lie;Pita, Panapa;Haryanto, Yanuar
    • Earthquakes and Structures
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    • v.19 no.6
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    • pp.485-498
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    • 2020
  • Non-ductile detailing of Reinforced Concrete (RC) frames may lead to structural failure when the structure is subjected to earthquake response. These designs are generally encountered in older RC frames constructed prior to the introduction of the ductility aspect. The failure observed in the beam-column joints (BCJs) and accompanied by excessive column damage. This work examines the seismic performance and failure mode of non-ductile designed RC columns and exterior BCJs. The design was based on the actual building in Tainan City, Taiwan, that collapsed due to the 2016 Meinong earthquake. Hence, an experimental investigation using cyclic testing was performed on two columns and two BCJ specimens scaled down to 50%. The experiment resulted in a poor response in both specimens. Excessive cracks and their propagation due to the incursion of the lateral loads could be observed close to the top and bottom of the specimens. Joint shear failure appeared in the joints. The ductility of the member was below the desired value of 4. This is the minimum number required to survive an earthquake with a similar magnitude to that of El Centro. The evidence provides an understanding of the seismic failure of poorly detailed RC frame structures.

Sharing Economy: Generation Z's Intention Toward Online Fashion Rental in Vietnam

  • PHAM, Huong Trang;HOANG, Kim Thu;NGUYEN, Thi Thoa;DO, Phuong Huyen;MAR, Ma Tin Cho
    • The Journal of Asian Finance, Economics and Business
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    • v.8 no.3
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    • pp.997-1007
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    • 2021
  • The last decade has seen the emergence of the idea of "sharing economy" as people are more aware of environmental issues. Although clothing businesses applying the model of sharing consumption have emerged recently, less research effort has been invested in this topic, especially in investigating young consumers' intention. The purpose of this study is to investigate factors driving Generation Z consumers' behavioral intention toward online fashion rental. In this research, a conceptual framework is proposed based on the Theory of Planned Behavior and Technology Acceptance Model. To test the research model and hypotheses, a survey of 375 students and pupils was conducted in Vietnam. All the scales' reliability and validity were assessed through Cronbach's Alpha and confirmatory factor analysis. Structural equation modeling was used to assess the relationship among constructs. The study results showed that attitude toward behavior, subjective norm and perceived behavioral control were positive contributors to Gen Z's intention to use online fashion rental. Besides, the positive relationships between attitude and two other factors - perceived usefulness and perceived ease of use - were also highlighted. Moreover, the findings provided empirical evidence for supporting the positive impact of interpersonal influence, e-WOM, and influencer e-marketing on subjective norm.

The Effect of Lower Extremity Muscle Activity on Bridging Exercise and Combined Lifting pattern Bridging Exercise (교각운동과 들어올리기 패턴결합 교각운동이 하지 근 활성도에 미치는 영향)

  • Youn, Hye-Jin;Kim, Kyung-Hwan;Park, Sung-Hun;Yi, Min-Young
    • PNF and Movement
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    • v.10 no.4
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    • pp.49-55
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    • 2012
  • Purpose : The purpose of this study was to assess the effects of bridging exercise and combined lifting pattern bridging exercise on the lower extremity muscle activity. Methods : Twenty-five healthy adults volunteered to participate in this study. Subjects were required to complete following bridging exercises. Muscle activity was measured by QEMG-4 system(LXM 3204, Laxtha Korea). A paired t test was used to determine the influence of muscle activity for each exercise and descriptive statistics was used to characteristics of the subjects. Results : The biceps femoris, tibialis anterior, gastrocnemius of combined lifting pattern bridging exercise showed significance excepted vastus medialis(p<.05). In the case of men, biceps femoris showed significance in the combined lifting pattern bridging exercise(p<.05). In the case of women, biceps femoris and tibialis anterior showed significance in the combined lifting pattern bridging exercise(p<.05). Conclusion : The combined lifting pattern bridging exercise was more increased than bridging in lower extremity muscle activation. This result will be used for knee joint stabilizing exercises and biceps femoris strength training.

Validity and Reliability of an Oral Health Assessment Tool for Elderly in Long-Term Care Facilities (요양시설 노인을 위한 구강건강 평가 도구의 타당도와 신뢰도)

  • Kim, Na-Yeon;Bae, Hyun-Sook
    • Journal of Korean Dental Hygiene Science
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    • v.4 no.1
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    • pp.53-64
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    • 2021
  • Background: The elderly in long-term care facilities tend to have a diminished oral health status, with a high prevalence of dental caries and periodontal disease, as reduced cognitive function, joint mobility, and gait ability hinder the performance of oral hygiene. To improve the oral health of the elderly at long-term care facilities, it is necessary to have precise guidelines for oral health care and assessment; however, such guidelines are not readily available. Therefore, the present study aimed to develop an oral care assessment tool with verified reliability and validity. Methods: The participants in this study were 100 elderly patients at a care facilities and 10 clinical dental hygienists. Collected data were analyzed using the descriptive statistics, content validity index, and inter-rater reliability, as well as the analyses of intra-class correlation coefficient. Results: After a review of relevant literature, a preliminary questionnaire comprised of seven questions related to the evaluation of oral health was formed. After revising and supplementing the questions through a content validity test, a total of nine questions were selected. Conclusion: The novel assessment tool developed for the present study is anticipated to allow analyses of the level of problems related to oral health care before routine and professional care. Moreover, regular oral health status check-ups will enable the early diagnosis and treatment of diseases.

Stiffness model for "column face in bending" component in tensile zone of bolted joints to SHS/RHS column

  • Ye, Dongchen;Ke, Ke;Chen, Yiyi
    • Steel and Composite Structures
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    • v.38 no.6
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    • pp.637-656
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    • 2021
  • The component-based method is widely used to analyze the initial stiffness of joint in steel structures. In this study, an analytical component model for determining the column face stiffness of square or rectangular hollow section (SHS/RHS) subjected to tension was established, focusing on endplate connections. Equations for calculating the stiffness of the SHS/RHS column face in bending were derived through regression analysis using numerical results obtained from a finite element model database. Because the presence of bolt holes decreased the bending stiffness of the column face, this effect was calculated using a novel plate-spring-based model through numerical analysis. The developed component model was first applied to predict the bending stiffness of the SHS column face determined through tests. Furthermore, this model was incorporated into the component-based method with other effective components, e.g., bolts under tension, to determine the tensile stiffness of the T-stub connections, which connects the SHS column, and the initial rotational stiffness of the joints. A comparison between the model predictions, test data, and numerical results confirms that the proposed model shows satisfactory accuracy in evaluating the bending stiffness of SHS column faces.

Partially restrained beam-column weak-axis moment connections of low-rise steel structures

  • Lim, Woo-Young;Lee, Dongkeun;You, Young-Chan
    • Structural Engineering and Mechanics
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    • v.76 no.5
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    • pp.663-674
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    • 2020
  • In this study, partially restrained beam-column moment joints in the weak-axis direction were examined using three large-scale specimens subject to cyclic loading in order to assess the seismic resistance of the joints of low-rise steel structures and to propose joint details based on the test results. The influence of different number of bolts on the moment joints was thoroughly investigated. It was found that the flexural capacity of the joints in the direction of weak axis was highly dependent on the number of high-tension bolts. In addition, even though the flexural connections subjected to cyclic loading was perfectly designed in accordance with current design codes, severe failure mode such as block shear failure could occur at beam flange. Therefore, to prevent excessive deformation at bolt holes under cyclic loading conditions, the holes in beam flange need to have larger bearing capacity than the required tensile force. In particular, if the thickness of the connecting plate is larger than that of the beam flange, the bearing capacity of the flange should be checked for structural safety.

Effects of lumbar stabilization exercise according to correct verbal instructions in pain and muscle strengthening of low back pain patient

  • Ji, Sungha;Lee, Dongjin
    • Physical Therapy Rehabilitation Science
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    • v.10 no.1
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    • pp.69-75
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    • 2021
  • Objective: This study was aimed at investigating the effects of lumbar stabilization exercise according to correct verbal instructions in pain and muscle strengthening of the low back pain patients. Design: A randomized controlled trial. Methods: Twenty subjects with low back pain were selected. They were randomly assigned to one of two groups (10 in each group): namely the lumbar stabilization exercise and lumbar stabilization exercise according to the correct verbal instructions group. The lumbar stabilization exercise group performed lumbar stabilization exercises for 6 weeks (5 times a week). The lumbar stabilization exercise according to correct verbal instructions group performed lumbar stabilization exercise according to correct verbal instructions for 6 weeks (5 times a week). We measured pain, muscle power, proprioception, and body balance before and after exercise by using visual analog scale (VAS), digital handheld dynanometer, Joint repositioning error, time up and go test respectively. Results: We found statistically significant differences in pain, muscle power, proprioception, and body balance in lumbar stabilization exercise and lumbar stabilization exercise according to correct verbal instructions group, before and after (p<0.05). Conclusions: We confirmed the effect of lumbar stabilization exercise according to correct verbal instructions. Thus we thought these results could be used as basic data and reference for low back pain. But we need more study effect of correct verbal instructions on other exercises.

Shear Behaviour of Precast Concrete Modular Beam Using Connecting Plate (연결 플레이트를 사용한 프리캐스트 콘크리트 모듈러 보의 전단성능)

  • Cho, Chang Geun;Ro, Kyong Min;Lee, Young Hak
    • Journal of Korean Association for Spatial Structures
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    • v.21 no.4
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    • pp.65-72
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    • 2021
  • The Precast concrete(PC) modular structures are a method of assembling pre-fabricated unit modules in the construction site. The essential aim of modular structures is to introduce a connection method that can ensure splicing performance and effectively resist shear strength. This study proposed PC module using a connecting plate that can replace splice sleeves and shear keys used in the conventional PC modular structures. To evaluate the splicing performance and shear capacity of the proposed method, the shear test was conducted by fabricating one monolithic reinforced concrete(RC) beam and two PC modular beams with a shear span-to-depth ratio as variables. The experimental results showed that the shear capacity of the PC modular beam was about 89% compared to that of the RC beam, and showed a failure of the RC beam according to the shear span-to-depth ratio. Therefore, it was considered that the connecting plate effectively transferred the stress between each PC module through the joint and ensure integrity. In addition, the applicability of shear strength equation of ACI 318-19 and Zsutty's equation to PC modular beams were evaluated. Results demonstrated that the improved shear strength equations are needed to consider reduction of shear strength in PC modules.

Comparison of Effects of Non-surgical Continuous and Intermittent Traction on Pain, Balance and Physical Function in the Treatment of Knee Osteoarthritis

  • Lee, Dong-Kyu;Jeong, Jin-Gyu
    • The Journal of Korean Physical Therapy
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    • v.32 no.6
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    • pp.348-353
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    • 2020
  • Purpose: This study examined the comparison of effects of non-surgical continuous and intermittent traction on pain, balance and physical function in the treatment of knee osteoarthritis. Methods: A total of 30 knee osteoarthritis patients were recruited and randomized to a continuous traction group (n=10), an intermittent traction group (n=10), and a control group (n=10). The continuous traction group and intermittent traction group received a non-surgical continuous and intermittent knee joint traction workout five times a week, for 4 weeks. All subjects were assessed with the numeric rating scale (NRS), timed up and go test (TUGT), and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) before and after the 4-week treatment. Results: As a result of comparison within groups, the continuous traction group, intermittent traction group, and control group showed a significant difference for NRS, TUGT, and WOMAC after the experiment (p<0.05). According to the comparison of the three groups, the continuous traction group showed a more effectively significant difference than the intermittent traction group and the control group in the balance and physical functions before and after the experiment (p<0.05). Conclusion: This study showed that non-surgical continuous traction treatment was effective in improving pain, balance ability, and physical function in knee osteoarthritis patients.

Design and behavior of 160 m-tall post-tensioned precast concrete-steel hybrid wind turbine tower

  • Wu, Xiangguo;Zhang, Xuesen;Zhang, Qingtan;Zhang, Dong;Yang, Xiaojing;Qiu, Faqiang;Park, Suhyun;Kang, Thomas H.K.
    • Steel and Composite Structures
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    • v.44 no.3
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    • pp.407-421
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    • 2022
  • Prefabricated hybrid wind turbine towers (WTTs) are promising due to height increase. This study proposes the use of ultra-high performance concrete (UHPC) to develop a new type of WTT without the need to use reinforcement. It is demonstrated that the UHPC WTT structure without reinforcing bars could achieve performance similar to that of reinforced concrete WTTs. To simplify the design of WTT, a design approach for the calculation of stresses at the horizontal joints of a WTT is proposed. The stress distribution near the region of the horizontal joint of the WTT structure under normal operating conditions and different load actions is studied using the proposed approach, which is validated by the finite element method. A further parametric study shows that the degree of prestressing and the bending moment both significantly affect the principal stress. The shear-to-torsion ratio also shows a significant influence on the principal tensile stress.