• Title/Summary/Keyword: allowable compressive stress

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An Experimental Study on Allowable Compressive Stress at Prestress Transfer in Pre-Tensioned Concrete Members (프리텐션된 콘크리트 부재의 프리스트레스 도입시 허용압축응력에 관한 실험적 연구)

  • Lee, Jeong Yeon;Lee, Deuck Hang;Kim, Kang Su;Park, Min Kook;Yoon, Sang Chun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.16 no.4
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    • pp.9-17
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    • 2012
  • In the previous research, allowable compressive stress was analyzed based on strength theory, in which primary effect factors on the allowable compressive stress, such as eccentricity ratio, section type, section size, prestress and self-weight moment, were considered. As its results, allowable compressive stress equations were proposed. As a series of the previous research, this paper presents an experimental study on the prestress at transfer of pre-tensioned members with different eccentricity ratios. The results shows that ACI318-08 and EC2-02 are unconservative for the members under low eccentricity ratios, and they are conservative for the members under high eccentricity ratios. Compared to the code provisions, the results indicates that the proposed equation reasonably well evaluates the allowable compressive stresses for those with different eccentricity ratios.

Allowable Stress Calculation of Domestic Japanese Larch Small Diameter Lumbers (국내산 낙엽송 소경각재의 허용응력 산출)

  • Kim, Yun-Hui;Shin, Il-Joong;Yang, Jung-Mo;Jang, Sang-Sik
    • Journal of the Korea Furniture Society
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    • v.23 no.2
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    • pp.214-221
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    • 2012
  • Sustainable energy consumption and increasing $CO_2$ emissions stimulate Eco-friendly industry. Wood has positive various properties as alternative energy such as solar, wind and water. Wood provide lumber, pallet, paper, pulp and fuel through production process. Even Korea republic has 63.7% of forest rates, weather condition makes low forestry production capacity. For utilization of domestic small diameter log needs study mechanical properties. In this study, various properties tested on domestic Japanese Larch small diameter lumbers and make mechanical properties table for allowable stress calculation. Result of compressive test, allowable compressive stress is 13 MPa. Allowable bending stress is 12 MPa.

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Allowable Compressive Stress of Pre-Tensioned Members with Tee or Inverted Tee Sections at Transfer (T형 및 역T형 단면을 가지는 프리텐션부재의 프리스트레스 도입시 허용 압축응력)

  • Lee, Deuck-Hang;Lee, Jeong-Yeon;Lim, Joo-Hyuk;Kim, Kang-Su
    • Journal of the Korea Concrete Institute
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    • v.23 no.3
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    • pp.353-364
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    • 2011
  • In a previous research performed by the authors, the allowable compressive stress coefficient (K) in pretensioned members with rectangular section at transfer was proposed based on strength design theory. In this study, a subsequent research of an enormous analysis was performed to determine the K factor for Tee and inverted Tee section members, considering the effect of section height (h), section type, amount of tendons ($A_{ps}$), and eccentricity ratio (e/h). Based on the analysis results, the allowable compressive stress coefficients (K) for Tee and inverted Tee section members at transfer were derived, which limit the maximum allowable stresses as 80% and 70% of the compressive strengths at the time of release for Tee section and inverted Tee section, respectively. And these were larger than the allowable stresses specified in domestic and other international codes. In order to verify the proposed equations, they were compared to the test results available in literature and other codes, which showed that the allowable stresses in domestic and international codes are unconservative for the cases with low eccentricity ratios while conservative for those with high eccentricity ratios. The proposed equations, however, estimate the allowable stresses of the Tee and inverted Tee section members reasonably close to test results.

FEM Analysis of Effect of Shot Peening for Stress Corrosion Cracking at Welded Part (용접부 응력부식균열 방지를 위한 쇼트피닝 효과의 유한요소 해석)

  • NAM KI-Woo;AHN SEOK-WHAN
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2004.11a
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    • pp.239-241
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    • 2004
  • Stress intensity factor of semi-circular crack front was calculated by FEM, and also allowable crack size which doesn‘t break out the fracture by SCC in residual stress field of STS materials. Allowable crack size was increased with compressive residual stress provided by shot peening on material surface, and with magnitude of compressive residual stress for depth direction.

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A Strength Analysis of Gear Train for Hydro-Mechanical Continuously Variable Transmission

  • Bae, Myung Ho;Bae, Tae Yeol;Yoo, Young Rak
    • International Journal of Advanced Culture Technology
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    • v.6 no.3
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    • pp.163-172
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    • 2018
  • The power train of hydro-mechanical continuously variable transmission(HMCVT) for the middle class forklift makes use of an hydro-static unit, hydraulic multi-wet disc brake & clutches and complex helical & planetary gears. The complex helical & planetary gears are a very important part of the transmission because of strength problems. The helical & planetary gears belong to the very important part of the HMCVT's power train where strength problems are the main concerns including the gear bending stress, the gear compressive stress and scoring failures. The present study, calculates specifications of the complex helical & planetary gear train and analyzes the gear bending and compressive stresses of the gears. It is necessary to analyze gear bending and compressive stresses confidently for an optimal design of the complex helical & planetary gears in respect of cost and reliability. This paper not only analyzes actual gear bending and compressive stresses of complex helical & planetary gears using Lewes & Hertz equation, but also verifies the calculated specifications of the complex helical & planetary gears by evaluating the results with the data of allowable bending and compressive stress from the Stress - No. of cycles curves of gears. In addition, this paper explains actual gear scoring and evaluates the possibility of scoring failure of complex helical & planetary gear train of hydro-mechanical continuously variable transmission for the forklift.

The Stress Analysis of Planetary Gear System of Mixer Reducer for Concrete Mixer Truck

  • Bae, Myung Ho;Bae, Tae Yeol;Cho, Yon Sang;Son, Ho Yeon;Kim, Dang Ju
    • Journal of Drive and Control
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    • v.12 no.4
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    • pp.77-81
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    • 2015
  • In general, the gears of mixer reducer for concrete mixer truck make use of the differential type planetary gear system to rotate mixer drum smoothly on the initial conditions. The planetary gear system is very important part of mixer reducer for concrete mixer truck because of strength problem. In the present study, calculating the gear specifications and analyzing the gear bending & compressive stresses of the differential planetary gear system for mixer reducer are necessary to analyze gear bending and compressive stresses confidently, for optimal design of the planetary gear system in respect to cost and reliability. As a result, analyzing actual gear bending and compressive stresses of the planetary gear system using Lewes & Hertz equation and verifying the calculated specifications of the planetary gear system, evaluate the results with the data of allowable bending and compressive stress from the Stress-No. of cycles curves of gears.

Study of the Distribution Properties and LRFD Code Conversion in Japanese Larch

  • Park, Chun-Young;Pang, Sung-Jun;Park, Ju-Sang;Kim, Kwang-Mo;Park, Mun-Jae;Lee, Jun-Jae
    • Journal of the Korean Wood Science and Technology
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    • v.38 no.2
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    • pp.94-100
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    • 2010
  • This study was performed to develop an LRFD (Load Resistance Factored Design) Code for Domestic Larch. To accomplish his, we evaluated bending, compression, tension and shear strength. The results of the strength evaluation were utilized to verify the distribution and code conversion. For bending, tension and compressive strength, the Weibull distribution was well-fitted, but for shear strength we observed a normal distribution. For evaluating the bending and compressive strength, a full-sized specimen was used. A small clear specimen was used to test tension and shear strength. Compressive strength in particular was found to be affected by tight knots, although there was little difference between grades. In the code conversion, the design value of the LRFD was larger than the existing allowable stress value in the Korean Building Code. However, the allowable stress in this study was about two times higher than the value listed in the Korean Building Code. This result induced the difference between the soft and hard conversions. For greater reliability, the accumulation of additional data is necessary and further studies should be performed

Compression strength performance of multi-layer glued columns by using square lumbers produced from domestic small diameter logs (국산 간벌 소경재를 이용한 다중접착접합 기둥부재의 압축강도성능)

  • Shin, Il-Joong;Kim, Yun-Hui;Jang, Sang-Sik
    • Korean Journal of Agricultural Science
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    • v.38 no.3
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    • pp.533-540
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    • 2011
  • This study is to develop a mulit-layer glued columns for construction of Korean-style houses by using domestic small diameter logs. Dried small square lumber glued each other to develop a multi-layer glued columns and evaluated its performance of strength. Then, predicted the design load of multi-layer glued columns and make a comparison between actual load and design load of multi-layer glued columns. In the results, allowable load by allowable stress of multi-layer glued columns was measured one-third of actual columns load and prediction load was measured less than 10~30% of the actual load. Therefore, muilt-layer glued member has a standard allowable stress of compressive of 13 MPa (Larix leptolepis) and 19 MPa (Chamaecyparis obtusa) when used as columns. Also, using compression strength of small diameter square logs could calculate maximum loads of multi-layer glued member as column.

The Strength Analysis of Gears on Hydro-Mechanical Continuously Variable Transmission for Forklift (지게차용 기계유압식 무단변속기의 기어류에 대한 강도해석)

  • Bae, Myung Ho;Bae, Tae Yeol;Choi, Sung Kwang
    • Journal of Drive and Control
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    • v.13 no.4
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    • pp.45-51
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    • 2016
  • The power train of a hydro-mechanical, continuously variable transmission for forklifts makes use of hydro-static units, hydraulic multi-wet disc brakes & clutches, and complex helical & planetary gears. The complex helical & planetary gears are very important parts of the transmission because of a strength problem. In the present study, we calculated the specifications of the complex helical & planetary gear train, and analyzed the gear bending and compressive stresses of the gears. It is necessary to analyze the gear bending and compressive stresses thoroughly for optimal design of the complex helical & planetary gears with respect to cost and reliability. In this paper, we analyze the actual gear bending and compressive stresses of complex helical & planetary gears using the Lewes & Hertz equation, and we also verify the calculated specifications of the complex helical & planetary gears by evaluating the results of the data of allowable bending and compressive stress using the Stress vrs Number of Cycles curves of gears.

Comparison of Allowable Axial Stress Provisions of Cylindrical Liquid Storage Tanks under Seismic Excitation (지진 하중을 받는 원통형 플랜트 탱크 구조물의 축방향 허용압축응력 설계기준 비교 연구)

  • Oh, Chang Kook;Lee, So Ri;Park, Jang Ho;Bae, Doobyong
    • Journal of Korean Society of Steel Construction
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    • v.28 no.4
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    • pp.293-301
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    • 2016
  • Stability of cylindrical liquid storage tanks under seismic excitation could prevent catastrophic disaster of human life and economic loss. Domestic provisions on allowable compressive stress in tank walls to prohibit buckling failure are either incomplete or inconsistent, so foreign specifications such as API 650, BS EN 1998-4:2006 or New Zealand Standards are employed in stability design. In this study, response spectrum analyses are performed for plant tanks having different ratios of height to diameter or diameter to thickness to calculate hydrodynamic pressure on tank walls. Then nonlinear buckling analyses are conducted to estimate magnitude of buckling stress. By comparing analysis results with those from foreign design specifications, appropriate domestic design provisions are suggested.