• Title/Summary/Keyword: Stress-Strength Analysis

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Experiment and Strength Analysis of High-Strength RC Columns (고강도 철근 콘크리트 기둥의 실험 및 강도해석)

  • Son, Hyeok-Soo;Kim, Jun-Beom;Lee, Jae-Hoon
    • Magazine of the Korea Concrete Institute
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    • v.11 no.1
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    • pp.149-160
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    • 1999
  • This paper is a part of a research aimed at the verification of basic design rules of high-strength concrete columns. A total of 32 column specimens were tested to investigate structural behavior and strength of eccentrically loaded reinforced concrete tied columns. Main variables included in this test program were concrete compressive strength. steel amount, eccentricity, and slenderness ratio. The concrete compressive strength varied from 356 kg/$cm^2$ to 951 kg/$cm^2$ and the longitudinal steel ratios were between 1.13 % and 5.51 %. Test results of column sectional strength are compared with the results of analyses by ACI rectangular stress block, trapezoidal stress block, and modified rectangular stress block. Axial force-moment-curvature analysis is also performed for predicting axial load-moment strength and compared with the test results. The ACI rectangular stress block provides over-estimated column strengths for the lightly reinforced high strength column specimens. The calculated strengths by moment-curvature analyses are highly affected by $k_3$ values of the concrete stress-strain curve. Observed failure mode. concrete ultimate strain, and stress block parameters are discussed.

Analysis and Environment on Bond Characteristic of High-Strength Steel RC Members (고장력 철근을 사용한 RC부재의 부착특성에 관한 해석 및 실험)

  • 곽성태;윤영수;송영철;우상균
    • Proceedings of the Korea Concrete Institute Conference
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    • 2001.05a
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    • pp.443-448
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    • 2001
  • This paper presents a bond characteristics of high strength steel reinforced concrete members. High strength steel is what yield strength is higher than that of normal strength steel. So, the amount of flexural steel needed in R.C. members can be decreased. In result, it is expected that the workability and structure quality can improve and man power can minimize. For this purpose, specimens were made and tested with experimental parameters, such as concrete strength, steel diameter and yield strength. The result showed that under same tensile force of steel, in case of substituting normal strength steel with high strength steel, maximum bond stress increased and development length didn't almost change. In addition, the governing equation of bond and bond stress verse slip relationship were derived and compared with test values such as maximum bond stress, slip and bond stiffness.

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Strength criterion of plain recycled aggregate concrete under biaxial compression

  • He, Zhen-Jun;Liu, Gan-Wen;Cao, Wan-Lin;Zhou, Chang-Yang;Jia-Xing, Zhang
    • Computers and Concrete
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    • v.16 no.2
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    • pp.209-222
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    • 2015
  • This paper presents results of biaxial compressive tests and strength criterion on two replacement percentages of recycled coarse aggregate (RPRCA) by mass for plain structural recycled aggregate concrete (RAC) at all kinds of stress ratios. The failure mode characteristic of specimens and the direction of the cracks were observed and described. The two principally static strengths in the corresponding stress state were measured. The influence of the stress ratios on the biaxial strengths of RAC was also analyzed. The experimental results showed that the ratios of the biaxial compressive strength ${\sigma}_{3f}$ to the corresponding uniaxial compressive strength $f_c$ for the two RAC are higher than that of the conventional concrete (CC), and dependent on the replacement percentages of recycled coarse aggregate, stress states and stress ratios; however, the differences of tensile-compressive ratios for the two RAC and CC are smaller. On this basis, a new failure criterion with the stress ratios is proposed for plain RAC under biaxial compressive stress states. It provides the experimental and theoretical foundations for strength analysis of RAC structures subject to complex loads.

Stress Analysis and Design Improvement to Prevent Failure of the Damping Hinges of Built-in Refrigerators (빌트인 냉장고 댐핑힌지의 응력해석 및 파손방지를 위한 설계개선)

  • Lee, Boo-Youn
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.19 no.2
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    • pp.81-88
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    • 2020
  • The damping hinge of a built-in refrigerator was examined in terms of its stress and fatigue life. Analysis of the initial design showed that stress concentration occurred at the concave surface of the hinge lever, which was broken during the door opening-and-closing endurance test of the prototype. The maximum von Mises stress at this location exceeded the yield strength. In addition, Goodman fatigue analysis of the initial design showed that the fatigue life at this location was consistent with the failure observed during the endurance test. Based on these results, an improved design for the damping hinge was derived. Analysis of this improved design showed that the stress concentration in the hinge lever of the initial design was eliminated. In this case, the maximum stress occurred at the position where the hinge lever was in contact with the door stopping pin, and the maximum von Mises stress was smaller than the yield strength. Goodman fatigue analysis of the improved design indicated that the fatigue life of the entire damping hinge was infinite. It was therefore concluded that the improved design does not suffer from fatigue damage during the endurance test.

Stress interactions between two asymmetric noncircular tunnels

  • La, You-Sung;Kim, Bumjoo;Jang, Yeon-Soo;Choi, Won-Hyuk
    • Geomechanics and Engineering
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    • v.15 no.3
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    • pp.869-877
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    • 2018
  • The continually growing demand for underground space in dense urban cities is also driving the demand for underground highways. Building the underground highway tunnel, however, can involve complex design and construction considerations, particularly when there exists divergence or convergence in the tunnel. In this study, interaction between two asymmetric noncircular tunnels-that is, a larger main tunnel and a smaller tunnel diverging from the main tunnel, was investigated by examining the distributions of the principal stresses and the strength/stress ratio for varying geometric conditions between the two tunnels depending on diverging conditions using both numerical analysis and scale model test. The results of numerical analysis indicated that for the $0^{\circ}$, $30^{\circ}$, $60^{\circ}$ diverging directions, the major principal stress showed an initial gradual decrease and then a little steeper increase with the increased distance from the left main tunnel, except for $90^{\circ}$ where a continuous drop occurred, whereas the minor principal stress exhibited an opposite trend with the major principal stresses. The strength/stress ratio showed generally a bell-shaped but little skewed to left distribution over the distance increased from the left larger tunnel, similarly to the variation of the minor principal stress. For the inter-tunnel distance less than 0.5D, the lowest strength/stress ratio values were shown to be below 1.0 for all diverging directions ($0^{\circ}$, $30^{\circ}$, $60^{\circ}$ and $90^{\circ}$). The failure patterns observed from the model test were found to be reasonably consistent with the results of numerical analysis.

Effects of Member Sizes on ACI Rectangular Stress Block and Actual Stress Distribution (ACI 직사각형 응력블럭과 실제 응력분포에 부재의 크기가 미치는 영향)

  • 이성태;김장호;김진근
    • Proceedings of the Korea Concrete Institute Conference
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    • 2001.05a
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    • pp.909-914
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    • 2001
  • It is important to consider an effect of concrete member sizes when estimating the ACI rectangular stress block of a reinforced concrete flexural member. However, the experimental data and analytical analyses are still not available for a proper evaluation. For all types of loading conditions, the trend is that the size of an ACI rectangular stress block tends to change when the member sizes change. In this paper, the size variations of strength coefficients for ACI rectangular stress block and actual stress distribution have been studied. Results of a series of C-shaped specimens subjected to axial compressive load and bending moment were adopted from references 1 and 2. The analysis results show that the effect of specimen sizes on strength coefficients for ACI rectangular stress block and actual stress distribution of concrete member was apparent. Thus, the results suggest that the current strength criteria based design practice should be reviewed.

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Creep characteristics and instability analysis of concrete specimens with horizontal holes

  • Xin, Yajun;Hao, Haichun;Lv, Xin;Ji, Hongying
    • Computers and Concrete
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    • v.22 no.6
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    • pp.563-572
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    • 2018
  • Uniaxial compressive strength test and uniaxial compression creep one were produced on four groups of twelve concrete specimens with different hole number by RLW-2000 rock triaxial rheology test system. The relationships between horizontal holes and instantaneous failure stress, the strain, and creep failure stress, the strain, and the relationships between stress level and instantaneous strain, creep strain were studied, and the relationship between horizontal holes and failure mode was determined. The results showed that: with horizontal hole number increasing, compressive strength of the specimens decreased whereas its peak strain increased, while both creep failure strength and its peak strain decreased. The relationships between horizontal holes and compressive strength of the specimens, the peak strain, were represented in quadratic polynomial, the relationships between horizontal holes and creep failure strength, the peak strain were represented in both linear and quadratic polynomial, respectively. Instantaneous strain decreased with stress level increasing, and the more holes in the blocks the less the damping of instantaneous strain were recorded. In the failure stress level, instantaneous strain reversally increased, creep strain showed three stages: decreasing, increasing, and sharp increasing; in same stress level, the less holes the less creep strain rate was recorded. The compressive-shear failure was produced along specimen diagonal line where the master surface of creep failure occurred, the more holes in a block, the higher chances of specimen failure and the more obvious master surface were.

Distribution of the Equivalent Rectangular Stress Block for High-Strength Polymer Concrete Beams (고강도 폴리머 콘크리트보의 등가직사각형 응력분포)

  • 김관호;연규석;김남길;조규우
    • Proceedings of the Korea Concrete Institute Conference
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    • 2001.05a
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    • pp.915-920
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    • 2001
  • This study was conducted to analysis the distribution of the rectangular stress block for high-strength polymer concrete beam. C-shaped specimens were produced and tested to compute parameters of the rectangular stress block. They were $\kappa_{1}$ = 0.73, $\kappa_{3}$ = 0.94 and $\gamma$= 0.845, respectively. Experimental value of flexural strength of beam was same to be compared with theoretical value. But there is desirable to need many experimental data in order to exact design of polymer concrete structure.

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Strength Design Evaluation of the Multi-range Transmission (다단 변속기의 강도설계 검증)

  • Kong, M.G.;Song, C.K.;Kim, Y.D.
    • Journal of Power System Engineering
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    • v.15 no.3
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    • pp.12-17
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    • 2011
  • Gears are useful for power transmission due to excellent power transmission performance, low cost, and compactness. In addition, gears have constant speed ratio, compact structure, and excellent efficiency. In order to transmit higher power, the new multi-range transmission requires gears which have greater strength than the existing transmission. This study evaluates stability and durability through gear analysis of the multi-range transmission in commercial vehicles using ROMAX-DESIGNER program. Also, strength design evaluation is carried out by the analysis results which are compared with gear strength theory of AGMA standard. Bending stress and contact stress on gears are lower than their allowable stresses. Therefore, we can evaluate the safety of the gear strength design in multi-range transmission.

Analysis of Thermal Stress and Fatigue Life in the Steel Shell of a Cupola Furnace (큐폴라 용해로 철피의 열응력 및 피로수명 해석)

  • Yang, Young-Soo;Bae, Kang-Yul
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.19 no.2
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    • pp.47-54
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    • 2020
  • Themo-mechanical analysis was carried out using the finite element method for the steel shell of a cupola furnace. When the outer surface of the shell was cooled with water to within the temperature range of 35-80 ℃ during operation of the cupola, the inner surface of the shell was expected to exhibit a temperature of 65-248 ℃ based on heat transfer analysis. The shell was also expected to have an equivalent stress range of 100-280 MPa in the outer surface over the temperature range examined. Upon cooling the shell to obtain an outer surface temperature <80 ℃, the maximum equivalent stress of the shell did not exceed the yield strength. Although the temperature of the outer surface varied between 35 and 80 ℃ periodically due to the cooling control problem, the fatigue stress at the outer surface of the shell was calculated to be within the fatigue strength. During a non-operational period to examine the system between furnace operations, the thermal stress presented in the shell was sufficiently low to reach the desired yield strength and fatigue limit.