• Title/Summary/Keyword: Ultimate Analysis

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Prediction on Ultimate Vertical and Horizontal Bearing Capacity of Steel Pipe Piles by Means of PAR (PAR에 의한 강관 말뚝의 극한 수직 및 수평 지지력 예측)

  • 최용규
    • Geotechnical Engineering
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    • v.13 no.4
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    • pp.13-24
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    • 1997
  • A predicting method for ultimate vertical and horizontal bearing capacity by means of PAR(Pile Analysis Routines) was suggested. Based on the static pile load test data, case studies by means of PAR were performed. Ultimate pile capacity predicted by PAR was within 15% error range of that determined by stairs pile load tests. Also, the results of static pile load test, statnamic tests and PDA data performed on pipe piles were compared and, by using PAR, ultimate pile capacity was determined. Distributions of atrial pile load could be predicted and load transfer analysis could be done approximately by those distributions.

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STRUCTURAL TEST AND ANALYSIS OF RC SLAB AFTER FIRE LOADING

  • Chung, Chul-Hun;Im, Cho Rong;Park, Jaegyun
    • Nuclear Engineering and Technology
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    • v.45 no.2
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    • pp.223-236
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    • 2013
  • In the present study the behavior of fire and the residual strength of fire-ignited RC slabs are investigated by experimental tests and numerical simulations. The fire tests of RC slabs were carried out in a furnace using the ISO 834 standard fire. The load capacity of the cooled RC slabs that were not loaded during the fire tests was evaluated by additional 3 point bending tests. The influence of the proportion of PP (polypropylene) fibers in the RC slabs on the structural behavior of the RC slabs after the fire loading was investigated. The results of the fire tests showed that the maximum temperature of concrete with PP fiber was lower than that of concrete without PP fiber. As the concrete was heated, the ultimate compressive strength decreased and the ultimate strain increased. The load-deflection relations of RC slabs after fire loading were compared by using existing stress-strain-temperature models. The comparison between the numerical analysis and the experimental tests showed that some numerical analyses were reliable and therefore, can be applied to evaluate the ultimate load of RC slabs after fire loading. The ultimate load capacity after cooling down the RC slabs without PP fiber showed a considerable reduction from that of the RC slabs with PP fiber.

Ultimate Shear Capacity of Prestressed Girder of Ultra High Performance Fiber Reinforced Concrete (초고강도 섬유보강 콘크리트 프리스트레스트 거더의 극한 전단력)

  • Han, Sang-Mook;Wu, Xiang-Guo
    • Journal of the Korean Society of Hazard Mitigation
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    • v.8 no.2
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    • pp.51-58
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    • 2008
  • This study is to investigate the ultimate shear load of prestressed girder made of Ultra High Performance Fiber Reinforced Concrete (UHPFRC). Nine girders were tested until failure in shear. An analytical model to predict the ultimate shear load was formulated based on the Two Bounds Theory. A fiber reinforcing model was constituted based on the random assumption of steel fiber uniform distribution. The predicted values were compared with the conventional predictions and the test results. The proposed equations for computing the ultimate shear strength can be used for the ultimate failure status analysis, which could also be utilized for numerical limit analysis of prestressed UHPFRC girder. The established fiber reinforcing theoretical model can also be a reference for micro-mechanics analysis of UHPFRC.

Changes in Mechanical Properties of Wood Due to 1 Year Outdoor Exposure

  • KIM, Gwang-Chul;KIM, Jun-Ho
    • Journal of the Korean Wood Science and Technology
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    • v.48 no.1
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    • pp.12-21
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    • 2020
  • For quantitative evaluation of wooden structures, the mechanical performance of members has undergone outdoor exposure tests. A year-long monitoring was conducted using an SPF species. Test groups were divided into twelve (each month) to measure the moisture content, density and ultimate load. Starting from May when moisture content of the test group was at the lowest, simple failure modes were observed more frequently during the first half of the experiment, whereas complex failure modes took over during the second half. Starting from June when moisture content of the test group was the highest, ultimate load decreased by 30% in the second half compared to the first half. A multiple regression analysis confirmed that moisture content of the test group was the variable with most effect on ultimate load of various outdoor variables, and an estimation equation of a simple regression analysis revealed that moisture content and ultimate load formed an inversely proportionate relationship. It is thought that correlational relationships of variables other than moisture content could be applied with the increase in added data amount by longer periods of outdoor exposure tests.

Numerical Parametric Analysis of the Ultimate Loading-Capacity of Channel Purlins with Screw-Fastened Sheeting

  • Zhang, Yingying;Xue, Jigang;Song, Xiaoguang;Zhang, Qilin
    • International journal of steel structures
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    • v.18 no.5
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    • pp.1801-1817
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    • 2018
  • This paper presents the numerical parametric analysis on the loading capacity of Channel purlins with screw-fastened sheeting, in which the effects of anti-sag bar and corrugated steel sheet on the ultimate capacity are studied. Results show that the setup of anti-sag bars can reduce the deformations and improve the ultimate capacity of C purlins. The traditional method of setting the anti-sag bars in the middle of the web is favorable. The changing of sheeting type, sheeting thickness and rib spacing has significant effects on the ultimate capacity of C purlins without anti-sag bars, compared with those with anti-sag bars. The proposed design formulas are relatively consistent with the calculations of EN 1993-1-3:2006, which is different from those of GB 50018-2002.

Development of Design Formula for Predicting Post-Buckling Behaviour and Ultimate Strength of Cylindrical Shell

  • Lee, Jung-Ho;Oh, Young-Cheol;Seo, Kwang-Cheol
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.23 no.3
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    • pp.313-319
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    • 2017
  • Cylindrical shells are often used in ship structures at deck plating with a camber, side shell plating at fore and aft parts, and bilge structure part. It has been believed that such curved shells can be modelled fundamentally by a part of a cylinder under axial compression. From the estimations with the usage of cylinder models, it is known that, in general, curvature increases the buckling strength of a curved shell subjected to axial compression, and that curvature is also expected to increase the ultimate strength. We conduct series of elasto-plastic large deflection analyses in order to clarify the fundamentals in buckling and plastic collapse behaviour of cylindrical shells under axial compression. From the numerical results, we derive design formula for predicting the ultimate strength of cylindrical shell, based on a series of the nonlinear finite element calculations for all edges, simply supporting plating, varying the slenderness ratio, curvature and aspect ratio, as well as the following design formulae for predicting the ultimate strength of cylindrical shell. From a number of analysis results, fitting curve can be developed to use parameter of slenderness ratio with implementation of the method of least squares. The accuracy of design formulae for evaluating ultimate strength has been confirmed by comparing the calculated results with the FE-analysis results and it has a good agreement to predict their ultimate strength.

A Quantitative Physical Parameter for Detection of Ultimate Failure State of Soil Using CEL Method in Finite Element Analysis (CEL 기법을 이용한 유한 요소 해석에서 지반의 극한 파괴 상태 감지를 위한 정량적 물리량 기준)

  • Kim, Seongmin;Lee, Ju-Hyung;Jung, Young-Hoon
    • Journal of the Korean Geotechnical Society
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    • v.34 no.12
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    • pp.59-69
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    • 2018
  • In order to use the limit equilibrium theory, it is necessary to find a slip line under the ultimate failure condition. The strength reduction method using the Lagrangian finite element method defines the ultimate failure state at a time when the numerical solution cannot converge within the certain number of the iteration. When the coupled Eulerian-Lagrangian (CEL) method is used, however, such definition is inappropriate because the numerical solution of the CEL method can converge even under the ultimate failure condition. In this study, an objective condition designating the ultimate failure state in the finite element analysis adopting the CEL method was proposed. In the problem of the bearing capacity of the undrained soft ground subjected to the strip footing loading, we found that the rate of the plastic dissipated energy is highly sensitive at the load of the theoretical limit of the ultimate failure state.

Change of Statical Behavior and Ultimate Capacity of Steel Cable-stayed Bridges after Cable Failure (케이블 단선 후 강사장교의 구조 및 극한 거동 변화)

  • Kim, Seung-Jun;Choi, Jun-Ho;Won, Deok-Hee;Han, Taek-Hee;Kang, Young-Jong
    • Journal of Korean Society of Steel Construction
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    • v.23 no.6
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    • pp.747-761
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    • 2011
  • This paper presents an investigation on the change in the statical behavior and the ultimate capacity of steel cable-stayed bridges after cable failure. Cable failure can occur due to fire, direct vehicle clash accidents, cable or anchorage fatigue, and so on. Moreover, the cable may be temporarily disconnected during cable replacement work. When cable failure occurs, the load, that was supported by the broken cable is first transferred to another cable. Then the structural state changes due to the interaction between the girder, mast, and cables. Moreover, it can be predicted that the ultimate capacity will decrease after cable failure, because of the loss of the support system. In this study, the analysis method is suggested to find the new equilibrium state after cable failure based on the theory of nonlinear finite element analysis. Moreover, the ultimate analysis method is also suggested to analyze the ultimate behavior of live loads after cable failure. For a more rational analysis, a three-step analysis procedure is suggested and used, which consisted of initial shape analysis, cable failure analysis, and live load analysis. Using this analysis method, an analytical study was performed to investigate the changes in the structural state and ultimate behavior of steel cable-stayed bridges.

Analysis and Design Programming of RC Beams Strengthened with Carbon Fiber Sheets (탄소섬유시트로 보강된 RC보의 해석 및 설계 프로그램 개발)

  • 김성도;김성수
    • Journal of the Korean Society for Railway
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    • v.7 no.4
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    • pp.319-325
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    • 2004
  • In this study, analysis and design programs of bending of RC beams strengthened with fiber sheets are developed by using Visual Basic Language. The program consists two groups, ultimate strength method and nonlinear flexural analysis method. Ultimate strength method regards concrete compressive stress as a rectangular stress block and do not consider tensile stress of concrete and load-deflection curves. On the other hand, nonlinear flexural analysis considers tensile stress of concrete, load-deflection curves, state of stress distribution and failure strain of strengthening material. Also, the analysis method used in this study regards nonlinear flexural stress as compressive stress of concrete. This program can be a good tool for determining the bending strength of strengthened RC beams and estimating the amount of fiber sheets for practical use.

PID Autotuning Algorithm with an Asymmetric Self-oscillation (비대칭 자기 진동에 대한 PID 자동동조 알고리듬)

  • Oh, Seung-Rohk
    • Journal of IKEEE
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    • v.6 no.2 s.11
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    • pp.128-135
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    • 2002
  • We use the saturation nonlinear feedback element to generate self-oscillation in order to find an ultimate gain and period of linear plant. The use of saturation nonlinear feedback element can improve accuracy of an ultimate gain and period of unknown linear plant. An ultimate gain and period of linear plant can be used to tune a PID controller parameters. It is possible that an asymmetric oscillation can be occurred under the special circumstances such as with static load disturbance. We analyze an asymmetric self-oscillation. As the results of an analysis, we propose a method to find an ultimate gain and period of linear Plant under the asymmetric self-oscillation.

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