• Title/Summary/Keyword: 국부 단면손상

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Tensile Strength Change of Circular Structural member with Artificial Sectional Surface Damage (인위적 표면 단면손상 수준에 따른 원형 부재의 인장성능 변화)

  • Ha, Min-Gyun;Kwon, Tae-Yun;Lee, Won-Hong;Ahn, Jin-Hee
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.25 no.3
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    • pp.100-109
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    • 2021
  • This study was examined the tensile strength change of a circular tubular member with artificial sectional damage on its surface to consider surface sectional damage by corrosion. The tensile strength tests were conducted using circular tubular specimens with artificial sectional damage considering sectional damaged height and width on its surface according to the corrosion level. From the tensile strength test results, it is confirmed that tensile strength of the circular tubular specimens was affected by the damaged circumference (damaged width), not damaged length (damaged height) and their tensile failures were appeared at the minimum section of the artificial sectional damage part. Nonlinear finite-element analyses were conducted considering equivalent sectional damage effect on sectional damaged part in tensile specimens to examine the change in the tensile strength of tubular specimens with artificial sectional damage since it is difficult to estimate the sectional damaged surface condition of the specimens clearly. From the nonlinear finite element analysis results for the tensile test specimens, tensile strengths of test specimens with irregular sectional damaged surface were relatively evaluated to be highly decreased than these of FE analysis model with equivalent sectional damage. Therefore, residual tensile strengths of tensile members with irregular sectional damage as local corrosion can be evaluated and predicted using correlation coefficient between tensile test results and FE analysis results with equivalent sectional damage.

Local Fault Detection Technique for Steel Cable using Multi-Channel Magnetic Flux Leakage Sensor (다채널 자속누설 센서를 이용한 강케이블의 국부 단면손상 검색)

  • Park, Seunghee;Kim, Ju-Won;Lee, Changgil;Lee, Jongjae;Gil, Heung-Bae
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.25 no.4
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    • pp.287-292
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    • 2012
  • In this study, Multi-Channel Magnetic Flux Leakage(MFL) sensor - based inspection system was applied to monitor the condition of cables. This inspection system measures magnetic flux to detect the local faults(LF) of steel cable. To verify the feasibility of the proposed damage detection technique, an 8-channel MFL sensor head prototype was designed and fabricated. A steel cable bunch specimen with several types of damage was fabricated and scanned by the MFL sensor head to measure the magnetic flux density of the specimen. To interpret the condition of the steel cable, magnetic flux signals were used to determine the locations of the flaws and the level of damage. Measured signals from the damaged specimen were compared with thresholds set for objective decision making. In addition, the magnetic flux density values measured from every channel were summed to focus on the detection of axial location. And, sum of flux density were displayed with threshold. Finally, the results were compared with information on actual inflicted damages to confirm the accuracy and effectiveness of the proposed cable monitoring method.

Shear Buckling Strength and Behaviors of Steel Plate Girder with Asymmetrical Shear Resistant Web Panel by Local Corrosion (국부 부식손상에 의하여 비대칭 전단저항 복부단면을 가진 강거더의 전단강도 및 거동평가)

  • Lee, Myoung Jin;Ahn, Jin Hee;Kim, In Tae
    • Journal of Korean Society of Steel Construction
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    • v.26 no.2
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    • pp.105-118
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    • 2014
  • The number of the deteriorated bridge has been sharply increased due to the increase in the bridge service period in Korea. Local corrosion problem of structural member can be occurred according to atmospheric corrosion environments based on the installation location of steel bridges. Especially, in case of the plate girder bridge, corrosion damage is concentrated on the web panel and stiffener at girder end. An asymmetrical shear resistant web section in the plate girder bridge can be caused from the local corrosion of the web panel, because local corrosion is not symmetrically occurred to the bridge. In this study, therefore, the shear buckling strength and behavior of a plate girder with asymmetrically corroded web panel was numerically evaluated using FE analysis, which was considering an aspect ratio and corrosion damage level of web panel. The shear buckling strength reduction of an asymmetrical shear resistant web panel was compared and evaluated according to corroded volume ratio for a web panel and for diagonal tension field of a web panel.

Evaluation of Compressive Strengths of Tubular Steel Members According to Corrosion Damage and Shape (원형 강관의 국부 부식손상 수준 및 손상형태에 따른 압축강도 성능평가)

  • Ahn, Jin Hee;Nam, Dong Kyun;Lee, Won Hong;Huh, Jungwon;Kim, In Tae
    • Journal of Korean Society of Steel Construction
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    • v.28 no.4
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    • pp.213-222
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    • 2016
  • For a steel structure with long service period, structural performance can be changed or decreased by corrosion damage occurred under severe corrosion environment condition. In this study, to examine compressive strength and behavior of circular steel member depending on corrosion damage, compressive loading tests were conducted using circular steel member with artificial corrosion damage which was applied by mechanical process and hand drill. From test results, local corrosion area and pattern is related to their structural performance. Their lcoal bucklings were occurred near artificially sectional damaged part. Reduction in compressive strength of circular steel member was also suggested according to their corroded part and damage.

Elasto-Magnetic Sensor-Based Local Cross-Sectional Damage Detection for Steel Cables (Elasto-Magnetic 센서를 이용한 강재 케이블 국부 단면 감소 손상 탐지)

  • Kim, Ju-Won;Nam, Min-Jun;Park, Seung-Hee;Lee, Jong-Jae
    • Journal of the Korean Society for Nondestructive Testing
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    • v.31 no.4
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    • pp.360-366
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    • 2011
  • The Elasto-magnetic sensor is applied to detect the local cross-sectional loss of steel cables in this study while it was originally developed for measuring the tensile force in the previous works. To verify the feasibility of the proposed damage detection technique, steel bars which have 4-different diameters were fabricated and the output voltage value was measured at each diameter by the E/M sensor. Optimal input voltage and working point are chosen so that the linearity and resolution of results can ensure through repeated experiments, and then the E/M sensor was measured the output voltage values at the damage points of steel bar specimen that was applied the 4 types of damage condition based on the selected optimal experimental condition. This proposed approach can be an effective tool for steel cable health monitoring.

Magnetic Flux Leakage Method based Local Fault Detection for Inspection of Wire Rope (승강기 와이어로프 진단을 위한 누설자속기법 기반 국부손상 진단)

  • Kim, Ju-Won;Park, Ju-Young;Park, Seunghee
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.28 no.4
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    • pp.417-423
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    • 2015
  • In this study, Magnetic Flux Leakage(MFL)-based inspection system was applied to detect the local fault of wire rope. To verify the feasibility of the proposed damage detection technique, an 4-channel MFL sensor head prototype was designed and fabricated. A wire rope with several types of cross-sectional damages were fabricated and scanned by the MFL sensor head to measure the magnetic flux density of the wire rope specimen. To interpret the condition of the wire rope, magnetic flux signals were used to determine the locations of the flaws. To improve the resolution of signal, the instantaneous variation value of magnetic flux was utilized. Measured signals from the damaged specimen were compared with thresholds set for objective decision making. Finally, the results were compared with information on actual inflicted damages to confirm the accuracy and effectiveness of the proposed cable monitoring method.

Evaluation on Bearing Capacity of End Girder Member with Local Corrosion (지점부 부재의 부식손상에 따른 강거더 단부 지압강도 평가)

  • Ahn, Jin Hee;Lee, Won Hong;Kim, In Tae;Jeong, Young Soo
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.21 no.5
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    • pp.74-82
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    • 2017
  • Localized corrosions damages in their structural sections can be occurred affected by installed environment conditions with high temperature as near the coastline and humidity or their poor maintenance situation. In bearing supports of steel bridges, especially, lower web and vertical stiffener in end girder support can be easily corroded because of relatively higher humidity due to the narrow space in the end of girder and the wetted accumulated sediments affected by rain water or antifreezing admixture leaked from expansion joint. It can be related to change in their structural performance. In this study, thus, bearing strength test specimens were fabricated considering corrosion damage in the web and vertical stiffeners and the change in their bearing strengths were experimentally evaluated. From the test results, localized corrosion damage of structural members in the end girder affected the bearing strength of end girder support, especially, localized corrosion damage of the vertical stiffener relatively highly affected their bearing strengths.

A Study on the Ultimate Strength and Behavior of Circular Section Subjected to Cross-Sectional Distortion (뒤틀림변형을 받는 관형단면의 극한강도 및 거동에 관한 연구)

  • Kim, Woo Bum
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.14 no.1
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    • pp.83-91
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    • 1994
  • An efficient method was developed to determine the ultimate strength for the segment subjected to cross-sectional distortion. Cumulative data based on the finite element analysis were used to perform the multi-regression analysis. A moment-thrust-curvature relationship of short segment was obtained with mathematical forms in the nonlinear range. The extensive parametric study was performed to generate the ultimate strength for the various segments. The result was compared with the experimental result which was not included in the database. The proposed method gives an essential tool for the nonlinear analysis of beam-column.

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Stress History Evaluation for Truss Bridge with Local Damages by Using Global-Local Model Combination (전체해석과 국부해석 조합법을 이용한 국부결함이 있는 트러스교 응력이력해석)

  • Kim, Hyo-Jin;Park, Sang-il;Bae, Gi-Hoon;Lee, Sang-Ho
    • Journal of Korean Society of societal Security
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    • v.3 no.1
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    • pp.33-42
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    • 2010
  • This study predicts the stress history for truss bridge with local damages by using global-local model combination method. For this end, the global structure is modeled by 3D frame elements and the selected local details are modeled by shell elements. Then superposition principle enable the global-local model to be combined interactively. Because the frame model cannot consider the rigidity of gusset plate and the interation of structural members due to the complexity of stress distribution in truss connection. The section modification factors are proposed to calibrate the stiffness of global frame element. The global-local model combination is verified by comparing the numerical results with experimental data obtained from the proof loading test to the operating truss bridge. Furthermore, stress histrories of the truss bridge are generated in the consideration of the rigidity of truss connection with local damage by using the combination method.

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A Study on Damage Process Analysis for Steel Pier Subjected to Seismic Excitation (강한 지진 하중하에서 강재 교각의 손상 거동 연구)

  • Park, Yeon Soo;Park, Keun Koo;Park, Sun Joon
    • Journal of Korean Society of Steel Construction
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    • v.12 no.3 s.46
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    • pp.251-258
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    • 2000
  • Based on the numerical investigations using steel bridge pier subjected to strong seismic excitations a new approach to seismic damage assessment for steel structures and their members has been proposed in conjunction with the suggested definition of failure state. The relevant failure form of the steel pier is evaluated. It is revealed that when a seismic load has a short period, the failure of global buckling beyond the allowable displacement is more dominant than that by that of the local buckling caused by the accumulation of plastic strain. When a seismic load is not beyond this certain part, but repeats within the range of where a plastic deformation occurs, the plastic strain is accumulated on the partial element of bottom edge of steel pier and the failure occurs by the local buckling from the accumulated plastic local strain.

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