• Title/Summary/Keyword: Accelerated Deterioration Test

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Residual capacity assessment of in-service concrete box-girder bridges considering traffic growth and structural deterioration

  • Yuanyuan Liu;Junyong Zhou;Jianxu Su;Junping Zhang
    • Structural Engineering and Mechanics
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    • v.85 no.4
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    • pp.531-543
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    • 2023
  • The existing concrete bridges are time-varying working systems, where the maintenance strategy should be planned according to the time-varying performance of the bridge. This work proposes a time-dependent residual capacity assessment procedure, which considers the non-stationary bridge load effects under growing traffic and non-stationary structural deterioration owing to material degradations. Lifetime bridge load effects under traffic growth are predicated by the non-stationary peaks-over-threshold (POT) method using time-dependent generalized Pareto distribution (GPD) models. The non-stationary structural resistance owing to material degradation is modeled by incorporating the Gamma deterioration process and field inspection data. A three-span continuous box-girder bridge is illustrated as an example to demonstrate the application of the proposed procedure, and the time-varying reliability indexes of the bridge girder are calculated. The accuracy of the proposed non-stationary POT method is verified through numerical examples, where the shape parameter of the time-varying GPD model is constant but the threshold and scale parameters are polynomial functions increasing with time. The case study illustrates that the residual flexural capacities show a degradation trend from a slow decrease to an accelerated decrease under traffic growth and material degradation. The reliability index for the mid-span cross-section reduces from 4.91 to 4.55 after being in service for 100 years, and the value is from 4.96 to 4.75 for the mid-support cross-section. The studied bridge shows no safety risk under traffic growth and structural deterioration owing to its high design safety reserve. However, applying the proposed numerical approach to analyze the degradation of residual bearing capacity for bridge structures with low safety reserves is of great significance for management and maintenance.

An Experimental Study on the Chloride Diffusion of Concrete by Experimental in Room of Individual and Combined Deterioration (단독 및 복합열화의 실내촉진실험에 의한 콘크리트의 염화물 확산에 관한 실험적 연구)

  • Kim, Young-Sun;Koo, Kyung-Mo;Kim, Young-Duck;Cho, Bong-Suk;Kim, Gyu-Yong;Kim, Moo-Han
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.05a
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    • pp.574-577
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    • 2006
  • Recently, the deterioration due to salt damage and carbonation as the main factors of deteriaoration of the domestic reinforced concrete structures has been increased. Also the national and social concern about the durability recovery of the deteriorated reinforced concrete structures is geratly being raised. Therefore, it is the final purposes of this study to develop the performance evaluation technique for durability of reinforced concrete structures deteriorated due to salt damage and carbonation with the proposal of the service life prediction method for the investigation and diagnosis of reinforced concrete structures, and accelerated test in Lab.

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A Study on the Deterioration Progress of Railway Arresters (철도용 피뢰기의 열화진전에 관한 연구)

  • 길경석;한주섭;한문섭
    • Journal of the Korean Society for Railway
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    • v.7 no.4
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    • pp.307-311
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    • 2004
  • Arresters are the best protective device on electrical power systems against transient overvoltages generated by lightning and/or switching operation. Nonetheless, arresters are deteriorated by absorption of moisture in the environments of its use, repetition in the protective operation to overvoltages, and some defects at manufacturing. It is therefore important to estimate the electrical characteristic changes of ZnO blocks. In this paper, an accelerated ageing test by a standard lightning impulse current was carried out to extract parameters needed for arrester diagnosis, and leakage current components were measured. Total energy applied to the ZnO blocks at each time is about 1,050[J] in 8/20[${\mu}\textrm{s}$] impulse current. From the experimental results, we proposed electrical parameters and leakage current level to diagnose arrester soundness.

DTS-based Temperature Monitoring and Analysis of Battery Cell Deterioration Characteristics by Temperature Condition (DTS 기반 온도 감시 및 온도 조건에서의 배터리 셀 열화 특성 분석)

  • SoonJong, Kwon;Soo-Yeon, Kim;Jin, Hwang;Sang-Kyun, Woo;Bong-Suck, Kim
    • KEPCO Journal on Electric Power and Energy
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    • v.8 no.2
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    • pp.143-149
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    • 2022
  • As ESS safety issues increase recently, there is a need to more precisely monitor the temperature of the ESS. In this paper, DTS technology for temperature monitoring of ESS batteries is introduced and the temperature measurement principle is explained. The temperature of the battery module is measured using the DTS system, and the thermal deviation between battery cells inside the battery module is analyzed. In order to analyze how thermal imbalance affects the charging and discharging performance of the battery, an accelerated degradation test was conducted. Cycle life characteristics analysis, battery surface temperature change, and AC impedance characteristics were conducted to analyze how the performance of battery cells differs according to temperature conditions.

Evaluation of Modulus of Elasticity of Wood Exposed to Accelerated Weathering Test by Measuring Ultrasonic Transmission Time (촉진 열화 목재의 초음파 전달 시간 측정을 통한 탄성 계수의 평가)

  • Park, Chun-Young;Kim, Gwang-Chul
    • Journal of the Korean Wood Science and Technology
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    • v.42 no.3
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    • pp.275-281
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    • 2014
  • In this study, accelerated weathering test was performed with wood, a major material for wooden cultural building. In order to evaluate the deterioration of wood, ultrasonic transmission times were measured to evaluate dynamic modulus of elasticity (MOE), which was verified by determining static MOE using three-point bending test. Ultrasonic transmission time was decreased with an increase in the weathering time levels (0, 500, 1000 hours) while it increased in 1500 and 2000 hours. Distribution of dynamic and static MOE was similar to that of the ultrasonic transmission time measurements. The results mean that the measurement of ultrasonic transmission time was very effective to evaluate MOE of wooden cultural buildings for their preservation and management. This method could be utilized to assess wooden cultural buildings as a way of preserving them in a scientific manner.

Service Life Prediction for Steel Bridge Coatings with Type of Coating Systems (도장계 종류에 따른 강교 도장의 공용수명 예측)

  • Lee, Chan Young;Chang, Taesun
    • Journal of Korean Society of Steel Construction
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    • v.28 no.5
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    • pp.325-335
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    • 2016
  • To predict service life of coating systems registered in Korean specifications for steel bridge coatings, field deterioration evaluation and accelerated weatherproof test were carried out, and deterioration models were drawn through regression analysis for evaluation results. For the coating systems that have not been used in field, regression analyses were carried out for the virtual evaluation results drawn by applying coordination factor to the field evaluation results for chlorinated rubber and urethane topcoat system. Service life prediction results showed that application of thermal sprayed coating (TSC) could extend service life of coatings to more than twice of general coatings.

Effect of Washing Treatment of Aged Paper Materials for Better Conservation (열화된 종이자료의 보존성 개선을 위한 세척처리 특성)

  • Lee, Kwi-Bok;Seo, Yung-Bum;Park, So-Yeon;Jeon, Yang;Shin, Jong-Soon
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.38 no.4 s.117
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    • pp.53-60
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    • 2006
  • Paper materials for long term conservation suffer slowly mechanical and chemical deterioration, the extent of which may depend upon their conservation environment. Those deterioration includes discoloring, low moisture content, acidification, and brittleness. To slow deterioration, washing treatment, deacidification, and polymer reinforcement on paper materials are usually used. One easy and simple method of fixing low moisture content and acidification was an washing method, and we used both distilled and alkali water in washing method in this study. Alkali water is electrolyzed cathode water of high pH, and has no alkali metal ions in it. Experiment showed that washing treatment with both distilled and alkali water gave improvement in raising moisture content, pH, and mechanical strength of paper materials even after severe accelerated aging test. Advantageous effect of alkali water over distilled water on preventing deterioation was also shown clearly.

Properties of Electrical Performance on Stator Coil of Traction Motor by Accelerated lest using Transient Surge (과도서지를 이용한 가속열화 시험법에 따른 견인전동기 고정자 코일의 전기적 특성 변화)

  • 박현준;장동욱;이길헌;최종선;김저우
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.16 no.9
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    • pp.783-789
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    • 2003
  • The winding problems of traction motor are the major determinant of motor's life. The root cause of winding failure is gradual deterioration of the insulation due to thermal, electrical, mechanical and environmental stresses. The aging of the insulation reduces the electrical and mechanical strength of the insulation. At same point, a voltage surge or mechanical shock from a traction motor start will fracture or break down the insulation. To achieve the expected life usually requires extensive laboratory evaluation of the insulation systems and the use of accelerated aging tests. There are several nondestructive test available for checking, the condition of motor insulation, the probable extent of aging, and the rate of which aging is taking place. So the insulation characteristics of stator coil were each analyzed by measurement of dielectric loss(tan$\sigma$), capacitance and partial discharge. The method of diagnosis is able to analyze the insulation condition and evaluate the life of the traction motor.

A Study on the Sulfate Attack Resistance of Concrete Using EAF Slag as Fine Aggregate (전기로슬래그 잔골재를 사용한 콘크리트의 황산염침식 저항성에 관한 연구)

  • Park, Moon-Seok;Kim, Young-Su
    • Journal of the Korea Institute of Building Construction
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    • v.9 no.1
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    • pp.81-87
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    • 2009
  • The purpose of this study is to investigate the sulfate attack resistance of concrete using the EAF(electric arc furnace) Slag as fine aggregate. In order to figure out the effects of magnesium sulfate solution on the durability of concrete using the EAF Slag as fine aggregate, the experiments for the immerging test in the 10% magnesium sulfate solution was executed by selecting factors such as aging processes, replacement ratio(0, 10, 20, 30, 50%), and duration of immerging. The specimens were made with various EAF slag replacements for fine aggregates and with W/C ratio fixed 0.45. compressive strength and S.D.F(Sulfate Deterioration Factor), weight change, and SEM(Scanning Electron Microscope) were tested. From the test results, EAF slag aggregate treated with accelerated aging is better than treated with air aging. The compressive strength and resistance to the sulfate attack is slightly improved with an increase in the EAF slag aggregate treated with accelerated aging replacement for aggregate.

Evaluation of Testing Method for Quality Control of Chloride Diffusivity in Concrete under chloride attack environment (콘크리트 구조물의 염해 내구성능 검토를 위한 현장 품질관리 시험법 검토)

  • Kim, Hong-Sam;Cheong, Hai-Moon;Ahn, Tae-Song;Kim, Cheol-Ho;Geon, Byung-Sub
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.04a
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    • pp.973-976
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    • 2008
  • Recently, it is increasingly reported that the deterioration of concrete structure under marine environments is due to diffusion and penetration of chloride ions. It is very important to estimate the diffusion coefficient of chloride ion in concrete. Estimation methods of chloride diffusivity by concentration difference is time-consuming. Therefore, chloride diffusivity of concrete is mainly conducted by electrically accelerated method, which is accelerating the movement of chloride ion by potential difference. However, there has not been any proper method for field quality control to closely determine the diffusion coefficient of chloride ion through accelerated tests using potential difference. In this paper, the various test methods for determination of chloride diffusion coefficient in concrete were investigated through comparison accelerated tests. From the results of estimated diffusion coefficient of chloride ion, relationship between the ponding test and acceleration test was examined.

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