• Title/Summary/Keyword: Maintenance Capacity

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Load-Carrying Capacity Assessment of Deteriorated Rural Bridge

  • Kim, Han-Joong;Kim, Jong-Ok;Yang, Seung-Ie
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.44 no.7
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    • pp.36-45
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    • 2002
  • Most of rural bridges have passed 30 years of age since they were built, which have to support unexpected overload caused by changed design load and excessive amount of transportation. For these rural bridges, repairs and replacements are needed. Even though there have been attempt to estimate the safety of existing bridges deteriorated with major defects, those approaches must rely on the observable damage and subsequent decisions are made subjectively. To avoid the high cost of rehabilitation, the bridge rating must correctly represent the present load-carrying capacity. Rating engineers use a methods such as Allowable Stress Design (ASD), Load Factor Design (LFD), and Load Resistance Factor Design (LRFD) to evaluate the bridge load carrying capacity. In this paper, the load rating methods are introduced, and it is illustrated how to use the load test data from literature survey. Load test is conducted to the bridge that was built 30 years ago in rural area. From load test results, new maintenance method is suggested instead of the bridge replacement.

A Study on Assessing Disaster Response Capacity for Coastal Residents (연안거주민에 대한 재해대응능력 평가 연구)

  • Kang, Tae-Soon;Lee, Seung-Rok;Lee, Jong-Sup;Kim, Jongkyu
    • Journal of Fisheries and Marine Sciences Education
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    • v.26 no.5
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    • pp.979-990
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    • 2014
  • Recently the frequency of coastal disasters caused by global warming is increasing and the damage is becoming greater. Therefore, the Korean government is establishing various policies and measures to minimize damage. For disaster prevention, this study will evaluate the disaster response capacity of each local resident(Eup/Myeun/Dong) in coastal areas through the survey. The purpose of this study is to quantitatively understand the disaster response capacity and analyze spatial autocorrelation between hot spots(vulnerable area) and cold spots. Thus this study was conducted a survey of 311 towns(Eup/Myeun/Dong) about the disaster response capacity of coastal residents. As a result, Namhae has the highest average score(4.9). On the contrary, Hampyeong has the lowest(1.6). Coastal residents in Namhae seem to have better understanding of first aid and preventive maintenance. But coastal residents in Hampyeong seem to not have these characteristics. Afterwards, this study builds a database of disaster response capacity, and analyzes it using the spatial autocorrelation method. Finally, the area of hot spots and cold spots for disaster response capacity was quantitatively detected.

Behavior of Bearing Capacity for Shallow Foundation on a Sand overlying Clay Depending on Bearing Capacity Ratio (점토층 위 모래지반의 지지력비에 따른 얕은 기초의 지지력 거동)

  • Jung, Min Hyung;Shin, Hyo Hee;Lee, Song
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.15 no.1
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    • pp.198-208
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    • 2011
  • When a structure which has relatively low load constructs on soft clay, the bearing capacity of the ground will be improved by sand overlying clay. In this condition, verifying the bearing capacity is difficult from the P.B.T etcetera in the in-situ. So, it is needed to estimate precise bearing capacity in the design process. In this study, 2-dimensional chamber tests and FEM analyses are conducted to evaluate behavior of bearing capacity for shallow foundations on a sand overlying clay. Because depth ratio H/B and bearing capacity ratio $q_c/q_s$ are selected as main factors, height of a sand, undrained shear strength of a clay and width of a loading are designated as variables. Results from chamber tests are very similar with those of FEM analyses. And it shows that punching shear mechanism is more suitable than the equation of Okamura et al.(1998). To make continual application of load spread mechanism, the equivalent load spread angle is proposed for H/B and $q_c/q_s$. Also, the linear regression equation of critical depth ratio Hf is suggested for $q_c/q_s$.

Life Cycle Cost Optimization Considering Maintenance History of Bridge Beck and Girders (바닥판과 주형의 유지보수 이력을 고려한 LCC 최적설계)

  • Ahn Ye-Jun;Lee Hyun-Sub;Shin Yung-Seok;Park Jang-Ho
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2005.04a
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    • pp.719-726
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    • 2005
  • The optimal design was performed for the bridge superstructure composed of steel box girders and concrete deck considering life cycle cost. The service life of the superstructure was estimated, after load carry capacity curves for steel girder and concrete deck were derived on the basis of condition grade curves and maintenance histories. The object function was determined as life cycle cost, including initial cost, total maintenance cost, disposal cost and user cost, for a period of the estimated service life. The optimal design of the superstructure was performed for the various service lifes. The annual costs were used to compare calculated results and to get the most economical design. Also this paper presents reasonable idea for the use of user cost with uncertainty.

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PLC Filter Capacity Improvement and Efficiency Evaluation of Smart Street Lighting System (스마트 가로등 시스템의 전력선통신 필터 성능 개선 및 효율 평가)

  • Kim, Myung-Ho
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.58 no.2
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    • pp.154-157
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    • 2009
  • In order to give handiness to the management of the existing street lighting system which is based on the one way communication and to reduce the maintenance cost, the power line communication filter in the two way communication which is based on the CDMA communication and power line communication was improved and accordingly the stability of the communication performance was improved. Also, the efficiency of existing street lighting system and smart street lighting system was evaluated as Visual studio system. As a result, when the number of street lights is 10,000, the hours of daily work fell 50% and the number of necessary maintenance staff decreased 40%. Compared to the maintenance costs of the existing street lighting system, it could be expected to have the cut costs of almost 100 million won a year on the basis of 60 switch board and 1,200 street lights.

Development of Early Evaluation System for Concrete Quality, Construction and Maintenance (콘크리트 품질ㆍ시공ㆍ유지관리의 조기판정시스템 개발)

  • 손용우;이증빈;최미라;박봉수
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2004.10a
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    • pp.517-526
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    • 2004
  • In the resent years, the early evaluation of concrete quality, construction and maintenance has been considered as all is of major concern due to the increase of loading and the degradation of structures related with time. This paper presents evaluation of structural safety performance using measured data of construction, on the basis of a field measurements for the prevention of unreliable concrete works. Measurements analyzed in this paper are early quality condition and performance assessment, serviceability performance by cracks and deflection, rating performance by loading, durability performance by chloride attack and carbonation. Thus, a quantitative assessment model of resistance capacity was developed here to meet the requirement for deteriorated concrete structures. The model focuses on damage mechanical of concrete structures deteriorated by initial damage factors for concrete quality and environment factors such as chloride and carbonation attacks. These results could provide useful information for concrete structures interested in design, construction and maintenance.

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Analysis on a Combined Model of Competitive Bidding and Strategic Maintenance Scheduling of Generating Units (발전력의 경쟁적 입찰전략과 전략적 보수계획에 대한 결합모형 연구)

  • Lee, Kwang-Ho
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.55 no.9
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    • pp.392-398
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    • 2006
  • Maintenance scheduling of generating units (MSU) has strategic dimension in an oligopolistic market. Strategic MSU of gencos can affect a market power through capacity withdrawal which is related to bidding strategy in an generation wholesale market. This paper presents a combined framework that models the interrelation between competitive bidding and strategic MSU. The combined game model is represented as some sub-optimization problems of a market operator (MO) and gencos, that should be solved through bi-level optimization scheme. The gradient method with dual variables is also adopted to calculate a Nash Equilibrium (NE) by an iterative update technique in this paper. Illustrative numerical example shows that NE of a supply function equilibrium is obtained properly by using proposed solution technique. The MSU made by MO is compared with that by each genco and that under perfect competition market.

Application of Geotextile to ensure the Motor Pouring Ability for Paved Track (포장궤도 모르터 충진성능 확보를 위한 토목섬유의 적용)

  • Lee Ho-Ryong;Park Jong-Kyan;Hwang Seon-Keun;Lee Il-Wha
    • Proceedings of the KSR Conference
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    • 2005.11a
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    • pp.836-841
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    • 2005
  • As gravel roadbed is gradually turn down by repetitive loading of train, lasting work for maintenance and management of track is necessary to reduce the settlement of roadbed and the deterioration of track. Despite of above weak point, gravel roadbed has become a basic structure of roadbed at the present time. But request for new structure of roadbed is recently presented to settle an increased transportation capacity of track, and to solve a shortage of the labor to handle maintenance work of track. Therefore, we begin to research about maintenance-free roadbed like paved track from two years ago. In this study, a series of tests were performed to clarify the characteristics of strength and permeability of concrete specimen, which is the upper part of paved track injected by cement mortar, by type of geotextile and finally to give a basic data for application of geotextile to the lower part of paved track.

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Behavior Analysis of RC Slab Bridge according to Demage and Suggestion of Its Evaluation Process (RC 슬래브교의 손상에 따른 거동 분석 및 손상 평가 프로세스 제안)

  • Kim, Yuhee;Jeon, Jun-Chang
    • Journal of the Korean Society of Safety
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    • v.36 no.3
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    • pp.40-49
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    • 2021
  • This study surveyed damage to small and medium-sized RC slab bridges, the largest in number in Korea. Four common types of damage were identified, and their static and dynamic structural behaviors were examined through structural analysis. The degree of damage was selected as an analysis parameter for three superstructures of RC slab bridges. After structural analysis, a damage assessment process was proposed that can be used as the basis for establishing maintenance yplans for these bridges. The results of the present study can be used for the safety management of RC slab bridges, classified as bridges suspected of safety flaws or requiring maintenance in load-carrying capacity tests.

Estimation of Wind Resistance Capacity of Nielsen Arch Bridge Based on Measured Data From Monitoring System (모니터링 시스템의 계측자료를 기반으로 한 닐슨아치 교량의 내풍 안정성 평가)

  • Lee, Deok Keun;Yhim, Sung Soon
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.17 no.3
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    • pp.56-64
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    • 2013
  • The wind resistant capacity of bridges with a span of less than 200m is typically evaluated by Wind Resistant Design Manual for Highway Bridges in Japan. Also, the first vertical frequency plays an important role in the evaluation of their aerodynamic performance. An unexpected vortex-induced vibration of Nielsen arch bridge with span of 183m designed by this manual has been measured by monitoring system during typhoon. The amplitude of vibrations was about 2 times than the allowable vibration displacement. This paper presents the feature of vortex-induced vibration of this Nielsen arch bridge based on measured wind velocity, wind direction, and responses at midspan of main girder. From the result of FFT, the $1^{st}$ mode shape of the bridge is antisymmetric and the $2^{nd}$ is symmetric. Also, the dominant vibration of the bridge is the $2^{nd}$ vertical mode. According to these results, the $2^{nd}$ vertical vibration mode of this Nielsen arch bridge is prior to the first for the estimation of wind resistance capacity.