• Title/Summary/Keyword: deteriorated bridges

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A Study on Effect of Pre-Stressing Sequences in PSC Bridge Strengthening Method Using Continuity with External Prestressing (PSC교량 보강시 긴장력 도입순서의 영향에 관한 연구)

  • 방명석
    • Journal of the Korean Society of Safety
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    • v.16 no.4
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    • pp.123-127
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    • 2001
  • Numerous PSC bridges are stregthened by the combined use of continuity of simple spans and addition of external prestressing. In this case prestressing sequences should be carefully checked due to the effect on the stress and camber of girders and slab. Various prestressing sequences were applied in this field test and measured values were analysed. This results show that preatressing sequences affact the stress and deflection of bridge members, so the prestressing sequence should be considered at the desist and construction stages of deteriorated bridges.

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Assessment of System Reliability and Capacity-Rating of Concrete Box-Girder High-Girder Highway Bridges (R.C 박스거더교의 체계신뢰성해석 및 안전도평가)

  • 조효남;이승재;임종권
    • Proceedings of the Korea Concrete Institute Conference
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    • 1993.10a
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    • pp.195-200
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    • 1993
  • This paper develops practical and realistic reliability models and methods for the evalusion of system reliability and system reliability-based rating of R.C box-girder bridge superstructures. The precise prediction of reserved carrying capacity of bridge as a system is extremely difficult expecially when the bridges are highly redundant and significantly deteriorated or damaged. This paper proposes a new approach for the evaluation of reserved system carrying capacity of bridges in terms of equivalent system-strength, which may be defined as a bridge system-strength corresponding to the system reliability of the bridge. This can be derived from an inverse process based on the concept of FOSM form of system reliability index. The strength limit state models for R.C box-girder bridges suggested in the paper are based on the basic bending and shear strength. and the system reliability problem of box-girder superstructure is formulated as parallel-series models obtained from the FMA(Failure Mode Approach) based on major failure mechanism or critical failure states of each girder. AFOSM and IST(Importance Sampling Technique) simulation algorithm is used for the reliability analysis of the proposed models.

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Proposal of Domestic Road Bridge Deck Deterioration Models and Forecast of Replacement Demand (국내 도로교량 바닥판 열화모델 제안 및 교체 수요 예측)

  • Kim, Jin-Kwang;Jang, Il-Young
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.21 no.4
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    • pp.61-68
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    • 2017
  • Bridge decks are members that rapidly deteriorated due to various environmental factors such as heavy vehicle and deicing salt, etc. As the lifespan of bridges built in Korea increases, it is expected that the demand for replacing the deteriorated bridge decks will increase. In other countries, Accelerated Bridge Construction technology using precast decks is already actively being used as a countermeasure for replacement demand of deteriorated bridge decks. In this study, bridge decks deterioration models are proposed by collecting and analysing the condition index data of domestic bridge decks. Also, the future replacement demands of deteriorated bridge decks in terms of replacement time and replacement scale are predicted.

Field distribution factors and dynamic load allowance for simply supported double-tee girder bridges

  • Kidd, Brian;Rimal, Sandip;Seo, Junwon;Tazarv, Mostafa;Wehbe, Nadim
    • Structural Engineering and Mechanics
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    • v.82 no.1
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    • pp.69-79
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    • 2022
  • This paper discusses the field testing of two single-span double-tee girder (DTG) bridges in South Dakota to determine live load distribution factors (LLDFs) and the dynamic load allowance (IM). One bridge had seven girders and another had eight girders. The longitudinal girder-to-girder joints of both bridges were deteriorated in a way that water could penetrate and the joint steel members were corroded. A truck traveled across each of the two bridges at five transverse paths. The paths were tested twice with a crawl speed load test and twice with a dynamic load. The LLDFs and IM were determined using strain data measured during the field tests. These results were compared with those determined according to the AASHTO Standard and the AASHTO LRFD specifications. Nearly all the measured LLDFs were below the AASHTO LRFD design LLDFs, with the exception of two instances: 1) An exterior DTG on the seven-girder bridge and 2) An interior DTG on the eight-girder bridge. The LLDFs specified in the AASHTO Standard were conservative compared with the measured LLDFs. It was also found that both AASHTO LRFD and AASHTO Standard specifications were conservative when estimating IM, compared to the field test results for both bridges.

Assessment of masonry arch bridges retrofitted by sprayed concrete under in-plane cyclic loading

  • Mahdi Yazdani;Mehrdad Zirakbash
    • Structural Monitoring and Maintenance
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    • v.11 no.1
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    • pp.57-70
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    • 2024
  • Masonry arch bridges as a vital infrastructure were not designed for seismic loads. Given that masonry arch bridges are made up of various components, their contribution under the seismic actions can be very undetermined and each of these structural components can play a different role in energy dissipation. Iran is known as a high-risk area in terms of seismic excitations and according to the seismic hazard zoning classification of Iran, most of these railway infrastructures are placed in the high and very high seismicity zones or constructed near the major faults. Besides, these ageing structures are deteriorated and thus in recent years, some of these bridges using various retrofitting approaches, including sprayed concrete technique are strengthened. Therefore, investigating the behavior of these restored structures with new characteristics is very significant. The aim of this study is to investigate the cyclic in-plane performance of masonry arch bridges retrofitted by sprayed concrete technique through the finite element simulation. So, by considering the fill-arch interaction, the nonlinear behavior of a bridge has been investigated. Finally, by extracting the hysteresis and enveloping curves of the retrofitted and non-retrofitted bridge, the effect of strengthening on energy absorption and degradation of material has been investigated.

Diffusion of Chloride Ions and Evaluation of Lifetime in Highway Bridges (고속도로 교량의 염소이온확산 특성과 공용수명 평가)

  • Shin Jae In;Park Chang Ho;Lee Byeong Ju;Lim Hong Beam
    • Proceedings of the Korea Concrete Institute Conference
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    • 2005.11a
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    • pp.663-666
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    • 2005
  • Chloride attach is one of the main factors which cause the deterioration of structures. In the case highway bridges, de-icer salts very significantly increase the surface scaling due to frost action. The deteriorated concrete is subject to experience degrading of durability under chloride attach environment. In this study, diagnosis report of 147 bridges is investigated and core sample of 21 bridge decks is examined and analyzed. The results show that the cover of decks concrete is required more than 8cm for retaining bridge lifetime over 30 years.

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A RELIABILITY-BASED CAPACITY RATING OF EXISTING BRIDGES BY INCORPORATING SYSTEM IDENTIFICATION (동특성 추정 기법과 신뢰성 해법에 의한 기설교량의 내하력 판정 방법)

  • Cho, Hyo-Nam;Yun, Chung-Bang
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1990.04a
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    • pp.37-43
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    • 1990
  • This paper develops practical models and methods for the assessment of safety and rating of damaged and/or deteriorated bridges by incorporating a system identification technique for the explicit inclusion of the degree of deterioration or damage and of the actual bridge response. And, based on the proposed model, reliability-based rating methods are proposed as LRFR(Load and Resistance Factor Rating) and system reliability-index rating criteria. The proposed limit state model explicitly accounts for the degree of deterioration or damage in terms of the damage and response factors. The damage factor in the paper is proposed as the ratio of the current stiffness to the intact stiffness. Based on the observation and the results of applications to existing bridges, it may be concluded that the proposed rating models, which explicitly account for the uncertainties and the effects of degree of deterioration or damage based on the system identification technique, provide more realistic and consistent safety-assessment and capacity-rating.

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Life cycle reliability analyses of deteriorated RC Bridge under corrosion effects

  • Mehmet Fatih Yilmaz
    • Earthquakes and Structures
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    • v.25 no.1
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    • pp.69-78
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    • 2023
  • Life-cycle performance analysis of a reinforced concrete box section bridge was generated. Moreover, Monte Carlo simulation with important sampling (IS) was used to simulate the bridge material and load uncertainties. The bridge deterioration model was generated with the basic probabilistic principles and updated according to the measurement data. A genetic algorithm (GA) with the response surface model (RSM) was used to determine the deterioration rate. The importance of health monitoring systems to sustain the bridge to give services economically and reliably and the advantages of fiber-optic sensors for SHM applications were discussed in detail. This study showed that the most effective loss of strength in reinforced concrete box section bridges is corrosion of the reinforcements. Due to reinforcement corrosion, the use of the bridge, which was examined, could not meet the desired strength performance in 25 years, and the need for reinforcement. In addition, it has been determined that long-term health monitoring systems are an essential approach for bridges to provide safe and economical service. Moreover the use of fiber optic sensors has many advantages because of the ability of the sensors to be resistant to environmental conditions and to make sensitive measurements.

SYSTEM RELIABILITY-BASED EVALUATION OF BRIDGE SYSTEM REDUNDANCY AND STRENGTH (체계신뢰성에 기초한 교량의 시스템여용성 및 저항강도 평가)

  • 조효남;이승재;임종권
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1993.10a
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    • pp.240-247
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    • 1993
  • The precise prediction of reserved carrying capacity of bridge as a system is extremely difficult especially when the bridges are highly redundant and significantly deteriorated or damaged. This paper is intended to propose a new approach for the evaluation of reserved system carrying capacity of bridges in terms of equivalent system-strength, which may be defined as a bridge system-strength corresponding to the system reliability of the bridge. This can be derived from an inverse process based on the concept of FOSM form of system reliability index. It may be emphasized that this approach is very useful for the evaluation of the deterministic system redundancy and reserve strength which are measured in terms of either probabilistic system redundancy factor and reserve factor or deterministic system redundancy factor and reserve factor. The system reliability of bridges is formulated as a parallel-series model obtained from the FAM(Failure Mode Approach) based on the major failure mechanisms. AFOSM and IST methods are used for the reliability analysis of the proposed models. The proposed approach and method for the system redundancy and reserve safety/strength are applied to the safety assessment of actual RC and steel box-girder bridges. The results of the evaluation of reserved system safety or bridge system-strength in terms of the system redundancy and the system safety/strength are significantly different from those of element reliability-based or conventional methods.

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Current Status on Durability of 140 RC Bridges in Seoul Metropolitan Area (서울시내 140개 철근콘크리트 교량의 내구성 현황 분석)

  • Lee, Chang-Soo;Seol, Jin-Sung;Yoon, ln-Seok
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.4 no.3
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    • pp.161-168
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    • 2000
  • A series of in-situ inspection and measurements have been conducted to estimate rebar corrosion incidence of concrete bridges in Seoul metropolitan area. The objectives of this study were to obtain the fundamental data to analysis the causes of rebar corrosion and to establish the repair strategies of deteriorated concrete bridges due to corrosion. The results of this study had been analysed to identify the extent of chloride content and incidence of rebar corrosion by construction ages and by members. After measuring chloride content in concrete, it was concluded that about 76% of all tests on samples from concrete exceed the maximum acceptable limit to risk of chloride-induced corrosion. On the whole, slabs had the most highly chloride content. About 16% of the concrete bridges had a value lower than -350mV (vs. CSE), so it could concluded that the excessive chloride content and carbonation were a major causes of rebar corrosion. Concrete member which carbonation depth penetrates toward rebar was 39% among all tests on samples. The major causes of rebar corrosion were highly chloride content 50%, concrete carbonation 38%, poorly visual condition 6% and etc, 6%.

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