• 한국안전학회지
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• 제24권4호
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• pp.53-58
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• 2009

The importance of process for repair and reinforcement of the bridge is increasing because of the lack of the fatigue load and stress, a lowering of the bridge load carrying capacity owing to impact and oscillation, deterioration on cultivation periods of the bridge, etc. Typically the experimenter values the bridge load carrying capacity by the real rating factor and response modification factor in bridge load rating through static load test and dynamic load test. But the error occurred in reliability of response modification factor in bridge load rating according to experience of experimenter. so tests of connecting probability theory and valuation of the bridge recently. The study is to compute the real load carrying capacity of the bridge and the rating factor and response modification factor on grade of the bridge, and calculate the probability of over-loaded truck load from Weigh In Motion(WIM) Data in FORTRAN programming applying to Monte-Carlo Simulation. At the result of this study, it is acquired that the new grade is computed for the probability of over-loaded truck load and surface inspection. The A grade is over 1.95, B grade is $1.55{\sim}1.94$, C grade is $1.26{\sim}1.54$, D grade is $1.14{\sim}1.25$, E grade is under 1.13 of rating factor, respectively.

• 한국농공학회지
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• 제44권7호
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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.

• 한국구조물진단유지관리공학회 논문집
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• 제5권1호
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• pp.169-175
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• 2001

Bridge load rating calculations provide a basis for determining the safe load capacity of bridge. Load rating requires engineering judgement in determining a rating value that is applicable to maintaining the safe use of the bridge and arriving at posting and permit decisions. Load testing is an effective means in calculating the rating value of bridge. In Korea, load carrying capacity of bridge is modified by response modification factor that is determined from comparisons of measured values and analysis results. The response modification factor may be corrupted by vehicle location error that is defined as the gap of test vehicle location between load testing and analysis. In this study, the effects of vehicle location error to structural response and response modification factor are investigated, and a new method for evaluating response modification factor is proposed. The random data analysis shows that the proposed method is less sensitive to vehicle location error than the present method.

• 한국강구조학회 논문집
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• 제13권5호
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• pp.477-492
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• 2001

현재교량의 절반 가량이 성능이 저하되어 보수 보강이 요구되고 있는 실정인데 이들 교량은 제 기능을 발휘하지 못하거나 소요강도에 미달되는 경우가 있다. 필요이상의 보수보강비용 또는 재거설의 비용의 투입을 피하기 위하여 현재 상태의 내하력이 정확히 평가되어져야 한다. 교량의 평가방법으로 허용응력 평가법 (ASD) 하중계수평가법 (LFD) 하중저항계수평가법 (LRFD) 등이 현재 사용되고 있다. 본 논문에서는 허용응력 평가법 (ASD) 하중계수평가법 (LFD) 하중저항계수평가법 (LRFD)등이 비교되고 실제 교량에 적용된 하중실험의 자료들을 모았다. 그리고 하중실험의 교량평가 결과와 이론에 의한 교량평가 결과의 차이점에 대해 연구하였다. 그리고 기존에 존재하는 교량에 ASD, LFD 그리고 LRFD 방법을 적용 비교하여 어느 수준에 해당되는지를 비교 검토하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회 논문집(II)
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• pp.1273-1278
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• 2000

Bridge load rating calculations provide a basis for determining the safe load capacity of bridge. Load rating requires engineering judgement in determining a rating value that is applicable to maintaining the safe use of the bridge and arriving at posting and permit decisions. Load testing is an effective means in calculating the rating value of bridge. In Korea, load carrying capacity of bridge is modified by stress modification factor that is determined from comparisons of measured values and analysis results The stress modification factor may be corrupted by vehicle location error that is defined as the gap of test vehicle location between load testing and analysis. In this study, the effects of vehicle location error to structural response and stress modification factor are investigated, and a new method for evaluating stress modification factor is proposed. The random data analysis shows that the proposed method is less sensitive to vehicle location error than the present method.

• 복합신소재구조학회 논문집
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• 제1권1호
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• pp.34-45
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• 2010

This paper describes the design, manufacturing process, testing, application, and assessment of capacity-ratings of the first all advanced composites bridge on a public highway system. In order to verify the bridge design prior to the field application, a sub-scale bridge superstructure was built and tested in the laboratory. The field load test results were compared with those of the finite element analysis for the verification of validity. To investigate its in-service performance, field load testing and visual inspections were conducted under an actual service environment. The paper includes the presentation and discussion for advanced composites bridge capacity rating based on the stress modification coefficients obtained from the test results. The test result indicates that the advanced composites bridge has no structural problems and is structurally performing well in-service as expected. Since these composite materials are new to bridge applications, reliable data is not available for their in-service performance. The results may provide a baseline data for future field advanced composites bridge capacity rating assessments and also serve as part of a long-term performance of advanced composites bridge.

• 한국구조물진단유지관리공학회 논문집
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• 제5권3호
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• pp.115-122
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• 2001

Bridge load rating calculations provide a basis for determining the load carrying capacity of bridges. Load rating requires engineering judgement in determining a rating value that is applicable to maintaining the safe use of the bridge and arriving at posting and permit decisions. Load testing is an effective means in calculating the rating value of bridge. In Korea, load carrying capacity of bridge is modified by response modification factor that is determined from comparisons of measured values and analysis results. This paper presents the development of a method for determining the response the modification factor, using traffic loads. The proposed method is based on the results of computer simulations of traffic action effects. The simulation program generates random traffic actions for defined traffic conditions and determines the frequency distribution of maximum traffic action effects. A comparison between the proposed method and the present method shows good agreement in estimating the modified load carrying capacity of bridges.

• 한국구조물진단유지관리공학회 논문집
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• 제7권1호
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• pp.239-249
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• 2003

20, 30 년 전 시골지역에 건설된 교량들은 과도한 교통량의 증가에 따른 초과하중을 지탱해야한다. 이러한 교량들에 대해서 보수 보강이나, 교량의 교체가 필요하다. 고가의 보수 보강을 피하기 위해는, 현재 교량의 내하력을 정확히 알아야한다. 내하력 평가자들은 교량의 내하력을 평가하기 위해 허용응력법, 강도설계법, 그리고 하중저항계수법등을 사용한다. 본 연구에서는, 내하력 평가방법을 설명하고, 문헌조사를 통해 교량의 하중실험 자료의 이용에 대하여 설명한다. 그리고, 30년전에 시골지역에 건설된 교량에 대해 하중실험을 하였다. 시험자료로 부터, 교량의 교체를 대신한 새로운 보수보강 방법이 제시되었다.

• Smart Structures and Systems
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• 제32권6호
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• pp.371-382
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• 2023

Box girder bridges are now widely used in bridge construction, and it is necessary to perform load rating regularly to evaluate the load capacity of box girder bridges. Load testing is a common measure for load rating. However, the bridge must be loaded by many trucks under different loading conditions, which is time-consuming and laborious. To solve this problem, this paper proposes a load rating method for box girder bridges based on rapid moving loads testing. The method includes three steps. First, the quasi-influence factors of the bridge are obtained by crossing the bridge with rapidly moving loads, and the structural modal parameters are simultaneously obtained from the dynamic data to supplement. Second, an objective function is constructed, consisting of the quasi-influence factors at several measurement points and structural modal parameters. The finite element model for load rating is then updated based on the Rosenbrock method. Third, on this basis, a load rating method is proposed using the updated model. The load rating method proposed in this paper can considerably reduce the time duration of traditional static load testing and effectively utilize the dynamic and static properties of box girder bridges to obtain an accurate finite element model. The load capacity obtained based on the updated model can avoid the inconsistency of the evaluation results for the different structural members using the adjustment factors specified in codes.

• Structural Engineering and Mechanics
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• 제47권5호
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• pp.643-660
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• 2013

In the present work, the capacity ratings of steel truss bridges have been carried out incorporating dynamic effect of moving vehicles and its accumulating effect as fatigue. Further, corrosion in the steel members has been taken into account to examine the rating factor. Dynamic effect has been considered in the rating procedure making use of impact factors obtained from simulation studies as well as from codal guidelines. A steel truss bridge has been considered to illustrate the approach. Two levels of capacity ratings- the upper load level capacity rating (called operating rating) and the lower load level capacity rating (called inventory rating) were found out using Load and Resistance Factor Design (LRFD) method and a proposal has been made which incorporates fatigue in the rating formula. Random nature of corrosion on the steel member has been taken into account in the rating by considering reduced member strength. Partial safety factor for each truss member has been obtained from the fatigue reliability index considering random variables on the fatigue parameters, traffic growth rate and accumulated number of stress cycle using appropriate probability density function. The bridge has been modeled using Finite Element software. Regressions of rating factor versus vehicle gross weight have been obtained. Results show that rating factor decreases when the impact factor other than those in the codal provisions are considered. The consideration of fatigue and member corrosion gives a lower value of rating factor compared to those when both the effects are ignored. In addition to this, the study reveals that rating factor decreases when the vehicle gross weight is increased.