• Corrosion Science and Technology
• /
• 제3권4호
• /
• pp.166-171
• /
• 2004

Recent developments in Bridge Management Systems (BMS) and in Life-Cycle Cost (LCC) of bridges, have raised the need for evaluation procedure of future condition (Deterioration) of a bridge. Predicting future deterioration is not an easy task due to limited past data to extrapolate from and also due to difficulty in measuring actual deterioration such as section loss of steel on an actual steel bridge. Also, increase in live load and reduction of resistance are random variables, thus a probabilistic approach should be adopted for determining the future deterioration. Due to difficulties in evaluation of future deterioration on steel bridges, accepting uncertainties within a reasonable error, a deterministic procedure using bridge condition rating can be a useful tool for projection of future condition of bridges to identify repair and maintenance needs. The object of this paper is to determine applicability of evaluating deterioration of steel bridge components based on Bridge condition ratings. Bridge condition ratings of bridge components show wide variation for bridges of same age and does not directly correlate well with the age of the bridge and/or deterioration of the bridge. High uncertainty can be reduced by breaking down the rating and by sensitivity analysis. From refined condition rating data, generalized deterioration profile of structures based on age can be derived. Examples are shown for sample bridges in USA. Approximately, 3,000 short to medium span steel bridges were listed in the inventory database. Results show wide variation of rating factors but by subdividing the Bridge condition ratings for various categories general deterioration profiles of steel bridges can be determined.

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

• 한국강구조학회 논문집
• /
• 제19권1호
• /
• pp.1-13
• /
• 2007

강사장교의 거더와 주탑은 축력과 모멘트를 동시에 받는 보-기둥 부재이기 때문에 단일 힘을 고려하는 일반도로교의 내하율 산정식은 강사장교의 거더와 주탑에 적용할 수 없다. 현재, 사장교의 거더와 주탑에 적용 가능한 이론적인 내하율 산정방법은 아직 정립되지 않았다. 본 논문에서는 축력과 모멘트를 동시에 받는 부재의 상관공식을 적용하여 강사장교 거더와 주탑의 내하율을 산정하기 위한 식을 제안하였다. 영향선해석을 수행하여 각 부재에 압축력 최대, 정 및 부모멘트 최대의 경우에 활하중 재하 형태를 결정하였고 각 부재의 내하율 산정절차를 정리하였다. 제안된 내하율 산정방법의 타당성을 검증하기 위하여 실교량 모델인 돌산대교에 대한 적용예를 제시하였다. 일반도로교의 내하율 산정식은 돌산대교 거더와 주탑의 내하율을 과대평가 하였으며, 제안된 내하율 산정식은 축력과 모멘트를 동시에 지지하는 사장교 거더와 주탑의 거동을 적절히 반영하였다.

• 대한토목학회논문집
• /
• 제11권4호
• /
• pp.9-15
• /
• 1991

본 연구는 도로교량들의 효율적인 안전도 명가 및 내하급수 판정 전산화 시스템을 개발하는데 그 목적이 있다. 이를 위해 현행 도로교 내하급수 체계를 합리적으로 개선한 후 외관조사 또는 가용 통계자료 만으로 안전성 평가를 실시할 수 있는 신뢰성 방법에 기초한 합리적인 내하력 평가방법을 제시하고 비상작전시 군용차량의 설제적인 허용통과 급수 판정시스템을 개발하였다. 연구결과 본 연구에서 제시된 내하력 및 내하급수 판정시스템, 그리고 내하력 평가 프로그램 BRS(Bridge Rating System)은 교량의 노후도와 각종 불확실량을 체계적으로 반영한 실 내하력 평가수단으로서 장차 교량의 안전성 및 내하력 평가에 널리 활용될 수 있다고 사료되었다.

• 한국BIM학회 논문집
• /
• 제6권2호
• /
• pp.29-38
• /
• 2016

Road bridges are deteriorating gradually, and it is forecasted that the number of road bridges aging over 30 years will increase by more than 3 times of the current number. To maintain road bridges in a safe condition, current safety conditions of the bridges must be estimated for repair or reinforcement. However, budget and professional manpower required to perform in-depth inspections of road bridges are limited. This study proposes an estimation model for safety rating of road bridges by analyzing the data from Facility Management System (FMS) and Yearbook of Road Bridges and Tunnel. These data include basic specifications, year of completion, traffic, safety rating, and others. The distribution of safety rating was imbalanced, indicating 91% of road bridges have safety ratings of A or B. To improve classification performance, five safety ratings were integrated into two classes of G (good, A and B) and P (poor ratings under C). This rearrangement was set because facilities with ratings under C are required to be repaired or reinforced to recover their original functionality. 70% of the original data were used as training data, while the other 30% were used for validation. Data of class P in the training data were oversampled by 3 times, and Repeated Incremental Pruning to Produce Error Reduction (RIPPER) algorithm was used to develop the estimation model. The results of estimation model showed overall accuracy of 84.8%, true positive rate of 67.3%, and 29 classification rule. Year of completion was identified as the most critical factor on affecting lower safety ratings of bridges.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 1990년도 가을 학술발표회 논문집
• /
• pp.45-50
• /
• 1990

This study develops practical models and methods for the assessment of safety and capacity rating of existing P.C. girder bridges based on the reliability methods. One of the main objectives of the study is to propose a practical but realistic limit state model for safety assessment and LRFR rating criteria, which explicitly incorporates the degree of deterioration and damage as well as actual condition of P.C. girder bridges in terms of the damage factor and the response ratio. The damage factor proposed in the paper is defined as the ratio of the current estimated stiffness to the intact base-line stiffness of a member. Based on the observation and the results of applications to existing bridges, it may be concluded that the proposed methods for the assessment and capacity rating models, which explicitly account for the uncertainties and effects of degree of deterioration or damage, provide more realistic and consistent safety-assessment and capacity rating.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 1990년도 봄 학술발표회 논문집
• /
• pp.37-43
• /
• 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.

• Structural Monitoring and Maintenance
• /
• 제2권3호
• /
• pp.199-211
• /
• 2015

The safety and performance of bridges could be monitored and evaluated by Structural Health Monitoring (SHM) systems. These systems try to identify and locate the damages in a structure and estimate their severities. Current SHM systems are applied to a single bridge, and they have not been used to monitor the structural condition of a network of bridges. This paper propose a new method which will be used in Synthetic Rating Procedures (SRP) developed by the authors of this paper and utilizes SHM systems for monitoring and evaluating the condition of a network of bridges. Synthetic rating procedures are used to assess the condition of a network of bridges and identify their ratings. As an additional part of the SRP, the method proposed in this paper can continuously monitor the behaviour of a network of bridges and therefore it can assist to prevent the sudden collapses of bridges or the disruptions to their serviceability. The method could be an important part of a bridge management system (BMS) for managers and engineers who work on condition assessment of a network of bridges.

• 한국구조물진단유지관리공학회 논문집
• /
• 제6권1호
• /
• pp.111-118
• /
• 2002

Currently, the inspection of bridges is conduced for the parts or elements of a bridges and the results of inspection are depicted for those local elements. Therefore, the representative rating of a bridge as a whole bridge system is not presented. The purpose of the present study is to purpose a reasonable method which can yield realistic representative rating for an actual bridge. The purpose method consists of two steps, i.e, visual inspection step and safety assessment step. The importance of members is considered by introducing the weighting factors and the number of spans is also considered to obtain the representative rating of a whole bridge system. The purpose method may be efficiently used to calculate the realistic representative rating bridge structures.

• 한국농공학회지
• /
• 제44권7호
• /
• pp.36-45
• /
• 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.