• Journal of Korean Society of Steel Construction
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• v.24 no.3
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• pp.349-360
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• 2012

This paper describes a detailed assessment of the structural safety, serviceability, capacity rating and long-term performance of a glass fiber-reinforced polymer (GFRP) slab bridge superstructure. This first all-GFRP slab bridge was installed in Korea on May 2002. The GFRP slab bridge is a simply supported, its length is 10.0 m, and is designed to carry two-lane traffic and has an overall width of 8.0m. The GFRP slab bridge is a sandwich structure with a corrugated core, fabricated by hand lay-up process with E-glass fibers and vinyl ester resins. The assessment of long-term performance for the GFRP slab bridge in 2004, 2011 includes a field load testing identical to that performed in 2002. The assessment indicates that the GFRP slab bridge has no structural problems and is structurally performing well in-service as expected. The assessment may provide a baseline data for the capacity ratings assessment of the GFRP slab bridge and also serve as part of a long-term performance of all-GFRP bridge superstructure.

• Journal of Korean Society of Steel Construction
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• v.15 no.2
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• pp.187-196
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• 2003

Today, the Working Stress Rating (WSR) is being widely used for the capacity-rating and the safety assessment of railroad steel bridges. Since it cannot incorporate the uncertainties, several studies have been carried out in order to get over the incompleteness of the conventional capacity-rating and safety assessment. A system reliability-based equivalent capacity-rating method, which can evaluate the capacity of existing bridges, has been recently proposed. For more efficient reliability analysis, probabilistic parameters of the random variables in the limit-state models should be reasonably evaluated. Especially, uncertainties for live load effects must be realistically included. In this study, an improved limit-state model was used for the system reliability-based equivalent strength method. This model can incorporate the probabilistic parameters obtained from ambient measurement data. To demonstrate the applicability of the improved system reliability-based equivalent capacity rating method, this was applied to the existing steel plate girder bridge for comparison with the conventional capacity-rating and safety assessment.

• Magazine of the Korea Concrete Institute
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• v.11 no.5
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• pp.66-72
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• 1999

• Journal of the Korea Construction Safety Engineering Association
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• v.2 no.1 s.3
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• pp.82-92
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• 1992

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.5
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• pp.35-40
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• 2010

The present study proposes the strengthening method to use Conclinic Advanced FiberWrep(CAF) so as to improve Load Carrying Capacity of the RC slab bridge. In order to evaluate the strengthening performance, we strengthen 50cm per unit-width of CAF to the slab's bottom of the test bridge that designed with DB 18, then perform Static and Dynamic Field Load Test. As a result of this, 14.7% of the maximum displacement, 5.0% of the strain and 33.7% of the impact factor are reduced after strengthening. At the middle of the test spans, nominal resisting ratio is increased by 27% and Service Load Carrying Capacity is increased by 44.6%, 48.9% of each span 1 and 2. In conclusion, this study indicates that the strengthening method using CAF is very effective to improve the deteriorated RC slab bridge designed with DB 18, to the DB 24 of the first class bridge design load.

• Journal of the Korea institute for structural maintenance and inspection
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• v.6 no.4
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• pp.225-232
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• 2002

Recently the slab span-jointing method has been employed as one of the retrofit technologies to enhance the capacity of existing simple beam bridges in many cases. In general this method makes simple beam bridges behave like multi-span continuous bridges under service loads excluding self weight in company with external prestress force method in the field. In this paper the continuation effect has been studied for the retrofitted bridges by the experimental and numerical approaches. The results show that the deflections and stresses of members are reduced due to the increase of the total stiffness of bridge system and the efficiency of bridge continuation based on the slab span-jointing method is about 40 % when comparing with the case of continuous bridges.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.81-81
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• 2011

현재 국내에서 사용하고 있는 교량구조물의 성능평가방법으로는 크게 공용하중에 대한 내하율을 구하기 위하여 허용응력개념이나 강도설계 개념을 적용한 내하력 평가 기법이 사용되고 있다. 그러나 위의 방법들은 일반적으로 공용연수의 경과에 따른 재료 및 구조적 성능의 손실과 여러 가지 하중 및 환경적 요인들의 불확실성으로 인하여 발생하는 손상 및 열화를 반영하기 어렵다. 그리고 제원 및 재료물성치의 불확실성에 대한 기존 설계 자료의 DB 부족으로 기존의 평가방법에서는 이러한 시간의 경과에 따른 성능저하를 정확히 산정할 수 없어 이론상의 값과 실제 구조물과의 차이로 인한 불확실성이 존재 한다. 이에 본 연구에서는 공용년수 경과에 따른 시설물의 재료 구조적인 성능 및 거동분석 수행, 신뢰성 해석 수행을 바탕으로 교량 안전성 평가의 합리성 및 현실성을 제고하며, 구조 신뢰성 해석을 수행함으로써 실제 구조물의 강도 한계상태에 대한 파괴확률을 산정하고 그에 대응하는 위험도를 평가함으로써 안전성 검토를 수행하였다. 본 실험을 통해 1. 재료 강도, 부재 제원, 긴장력, 작용하중 등에 있어 설계 시 가정과 실제 사용 환경 사이의 변동성이 존재한다는 것을 알 수 있었으며, 2. 연구 수행 결과 일반 정밀진단 및 해석에서는 얻을 수 없는 다양하고 중요한 결과를 산출할 수 있었으며 이러한 연구 결과를 바탕으로 개선된 성능평가 기법이 제안 될 수 있음을 알 수 있었다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4A
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• pp.701-706
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• 2006

This paper describes an attempt to develop a practical method for the measurement of dead load stress in existing concrete bridges. In most cases, the dead load stress was determined by various theoretical calculations. However, the theoretical calculation cannot always provide a sufficient information on the current stress state due to lots of uncertainty. The key idea incorporated with this paper is the partial sectioning method which is able to estimate current stress state in concrete bridges subjected to dead load. The proposed method is applied to the safety assessment of actual concrete bridges and the applicability of this system is investigated.

• Journal of the Korean Society of Safety
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• v.18 no.1
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• pp.108-115
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• 2003

Bridges are rated at two levels by either Load Factor Design (LFD) or Allowable Stress Design (ASD). The lower level rating is called Inventory Rating and the upper level rating is called Operating Rating. To maintain bridges effectively, there is an urgent need to assess actual bridge loading carrying capacity and to predict their remaining life from a system reliability viewpoint. The lifetime functions are introduced and explained to predict the time-dependent failure probability. The bridge studied in this paper was built 30 years ago in rural area. For this bridge, the load test and rehabilitation were conducted. The time-dependent system failure probability is predicted with or without rehabilitation. As a case study, an optional rehabilitation is suggested, and fir this rehabilitation, load rating is computed and the time-dependent system failure probability is predicted. Based on rehabilitation costs and extended service lifes, the optimal rehabilitation is suggested.

• Journal of the Korea Concrete Institute
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• v.19 no.6
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• pp.755-762
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• 2007

For the evaluation of the load carrying capacity of the deteriorated PSC I girder bridge in service load state and the verification of the grade to the reinforcement effect of actual bridge strengthened by external prestressing tendons, the field test using vehicles is applied widely. Because this teat was executed in elastic range, the investigation of the characteristics of behavior caused by live load is only available. And it is impossible to estimate load carrying capacity in limit state and nonlinear behavior after that a crack is appeared. In this study, the 27-year-old prestressed concrete girder bridge is used and various load tests are performed, so we evaluate the behavior characteristics of the bridge in service load state and ultimate load state, and estimate the load carrying capacity of bridge. In addition, the artificial damages are induced from cutting internal tendons, and external tendons is added to strengthen it as much as vanished internal tendons. Next we compare the damage state with the strengthening state. In case of the application of external prestressing method to PSC I girder bridge, the present experiment result may decide more exactly the load carrying capacity of actual bridge, the amount for reinforcement, and the standard of quality control etc. at reinforcement work.