손상된 콘크리트 구조물은 적절한 보수 및 보강을 통해 성능과 기능을 회복시켜야 한다. 장기간 공기 중에 노출된 콘크리트는 동결융화 작용으로 균열 및 박리를 일으켜 내부 철근의 부식을 유발하게 되는 주요 요인이 된다. 본 연구에서는 동 결융해 손상을 입은 콘크리트 교각의 FRP 보강의 연성에너지 증가 효과를 분석하였다. 보강 FRP 재료와 보강 높이, 보강 겹수 에 따라 동결융해 손상 콘크리트의 푸쉬오버 매개변수 해석을 수행하여 모멘트 곡률의 연성에너지를 비교 분석하였다. FRP 보 강 높이는 소성 힌지 이상의 높이 보강은 비효율적이며, 동결융해 손상이 커질수록 FRP 보강으로 인한 연성에너지 증가량은 커 지는 것을 확인하였다. 보강으로 인한 연성에너지 증가를 위해서는 고강도 FRP 재료보다는 높은 탄성계수를 갖는 FRP 재료가 효율적으로 나타났다. 또한 각 FRP 재료의 특성에 따라 일정 보강 겹수 이상에서 보강 효과가 나타나는 것을 확인하여 FRP 보 강으로 인한 손상된 콘크리트 교각의 연성에너지를 비교 분석하였다.

PURPOSES : This study is performed first to define the aging of road facilities and to analyze the effects of environmental factors on the deterioration of median barriers. METHODS : The aging of road facilities is defined using an analytical hierarchy process (AHP). The first stage is associated with the period, facilities, and maintenance, whereas the second stage is associated with the details. The effects of environmental factors on the deterioration are analyzed by measuring the carbonation depth and compression strength. Two regions, i.e., Gangwon and Busan, are compared separately. Top, middle, and bottom samples are analyzed for both regions. RESULTS : Based on the result of the AHP analysis, weights for period (0.220), function (0.410), and maintenance (0.370) are derived. The average carbonation depths are 11.12 and 9.78 mm for Kangwon and Busan, respectively. The estimated values of compressive strength at Gangwon are 19.7 MPa (Wonju), 24.7 MPa (Samcheok A), and 25.9 MPa (Samcheok B), 20.2 MPa (Haeundae), 23.8 MPa (Yeongdo), and 29.5 MPa (Nam). CONCLUSIONS : The aging of road facilities is associated with subpar functionality and durability. Furthermore, the median barriers constructed in the Gangwon region deteriorated more significantly than those in the Busan region owing to environmental factors. In addition, the bottom samples are more affected by aging than the top samples.

The number of aged bridges is increasing so that bridges over 30 years old account for about 11% of all bridges. Consequently, the development of a seismic performance evaluation method that considers the effects of ageing is essential for a seismic retrofitting process for improvement of the seismic safety of existing old bridges. Assessment of the damage situation of bridges after the recent earthquakes in Korea has been limited to the bearings, anchor, and concrete mortar on piers. The purpose of this study is to evaluate the seismic responses of PSC box girder bridges by considering the ageing effect of rubber bearings (RBs) and lead-rubber bearings (LRBs). The modification factor proposed by AASHTO is used to take into account the ageing effect in the bearings. PSC box girder bridges with RBs and LRBs were 3D modeled and analyzed with the OpenSEES program. In order to evaluate the ageing effect of RBs and LRBs, 40 near fault and 40 far field records were used as the input earthquakes. When considering the effect of ageing, the displacement responses and shear forces of bridge bearings (RBs and LRBs) were found to increase mostly under the analytical conditions. It was shown that the effect of ageing is greater in the case of RBs than in the case of LRBs.

신조 방식의 제조업의 특성상 경기 사이클이 존재하기 때문에, 장기적으로 이를 대처할 동반 산업이 절실하게 필요로 하고 있다. 이러한 요구에 적합한 분야가 수리조선업 분야이다. 수리조선업을 운영하기 위해서는 플로팅도크가 필수적으로 필요로 하며, 대부분 노후화된 플로팅도크를 해외로부터 수입한 후, 개/보수를 통하여 운용하고 있다. 그러나, 사용연한이 최소 30년 이상이고, 운용 시 특정 선급에 입급을 시키지 않기 때문에, 안전성에 대한 정확한 지침은 전무한 상태이다. 본 연구에서는 노후화된 플로팅도크의 계측한 두께 정 보를 활용하여, 구조강도 검토를 수행하고, 운용중인 플로팅도크의 잔류 구조강도를 분석하였다. 연구를 통하여 도출된 주요 결과들은 유사 설비의 구조 안전성 검토에 대한 가이드라인을 참조할 수 있으며, 개/보수 시 이러한 방법을 활용하면 빠른 시간 내에 최적 해를 찾을 수 있을 것으로 기대된다.

PURPOSES: The purpose of this study is to determine the effective maintenance method for a deteriorated jointed plain concrete pavement by evaluating the long-term performance of the repaired concrete overlay sections. METHODS: Long-term performance evaluation was conducted for the test section at the intersection between SeoPa and IlDong in National Road No. 37. Firstly, the distress conditions of the concrete pavement, which was constructed in December 2003, were evaluated by referring to the existing report. Secondly, the results of pretreatment, material properties, and initial performance evaluation were analyzed for the overlay test conducted in 2011. Finally, a field survey was carried out using visual inspection and nondestructive testing with a FWD in August 2018, and long-term performance evaluation was conducted for about seven years after maintenance. RESULTS: Visual inspection of the old concrete pavement showed severe damage such as joint spalling and asphalt patching. The cores taken from the old concrete had indirect tensile strength of 2.6-3.8 MPa. It is difficult to determine the freeze-thaw resistance because the average amount of air was only 1.6-2.2%, and spacing factor values were over 400㎛ regardless of location. During maintenance, overlay and partial depth repair were performed by applying three types of overlay materials which are typical in Korea. On the material side, high compressive strength (over 40 MPa) and chlorine ion penetration resistance (less than 1,000 coulomb) at 56 days were achieved. In August 2018, seven years after maintenance, visual inspection and nondestructive testing using FWD were conducted for long-term performance evaluation. Regardless of the maintenance materials, surface deficiencies such as spalling and map cracking occurred extensively near the joint. CONCLUSIONS: In conclusion, if the strength and durability index of aged concrete pavement is low, then it was determined that partial depth repair at the joint is not an effective maintenance alternative. In the case of overlay, the durability of the overlay material is considered the most important factor. In the absence of adequate reinforcement at the joint of the distressed concrete pavement, freeze-thaw damage caused by moisture penetration through the joint and failure of the old concrete are repeated, making it difficult to ensure long-term durability.

국내 고속도로의 60% 이상이 시멘트 콘크리트 포장으로 건설되었으며, 그 중 공용년수가 20년이 넘어선 구간이 절반 이상에 달하고 있다. 노후화된 시멘트 콘크리트 포장의 보수 보강은 국내의 교통여건상 우회도로가 준비되기 어렵기 때문에 조기 교통개방이 요구되며 현재까지는 주로 아스팔트 덧씌우기가 사용되고 있다. 반면에 아스팔트 덧씌우기 포장은 조기 파손으로 인해 많은 유지보수비용이 지출됨과 동시에 도로사용자의 불편을 초래하고 있다. 최근 들어 노후화 된 시멘트 콘크리트 포장의 효율적인 보강공법으로 접착식 콘크리트 덧씌우기 공법에 대해서 적용을 시도하고 있다. 따라서 아스팔트 덧씌우기 포장과 접착식 콘크리트 덧씌우기 포장의 합리적인 선택에 대한 비교 분석을 위해 포장의 연도별 파손상태에 대한 다양한 data가 필요하다. 하지만, 국내에서는 아스팔트 덧씌우기 포장과 접착식 콘크리트 덧씌우기 포장의 공용 중 파손상태에 대한 자료가 체계적으로 구축되어있지 않다. 본 연구에서는 아스팔트 덧씌우기와 접착식 콘크리트 덧씌우기 공법이 적용된 구간의 파손에 대해 충분한 자료를 구축하고 있는 미국의 LTPP Data를 이용하여, 공용성에 대해서 평가하였다. 단, 아스팔트 덧씌우기와 접착식 콘크리트 덧씌우기 공법은 파손형태가 서로 상이함으로써, 상대적인 비교를 위해 각각의 구간에 대해 포장상태지수(PCI, Pavement Condition Index)를 Database화 하였으며, 아스팔트 덧씌우기 구간과 접착식 콘크리트 덧씌우기 구간의 수명에 대해서 비교 분석을 수행하였다.

국내 고속도로의 60% 이상이 시멘트 콘크리트 포장으로 건설되었으며, 그 중 공용년수가 20년이 넘어선 구간이 절반 이상에 달하고 있다. 노후화된 시멘트 콘크리트 포장의 보수 보강은 국내의 도로 교통여건상 우회도로가 준비되기 어렵기 때문에 조기 교통개방이 요구되며 현재까지는 주로 아스팔트 덧씌우기가 사용되고 있다. 반면에 아스팔트 포장은 조기파손과 잦은 보수 때문에 보수 보강에 대한 비용이 크다. 현 시점에서 아스팔트 덧씌우기가 국내에서 가장 많이 사용되고 있는 현실을 감안할 때, 아스팔트 덧씌우기의 수명에 미치는 영향인자가 무엇인지 검토할 필요가 있다. 따라서 아스팔트 덧씌우기 공법의 성능에 영향을 미치는 인자에 대해 조사할 필요가 있으나, 국내의 경우 아스팔트 덧씌우기의 공용 중 파손상태에 대한 자료가 체계적으로 구축되어있지 않다. 본 연구에서는 아스팔트 덧씌우기 수명과 영향인자간의 상관성을 비교하기 위해 다양한 파손자료를 구축하고 있는 미국의 LTPP data를 이용하여 노후화 된 시멘트 콘크리트 포장의 아스팔트 덧씌우기에 대해 조기파손을 방지하고, 효율적인 보수 보강을 위해서 아스팔트 덧씌우기 구간의 수명에 미치는 영향인자에 대해서 통계분석을 수행하였다.

As the durability, reparability and maintainability of reinforced concrete structures are emphasized, the early perfomance degradation of concrete structures becomes a serious problem. Moreover, defects in construction materials and constructions inconsistent with the design promote the degradation of perfomance. Some worst buildings have fallen into an irreparable state within a few years. In particular, carbonation in concrete structures has been handled as the most fundamental and critical factor related to the durability of reinforced concrete. As a result, there have been efforts to develop repair materials to control carbonation. As one of these efforts, alkali recovery agents have been presented as materials for increasing the re-alkalization and durability of carbonated concrete structures. However, in applying them in the field, the performance and quality of concrete recovered after an alkali recovery agent is applied has not been fully assessed. Therefore, to examine the recovered perfomance of concrete structures resulting from the application of an alkali recovery agent, the present study assessed the depth of carbonation and the degree of deterioration of 20 years or older reinforced concrete structures, and analyzed the quality of concrete after applying an alkali recovery agent to the structures. This study aimed at providing basic infomation for the application of alkali recovery agents in the fleld. In this experiment, alkali recovery agents of the lithium silicate line, which are most common in Korea, were applied and cured using concrete of the same size. The degree of recovery was investigated according to the length of time in the initial curing stage, and based on the investigation, the maintenance perfomance of the alkali recovery agent was assessed according to the age of exposure to the open air. For these tasks, this experiment sampled concrete of different degrees of deterioration, applied alkali recovery agents to them, and observed re-alkalization and changes in the internal texture of the concrete.

Structures are currently a good condition in highway, with an average age of 14.7years. However, After 10 years, The old structure will be estimated 22% of the total structure. In this study, We have suggested the preventive maintenance methods such as preventive techniques and asset management for the deterioration of future by a lesson of failure cases of developed countries such as the United States.

Generally, reinforced concrete structures are exposed to complex deterioration. It is necessary to investigate the effect of decreasing the strength of reinforced concrete structures subjected to aging more frequently. Therefore, this study aims to analyze the resistance to freezing and thawing during complex deterioration. After the beam specimens were prepared, the freezing and thawing tests were carried out and the strength of the specimens subjected to freezing and thawing decreased as a result of 4 - point bending test.

Concrete structures are exposed to complex degradation environments depending on their environmental characteristics. The concrete members of bridges are exposed to water and salt by rivers and oceans, and there is always a possibility of freezing and thawing damage in the upper and lower part of the bridge due to the continuous heat and heavy snow in summer and winter. In this study, a freeze-thaw test method which indirectly evaluates the strength reduction of concrete according to the repeated cycle of freezing and thawing was proposed, and the strength reduction rate was measured by using the concrete specimen. As a result, the concrete strength was reduced by 20% in freeze-thaw test method. In the future, it can be used as a basic data of the study on strength of each cycles.

Domestic infrastructure facilities were built intensively in the 1970s and 1990s, and the resources required for maintenance and repair will increase sharply within the next 20 years. ‘A Comparative Study on the Classification and Financial Size of SOC(2012)’ showed that the size of the domestic infrastructure facility is shrinking. In this study, we investigated the case of asset management research and analyzed the trend of the aging of the domestic infrastructure. And then we present the direction of future research.