본 연구의 궁극적인 목표는 콘크리트 교량의 교각을 Steel Jacket으로 보강한 효과를 정량적으로 산정함으로써, 지진 발생시 도로/교통 시스템의 역할을 평가할 수 있는 자료를 제공하는 데에 있다. Steel Jacket으로 보강 시, 교각의 연성능력이 어느 정도 증가되는지, 또 그로 인해 교량의 취약 상태가 어느 정도 개선되는지를 취약도 곡선을 통하여 나타내었다. 본 연구에서 해석적으로 구한 취약도 곡선이, 과거 지진 발생시 수집된 손상 자료를 이용하여 작성된 보강이 안된 교량의 취약도 곡선을 보정하는데 사용하였다. 그 보정은 Steel Jacket 보강 전과 후의 취약도 곡선상의 중간 값들을 비교해 그 증가분 만큼을 반영하는 방식으로 수행되었다.

구조물에 내진설계를 적용하는 목적은 지진에 노출되는 구조물에 안전성과 경제성을 고려한 파괴메카니즘을 부여하는 것이다. 내진설계에 보편적으로 적용하고 있는 응답스펙트럼해석법은 선형해석법으로 구조물의 비선형 동적거동에 의한 영향은 특정 계수로 반영한다. 그러나 기존의 내진설계시방서들이 강진지역에 있는 나라들에 의해 제정 및 개정되어 왔기 때문에 응답스펙트럼 해석법 뿐만 아니라 기타의 적용규정이 강진지역에 위치한 구조물의 상황만을 고려하여 제시되었다. 따라서 중약진지역에 위치한 구조물의 내진설계에 대한 별도의 연구가 요구되고 있다. 이 연구에서는 중약진지역에 위치한 콘크리트 교량을 선정하여 비선형 동적거동을 반영하는 계수를 결정하고 응답스펙트럼 해석법을 적용하였다. 연구 결과 바탕으로 중약진지역의 교량에 대해 내진설계의 목적을 만족하는 개선된 내진설계 절차를 제시하였다.

This study is to investigate and analyze the correlation of carbonation according to strength of concrete members for bridge in marine enviroment. Also depth of carbonation according to age for 100 years is estimated by carbonation rate coefficient. As a result of the measurement, it was found that the depth of carbonation decreases with increasing strength. This is because it is considered that water-cement ratio and amount of unit cement are influenced by the concrete mixing. Also, It is anticipated that rebar corrosion due to carbonation will not occur in concrete members.

In this study, a nonlinear analysis method was proposed to investigate serviceability of rail fastening system in concrete track at the railway bridge end. The serviceability investigation method of the fastening system in concrete track is time consuming and is complex in design because of the many decks and fastening systems. In addition, there is also a case where an expensive special fastening device is installed due to the stiffness of the rail fastening device assumed to be linear and the excessive design result by the linear analysis method. Therefore, in this study, the clamping force test was performed to confirm the nonlinearity of fastener. The conventional linear analysis method and the proposed nonlinear analysis method were performed for the railway bridge model specimen with concrete tracks, and the uplift forces acting on the fastening systems were compared and analyzed.

This paper reviewed the environment of freezing-thawing cycle and snowfall frequency which represents environment of deicing agent in concrete bridges at the same time. The results showed that in terms of complex aging environment, freezing-thawing cycle and salt attack environment should be considered together. As environmental data are used in durability assessment of bridges, the results will be more reliable and practical. In addition, the quantitative evaluation method for complex aging environments will be needed in the future study.

고속도로에서 콘크리트 포장의 알칼리-골재반응 발생 구간이 증가하고 있다. 알칼리-골재반응이 발생한 콘크리트 포장은 팽창하 면서 인접 교량에 교대 변위를 발생시켜 다수의 손상을 발생시키고 있다. 현장 조사 결과 콘크리트 포장의 팽창량은 온도 신축에 의한 팽창률을 상회하면서 교량에 치명적인 하중으로 작용하고 있어 손상 방지를 위한 선제적인 조치가 필요하다. 알칼리-골재 반응에 의한 팽창 정도는 알칼 리-골재반응의 상태, 포장의 길이 및 도로구조에 따라 달라짐을 알 수 있었다. 교량의 손상 방지를 위해선 콘크리트 포장의 팽창력을 이완시켜 주는 방안이 효과적이며 콘크리트 포장의 길이가 긴 구간은 아스팔트 치환공법이 유리할 것이다.

This study is for the damage with lack of drain pipe length and it is presented for the improved references which is ｢Design and management guidelines of road drainage facilities｣.

Robotics-Assisted Bridge Inpection Tool (RABITTM) combines a capability of conventional non-destructive evaluation techniques for condition assessment of concrete bridge decks, including electrical resistivity (ER), ground-penetrating radar (GPR), impact-echo (IE), ultrasonic surface waves (USW), and a high resolution digital camera. In this study, the RABITTM platform was used to evaluate delaminaitons in a concrete bridge deck fabricated in the laboratory.

This study is for the damage with lack of drain pipe length and it is presented for the improved references which is ｢Design and management guidelines of road drainage facilities｣.

Chlorides have an strong effect on durability of concrete. So, Damage cases of RC bridge structure subjected to chloride were collected through precise safety inspection for effective maintainance of concrete bridge.

Rebound hammer test, SonReb method and concrete core test are most useful testing methods for estimate the concrete compressive strength of deteriorated concrete structures. But the accuracy of the NDE results on the existing structures could be reduced by the effects of the uncertainty of nondestructive test methods, material effects by aging and carbonation, and mechanical damage by drilling of core. In this study, empirical procedure for verifying the in-situ compressive strength of concrete is suggested through the probabilistic analysis on the 268 data of rebound and ultra-pulse velocity and core strengths obtained from 106 bridges. To enhance the accuracy of predicted concrete strength, the coefficients of core strength, and surface hardness caused by ageing or carbonation was adopted. From the results, the proposed equation by KISTEC and the estimation procedures proposed by authors is reliable than previously suggested equation and correction coefficient.

The signal characteristic of radar wave on concrete decks is determined by the attenuation of the radar due to the conversion of EM(Electromagnetic) energy to thermal energy through electrical conduction, dielectric relaxation, scattering, and geometric spreading. In this study, it is found that the attenuation of radar signal received on top rebars in bare deck concrete with 2 way travel time shows a general decreasing linear trend because of its same relative permittivity and conductivity. The radar signal after depth-normalization, can then be interpreted as being principally influenced by the content of chlorides penetrating cover concrete, which caused corrosion of rebars in bridge decks.

콘크리트 방호벽 및 중앙분리대는 교량의 부속시설이지만, 슬립폼 시공과 넓은 비표면적으로 인해 초기재령 균열이 발생하기 쉽다. 본연구에서는 대형 교량의 방호벽과 중앙분리대 콘크리트의 외관조사 및 비파괴실험을 수행하여 균열의 원인과 발생 균열의 패턴을 분석하였다. 이를 위해 시공기간을 고려하여, 건조수축, 수화열 해석이 수행되었으며, 현장의 환경조건을 고려하여 소성수축 특성을 평가하였다. 평가결과 대상구조물의 균열 원인은 철근위치에 따른 소성침하균열, 소성수축 및 건조수축에 의한 복부균열, 재료분리에 따른 상부균열로 추정할 수 있었다. 또한 균열원인과 발생 패턴을 도식화하였으며, 시공 및 재료분야에서 균열제어대책을 제안하였다. 해상위 교량에 설치하는 중앙분리대 및 방호벽 콘크리트는 환경조건 (풍속, 온도, 습도)에 매우 민감하여 초기재령균열이 쉽게 발생하므로 재료선택 및 시공방법에신중을 기해야 한다.

Natural frequency changes of an in-service concrete bridge have been monitored to analyze the dynamic characteristic according to temperature and embedded depth changes. 7 acceleration sensors are attached to the bridge, and 11 time impact experiments have been done using the impact hammer. The natural frequency has a trend to drop as the surface temperature of the body goes up. And it also has a trend to decrease as the embedded depth of the bridge foundation increases.

In this paper, analysis on chloride content and carbonation of concrete members in highway bridge is realized. As a result, it is considered that the amount of snowfall, de-icing salt, freeze and thaw affect chloride content, and concrete members with respect to carbonation in highway bridge are safety at least for now

The field application of air-coupled impact echo (IE) is evaluated in this study, where an actual in-service concrete bridge deck is tested. An IE test equipment set is deployed as part of an effort to develop new rapid measurement method. The IE data are presented as two-dimensional frequency maps. For verification of the location of shallow delamination damage, eight drilled core samples were extracted from the test area. The results show reasonably good agreement with the drilled cores.

Numerical scheme of predicting large deflection of RC column structures is discussed by developing the algorithm of equivalent lateral loading system based on theorem of virtual work.