In the present work, an experiment using the active infrared thermography (IRT) technique in the laboratory is conducted on a carbon fiber-reinforced polymer (CFRP) that is applied on a concrete specimen surface. The main goal is to detect debonding located between CFRP sheets as well as between the CFRP sheet and the concrete surface. In addition, the effect of the debonding depth is also studied.

In this study, the soil-structure interaction impact of a 3-hinge Concrete Modular Underground Arch (CMUA) is simulated using Abaqus/CAE. The results indicate that Abaqus/CAE is an effective tool for seismic simulation of the CMUA. Besides, the structural damage under the earthquake impact can occur locally on lining structure or its surrounding at the soils that is influenced significantly by the interaction and contact between structural parts as well as linkages of segments.

This study aims to investigate the qualitative and quantitative performance of concrete defect using Pulsed Thermography (PT) and Pulse Phase Thermography (PPT) techniques. The experimental study was carried out on a concrete specimen in-placed artificial defects with various depths and sizes. The signal-to-noise technique was used to compare the contrast between the two methods. The results showed that the thermal images obtained from PPT show clearer than those from PT (using contrast-based method).

In this study, an experimental test is conducted on a concrete specimen using passive thermography (IRT) which is an effective and modern non-destructive test (NDT) method in detecting delaminations. The present work evaluates the detectability of delaminations with different sizes during the daytime by the absolute contrast technique. In addition, the most suitable time for delamination inspection of concrete structures is also proposed.

Uplift phenomenon of container cranes occurred during the past earthquakes. Therefore, the evaluation of the potential uplift of the container cranes is an important task when the demand for trade is increasing. The objective of this study is to investigate the probability of the uplift occurrence of the container crane subjected to a wide range of earthquake intensity. The uplift results are then fitted to the log-normal cumulative distribution function (CDF).

Acoustic Emission (AE) technique applied to detect the crack occurrence of the actual beam element. An optimum position for a limited number of AE transducer was considered to accurately detect the location of the cracks in the three-dimensional space. Six AE transducer was used to detect cracks in the L400mm×H200mm×T100mm region, and several position combinations were applied. Considerable six position combinations were selected, and the weak or incorrect position detection was investigated. The optimum position applied to the experiment for actual beam element and the detected crack position was compared with the visual inspection location. A reliable crack position detecting was confirmed for loadings.

최근 발생한 지진들로 인해 한국도 지진 안전지대가 아니라는 인식이 확산되고 있다. 이에 사회 기반시설물에 대한 다각도의 내진 안전성 검토가 수행되고 있다. 전력구는 대표적인 송전시설물의 하나로 땅 속에 묻혀있는 지중 구조물이 갖는 특성으로 인해 구조물 자체의 관성, 내하력 뿐만 아니라 주변부의 지반특성을 함께 고려해야만 한다. 이를 위해서는 지반과의 상호작용을 고려할 수 있는 엄밀한 수치해석이 요구되나, 많은 비용과 시간이 요구되는 구조물-지반 상호작용해석을 모든 전력구에 적용하기엔 무리가 따른다. 본 연구에서는 지반특성과 관련된 변수를 포함하는 주요 설계변수를 독립변수로 하고 내진성능에 대한 안전율을 종속변수로 하는 직접적인 상관관계 분석을 통하여 비용이 큰 수치해석을 배제하면서도 내진안전율이 낮은 취약 전력구를 선별할 수 있는 방안을 제시하였다. 높은 상관성을 보이는 토피고와 철근량을 주요 독립변수로 설정하고 종속변수인 내진안전율과의 분포를 바탕으로 경계방정식을 도출하였다. 이를 이용하여 지진취약 전력구를 수치 해석과정 없이 선별하는 방안을 제시하였다. 대상으로 한 108개의 전력구 중 30%가 지진취약 전력구로 선별되었으며, 선별된 전력구의 내진 안전율 확인을 통해 타당한 선별 방안임을 확인하였다. 제안 기법은 상대적으로 매우 단순하며 추가적인 데이터에 적용하기 쉽고 확장이 용이하다.

The dynamic behaviour of container crane under seismic loading is a complex issue, especially for assessing uplift. The pin support is commonly used to model the contact between crane’s legs and the ground/rails in low seismicity area. However, the behaviour of the structure is quite different under high seismic intensity because the crane’s wheels are not fixed to the rails in operation. In this study, therefore, a 3-D finite element (FE) model was simulated with gap elements to consider the uplift behavior. In addition, the vertical reaction of the crane’s legs were investigated as well.

In this study, an experimental study of Impulse Thermography was carried out on a concrete specimen with in-placed artificial defects at different depths and dimensions. Then, all the data were processed by Pulse Phase Thermography technique by performing Fast Fourier Transformation. The results were compared with the absolute contrast method.

본 연구는 다성분계 고유동 모르타르의 특성에 관한 연구이다. 보통 포틀랜드 시멘트(OPC), 고로슬래그 미분말(GGBFS), 칼슘설포알루미네이트(CSA) 그리고 초속경시멘트(URSC)를 혼합한 결합재이다. GGBFS는 OPC 질량에 대해 30%(P7 series), 50%(P5 series) 그리고 70%(P3 series)치환하였고, CSA와 URSC는 10%와 20%를 치환하였다. 혼화제는 폴리카르복실계를 사용하였다. 모든 배합의 물-결합재 비(w/b)는 0.35로 일정하다. 실험은 미니슬럼프, V-funnel, 압축강도 그리고 건조수축을 측정하였다. 실험결과 CSA와 URSC의 치환율이 증가하면 혼화제 사용량, V-funnel 시간 그리고 압축강도는 증가하였다. 또한 응결시간과 건조수축은 CSA와 URSC의 치환율이 증가함에 따라 감소하였다. CSA는 건조수축을 감소시키지만 URSC는 효과가 미미하다. CSA와 URSC를 혼합한 결합제는 상호보완 작용에 의해 건조수축 감소효과가 컸다. 이는 URSC의 초기강도 향상효과와 CSA의 팽창과 장기강도 향상효과 때문이다.

The purpose of this research is to consider the qualitative and quantitative performance of reinforced concrete deteriorations using active infrared thermography (IRT) technique. An experiment of five different cases of environmental conditions was conducted on a concrete slab in laboratory. A comparison of the IRT results between normal and reinforced concrete is also discussed. The results showed that the absolute contrast between defective area and non-defective area increases with the increment of ambient temperature. Besides, the values of absolute contrast above delamination obtained from normal concrete showed high than those under effect of reinforcing steel bar.

In reality, the mono-pile foundation system of OWT (Offshore Wind Turbine) can be damaged due to uncertainties and variations in both ocean environmental loadings and/or soil resistance around the foundation. In other words, the uncertainty parameters directly influence the safety, the performance and the structural behavior of a structure. In this study, a laterally loaded mono-pile foundation for OWT structure is considered to examine the degree of influence of uncertainties in the pile-soil system of the structure by an accurate and practical reliability assessment approach.

This research aim to investigate the qualitative and quantitative performance of concrete deteriorations using Pulse Square Thermography (PST) technique. An experimental test of ten cases was conducted on a concrete slab specimen under different meteorological conditions. The results showed that the absolute contrast between defective area and sound area decreases with the falling of ambient temperature. Besides, the delamination with identical size but placed at a deeper position indicates lower absolute contrast than the shallow delamination.

본 논문에서는 기존 현수교의 정밀측량을 효과적으로 대체할 목적으로 비용과 인력의 소요가 적은 고해상도 디지털 카메라를 이용한 화상변위측정기법을 제시하고 이를 자동화 할 수 있는 프로그램을 개발하였다. 사진의 분할매수에 따른 측정의 정밀도를 고찰하기 위하여 구조물 전체를 5장, 13장, 19장으로 분할 촬영하였고 실제 공용중인 현수교를 대상으로 측정결과를 비교하였다. 개발된 화상처리기법을 이용한 측정결과는 실제 현수교의 정밀형상 측량결과와 비교적 잘 일치하였으며 측정에 소요된 비용과 시간이 매우 절감되는 것으로 나타났다. 본 연구에서 개발된 측정기법은 렌즈의 왜곡현상 보정알고리즘을 개선하고 프로그램의 자동화 비율을 높인다면 다양한 구조물에 적용될 수 있을 것으로 판단된다.