This paper presents evaluation of diffusion coefficient, passed charge, and compressive strength considering 3 substitution ratios of fly ash(0%, 30%, and 50%) and 3 different W/B ratios(37%, 42%, and 47%). Also, the relationships among diffusion coefficient, passed charge, and compressive strength are investigated focusing on the results at 28 days and 180 days. With increasing replacement ratio of FA and decreasing W/B, the resistances to chlorides(diffusion coefficient and passed charge) are improved. At 28 days and 180 days, linear relationship are observed between strength and resistance to chloride on the whole.

In the work, HPC (High Performance Concrete) samples are prepared with 3 levels of W/B (water to binder) ratios of 0.37, 0.42, and 0.27 and 3 levels of replacement ratios of 0%, 30% and 50%. Several tests containing chloride diffusion coefficient, passed charge, and compressive strength are performed considering age effect of 28 days and 180 days. Chloride diffusion is more reduced in OPC concrete with lower W/B ratio, and GGBFS concrete with 50% replacement ratio shows significant reduction of chloride diffusion in higher W/B ratio. At the age of 28 days, GGBFS concrete with 50% replacement ratio shows more rapid reduction of chloride diffusion than strength development, which reveals that abundant GGBFS replacement has effective resistance to chloride penetration even in the early-aged condition.

본 연구에서는 각기 다른 각도와 시트장수(3T, 5T 및 7T)로 제작된 카본시트 튜브로 구속된 원형 콘크리트 기둥의 압축강도 실험을 수행한 후 압축강도 실험실과 강도감소계수를 제안하였다. 실험체는 300 mm x 600 mm 크기로 제작하였으며, 탄소섬유의 각도는 90 ° ± 0 °, 90° ± 30°, 90° ± 45°, 90° ± 60°, 90° ± 75° 및 90° ± 90°이다. 압축강도 실험은 10,000 kN UTM을 이용하여 0.01 mm/sec 가력속도의 변위 제어법 으로 실험을 수행하였다. 실험결과의 회귀분석을 통하여 각도별 압축강도 및 극한변형률을 예측하는 실험식을 제안하였으며, 국내 콘크리트 부재의 설계법인 극한강도 설계법 적용을 위한 강도감소계수를 제안하였다. 강도감소계수는 Monte Carlo Analysis를 이용하여 해석을 수행하 였으며 그 값은 0.64로 제안하였다. 탄소섬유시트를 이용하여 카본튜브를 제작하는 것은 시공자의 기술력에 따라 구조성능이 좌우될 수 있으 므로 카본튜브 제작 및 시공 시 각별한 현장관리가 요구된다.

The elastic modulus of high-strength steel fiber reinforced concrete was measured 37 GPa to 41.98 GPa. Comparing the difference value of the measured stress and the stress calculated by the regression analysis results were within ± 1 MPa. Measured data acorrding to applied LPF was more stable than unapplied LPF data. but, it was slightly different.

The purpose of this research is to evaluate the standard deviation and coefficient of variation for flexural strength of lathe scrap reinforced cementitious composites. For this purpose, the cementitious composites containing lathe scrap were repeatedly made 5 times for water-binder ratio of 30%, 2mm width and 40mm length of lathe scrap, and then the standard deviation and coefficient of variation of the cementitious composites were estimated. It was observed from the test results that the standard deviation and coefficient of variation of the cementitious composites were slightly larger than plain mortar but did not matter much.

TLP (Tension Leg Platform) is the marine structure for the buckling evaluated to ensure the safety. ABAQUS program was conducted the buckling of TLP. A global model which simulated entire TLP structure has too many elements. This leads a large consumption of time and the hardware for analysis. Therefore, dividing the global model into the detailed models and the local models are significant. In this study, the buckling strength evaluation of the TLP structure members was proceed via non linear finite element analysis presented in DNV-RP-C208.

As Concrete is construction materials which is unevenly mixed with cement, aggregate and water, compressive strength and modulus of elasticity is an important factor to seize movement of structures. The purpose of this study is to investigate a correlation compressive strength and modulus of elasticity according to the size of structures, and also to analyze and compare to prediction equation of many countries.