In korea, only small amount of nonstructural lightweight concrete is being used through indirect effects such as heat insulation property and soundproofing rather than structural elements due to lack of structural lightweight aggregates and lack of understanding about lightweight concrete development, etc. That`s why structural lightweight concrete to reduce weight has not been put to practical use. This study is a part of high strength lightweight aggregate concrete researches using lightweight aggregates and the purpose of this study is to find out the basic physical characteristics and tension cracking fracture characteristics of lightweight concrete. Crack Mouth Opening Displacement is measured through 3 point flexure experiment about notch beam. Load-CMOD characteristics are examined through rules of countries, characteristics of lightweight concrete and tension cracking fracture experiments. The degree of tensile characteristic alteration according to size changes of specimen and the characteristics about crack surface are analyzed. The changes of softening curve are analyzed and fracture energy is drawn through inverse analysis by the obtained Load-CMOD curve. To decide fracture energy and analysis parametric, inverse analysis is conducted and Ant Colony Method is conducted for optimization and then a way to find out optimal parameterization fracture energy is suggested.

It has been many efforts for reinforcement of existing structure since the number of earthquake has been increased world widely. Especially the occurrence of earthquake surrounding area of Korean peninsular is dramatically increased. Since the buildings in Korea have not been designed to carry the lateral and shear force caused by earthquake, the building will experience massive damages even under moderate earthquake. For this reason, the viscoelastic damper is proposed in this paper to enhance the earthquake resistance of a steel frame buildings. The viscoelastic dampers have been able to increase the overall damping of the structure significantly, hence improving the overall performance of dynamically sensitive structures. In this paper, Viscoelastic dampers designed are consists of FRP panel and viscoelastic material. In this paper, evaluate the performance of the viscoelastic damper through the experiment.

Since it is impossible to predict earthquakes, they involve more casualties and property damage compared to meteorological disasters such as heavy snow and heat waves, which can be predicted through weather forecasts. This has highlighted the need for seismic design and reinforcement. Recently, the use of composite materials as reinforcement has surged because steel plate reinforcement and section enlargement are likely to result in increased weight and physical damage to structures. This study evaluates the seismic performance of panels created from composite materials, and their guide systems. The specimens were miniature versions of actual steel structures, and displacement loads were applied in the transverse direction. Seismic performance was found to improve when structures were reinforced with seismic panels.

The need to consider torsion in the design of members of a structure has recently been increasing; therefore, many studies on torsion have been carried out. Recent research was focused on the torsional performance of concrete according to the reinforcing materials used. Of particular interest, are torsion studies of beams made of SFRC(steel fiber reinforced concrete), and there has been increasing use of SFRC at construction sites. In contrast, research on the composite PVA-ECC (polyvinyl alcohol-engineered cementitious composite) has only covered its mechanical performance, though it exhibits excellent tensile-strain performance (better than SFRC). Therefore, research on the torsion of concrete beams retrofitted using PVA-ECC is lacking. In this study, the behavior characteristics and performance of reinforced-concrete beams retrofitted by PVA-ECC was investigated experimentally. The experimental results show that the resistance to torsional cracking is increased by PVA-ECC. In addition, the strain on the rebar of the specimen was found to be reduced.

이 연구에서는 몽골 흡수굴 호수 인근에서 발견되는 설치류(땅다람쥐) 서관 구조의 일반적인 특징을 조사하였다. 설치류 서관 구조는 직선이거나 약하게 휘어진 형태이며 완만하게 경사진 형태롤 보인다. 단면상의 모양은 원형 내지는 타원형이고 지름은 주로 8-10 cm의 크기를 보인다. 버려진 서관 구조들은 대부분 토양이나 자갈에 의해 수동적으로 채워져 있다. 연구 지역에서 관찰되는 서관 구조의 크기와 구조적인 특징들은 이전에 한국에서 보고된 플라이스토세 후기 서관 구조들과 매우 유사하므로 한국에서 발견되었던 서관 구조들도 땅다람쥐과에 의해 형성된 것으로 판단된다. 하지만 서관 구조 충진물의 차이로 판단할 때 당시 한국의 연평균 강수량이 몽골에 비해 훨씬 높았던 것으로 생각된다.