상시진동계측을 이용한 항로표지시설물의 구조건전성 평가 시스템 개발

Abstract

Korea is a peninsular country and the west coastal region comes in contact with the eastern part of China by the Yellow Sea. The Yellow Sea is well-known as its distinguished features such as its high difference between the rise and fall of the tide, a low water depth, and many submerged rocks. Especially, the submerged rocks can be an obstacle for navigating vessels along the coast. To avoid any collision between vessels and rocks, about 300 Aids to Navigation facilities including offshore fixed light structure have been constructed. The Aids to Navigations are usually set on the rocks and it is important to maintain a certain level of structural integrity of the structures not to be had over and be collapsed by typhoons and so on. Generally structural defects occur at joint between a superructure and a rock, because of the high speed of current and wave, while the super-structures are usually maintained healthy owing to the land construction. However, the structural integrity evaluation by visual inspection or any other non-destructive testing methods is not so easy due to the coastal environment. To this end, a systematic procedure is proposed to evaluate the structural deficiency qualitatively utilizing the ambient vibration measurement. The structure has a certain level of ambient motions due to the external loadings such as wave and wind, and the vibration data can be measured and utilized to extract the modal properties such as natural frequencies and mode shapes. The proposed method is applied to evaluate the structural deficiency of an old and a relatively new offshore fixed light structures.Structural integrity assessment technique is proposed using ambient vibration measurements for light beacon structures. When the foundation of a structure is submerged under water, the visual inspection is difficult to be carried out. In such a case, the vibration-based structural integrity assessment can be exercised very efficiently because the vibration character