建物の水平加振時の上下振動成分データを利用した鉄骨梁端部の破断検知

摘要

地震による鉄骨梁の破断は，1994年の米国ノースリッジ地震で顕在化し，わが国でも1995年兵庫県南部地震をはじめ同様の被害が見つかっている。これを受け，日米でその防止策について集中的な研究開発が行われ，対策がなされてきたものの，当然のことながら，防止策が採用される以前に設計?施工された鋼構造建物が日本国内にも多数現存する。%A vibration test for a 9-story building shows that fractures at steel beam-to-column connections change the vertical vibration characteristics at the center of the beams. By use of the result, this study proposes a fracture detecting method, in which beam vibration modes are compared by MAC (modal assurance criterion) value each other, then, fractures are detected to locate at beams related with peculiar MAC values. Finite element method analysis is executed for the 9-story building to examine the proposed method. MCS (Monte Carlo Simulation) is also executed in order to consider the effect of variation in beam vibration, which is found in practical buildings. The MCS shows that even with 15% of the maximum displacement of beam as variation, which is around half of that measured in a test for a 3-story building, the proposed method can be informative for fracture detection. Future works are to develop the criteria to judge whether to be fractured as well as to accumulate the data on practical buildings.