Improvement of Safety Evaluation Method for Out-of-Plane Overturning of Unreinforced Masonry Infill Walls in RC Structures

2023 Fiscal Year Final Research Report

• Project/Area Number: 21H01473
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 23010:Building structures and materials-related
• Research Institution: The University of Tokyo
• Principal Investigator: Nakano Yoshiaki 東京大学, 生産技術研究所, 教授 (10212094)
• Co-Investigator(Kenkyū-buntansha): 松川 和人 東京大学, 生産技術研究所, 助教 (50709186) ; 浅井 竜也 東京大学, 生産技術研究所, 准教授 (90815846)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 無補強組積造壁 / 鉄筋コンクリート / 柱 / 面外転倒 / 面内損傷

Outline of Final Research Achievements

Reinforced concrete frames with unreinforced masonry infill walls are a common structural system found in buildings overseas and have exhibitted significant damage in past earthquakes. In particular, their out-of-plane overturning has been a major cause of injury and death, posing substantial risks to human lives and property. In this research, shake table experiments were conducted on such frames with prior in-plane deformation applied statically to investigate its effect on the out-of-plane damage to the masonry infill walls. The results strongly suggest that axial elongation associated with the repeated large non-linear lateral displacement of RC columns and the resulting loss of frictional resistance due to the gap at the boundary between beam bottom and wall top are key factors causing out-of-plane failure.

Free Research Field

建築構造

Academic Significance and Societal Importance of the Research Achievements

無補強組積造壁を含む鉄筋コンクリート造架構は日本を除く世界中で見られる建築様式であり，その面外転倒は，過去の地震時に多くの物的・人的被害を引き起こしてきた。本研究成果は，柱の塑性化に伴う軸伸び変形が骨組と組積造壁の一体性を低下させることで，組積造壁が面外転倒しやすくなることを新たに指摘するものである。そしてこの結果は，合理的な安全性評価手法や補強手法，設計手法や建設手法を提案するための大きな一助となるものである。