Experimental study on damage control methods for RC-beams under high shear stresses

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K04364
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 23010:Building structures and materials-related
• Research Institution: Fukuyama University
• Principal Investigator: Tomatsuri Hiroyuki 福山大学, 工学部, 教授 (20736714)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 端部トラス筋 / 高せん断応力度比 / ヒンジ領域 / せん断ひび割れ / 曲げ降伏型 / せん断変形成分 / 損傷抑制

Outline of Final Research Achievements

In reinforced concrete beam members, structural design is carried out to create a rotational region called a hinge at the ends of the members, allowing the reinforcement and concrete at the ends to sustain damage during earthquakes to ensure ductility. The Building Standards Act restricts the ratio of the forces acting on the members to the material strength, but if this ratio is high, the damage to the hinge area becomes severe, reducing rotational performance and thereby lowering ductility. By reinforcing the beam-end hinges with the proposed end truss bars in this study, it is possible to suppress the occurrence of diagonal cracks, which are considered dangerous in minor to moderate earthquakes, compared to conventional structures. Additionally, during major earthquakes, the shear deformation (lateral displacement) of the hinge area can be controlled, significantly improving both strength and ductility.

Free Research Field

建築構造

Academic Significance and Societal Importance of the Research Achievements

本研究で提案したヒンジ領域に配筋する端部トラス筋は、X形配筋（主筋を部材対角状に配し曲げ抵抗・せん断抵抗に有効な配筋方法）と異なり端部断面で定着されていないので端部での引張抵抗力はない。しかし、端部トラス筋はX形配筋のようにせん断力とコンクリート圧縮強度との比の増加に比例し、せん断ひび割れ発生を遅延し、同ひび割れ発生後はひび割れ幅の拡大を抑制することができる。この現象は、せん断補強筋とは異なる対する新しい抵抗機構である。設計に利用することによって、中小地震時のひび割れや大地震時の損傷が抑制できるので、地震後の継続使用や修復・メンテナンスなどの軽減が期待でき、建物の維持管理の効率化が図れる。