2023 Fiscal Year Final Research Report

Clarification of the effect of micro-damage caused by internal expansion on the degradation of the load-bearing performance of structural components and its loading rate dependence

Research Project

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Project/Area Number	21K04236
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Multi-year Fund
Section	一般
Review Section	Basic Section 22020:Structure engineering and earthquake engineering-related
Research Institution	Kyushu University
Principal Investigator	Tamai Hiroki 九州大学, 工学研究院, 准教授 (20509632)
Co-Investigator(Kenkyū-buntansha)	山本大介大分工業高等専門学校, 都市・環境工学科, 准教授 (40398095) 櫨原弘貴福岡大学, 工学部, 准教授 (70580182) 別府万寿博防衛大学校(総合教育学群、人文社会科学群、応用科学群、電気情報学群及びシステム工学群), システム工学群, 教授 (90532797)
Project Period (FY)	2021-04-01 – 2024-03-31
Keywords	内部膨張 / アルカリシリカ反応 / コンクリート / メゾスケールモデル / 有限要素法
Outline of Final Research Achievements	The objectives of this study were to clarify the loading rate dependence of microdamage such as cracks due to internal expansion, and to quantitatively evaluate the load-bearing capacity and fracture behavior under static and impact loading of RC beams with rebar corrosion, ASR, and their combined deterioration. To this end, many specimens with accelerated expansion were made and compression tests were performed, and also static and impact loading tests were conducted on RC beams to clarify the loading rate dependence at both the material and member levels. Furthermore, a FE based mesoscale model of concrete consisting of three phases was constructed. By using that model, the compressive properties of concrete deteriorated by ASR expansion were evaluated and the loading properties of RC beams can be roughly evaluated by using an analytical method that integrates the three-phase analysis of water movement, expansion, and elastoplastic fracture.
Free Research Field	構造工学
Academic Significance and Societal Importance of the Research Achievements	構造工学と材料学の知識を融合し，結果として得られた知見および研究成果は，劣化による耐荷性能低下の定量評価，また，致命的破壊につながる劣化の把握に役立つものであり，学術的意義は大きい。また，劣化したコンクリート・ＲＣ・ＰＣ構造物の動的耐荷性能や衝撃荷重に対する防護性能を定量的に評価することで，今後想定される自然事象（衝撃的地震動，落石，土石流など）に対する構造物の安全性を定量的に評価することができるようになり，防災や維持管理を複合的に捉えた分野に十分に生かすことができると考える。