Soundness evaluation and rehabilitation design of pre-tensioned prestressed concrete bridges after a fire

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K06520
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Civil engineering materials/Construction/Construction management
• Research Institution: Osaka Institute of Technology
• Principal Investigator: INOUE SUSUMU 大阪工業大学, 工学部, 教授 (30168447)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: プレテンションPC桁 / 加熱試験 / 最高受熱温度 / 残存耐力 / 残存プレストレス / 鋼板接着補強 / 爆裂 / 熱伝導解析

Outline of Final Research Achievements

When the heating temperature was 1100°C, the effect of heating on the residual load carrying capacity, fatigue properties and deformation properties of the pre-tensioned PC girder became significant, and an appropriate strengthening is necessary when considering continued use. In this study, cross-section restoration with polymer cement mortar and reinforcement with steel plate adhesion were performed. As a result, sufficient effects such as recovery of maximum load carrying capacity and initial rigidity, and suppression of progress of cracking and deformation were confirmed. Furthermore, the residual load carrying capacity of PC girders after a fire disaster can be estimated appropriately in safe side considering the prestress decrease rate, the decrease rate of the bond strength between prestressing steel and concrete, and the reduction in the strength of the prestressing steels which are expected from the maximum experienced temperature of prestressing steels.

Free Research Field

コンクリート工学

Academic Significance and Societal Importance of the Research Achievements

プレテンションPC橋の場合，付着特性の劣化に伴うプレストレスの減少や静的残存耐力，疲労耐力に関しては既往の知見がほとんどなく，従来ほとんど行われることのなかった実構造部材レベルでの火災加熱実験を大型加熱炉を用いて行い，その結果に基づいて，火災による損傷を受けたプレテンションPC橋の健全度評価手法や補強設計法を示すことができた点に大きな学術的意義・社会的意義を有し，その成果は今後社会基盤施設の耐火性を検討する際の貴重な資料となる。また，今後の課題や研究の方向性についても併せて示しており，学術的意義は高い。