Study on Prediction of Fatigue Life of Ocean Concrete Structure and its Application to Design based on Verification of Performance

基于性能验证的海洋混凝土结构疲劳寿命预测及其在设计中的应用研究

• 批准号: 10650450
• 负责人: INOUE Shoichi
• 金额: $ 1.47万
• 依托单位: Tottori University, Faculty of Engineering
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10650450/
• 关键词: Fatigue; Fatigue strength; Fatigue life; Shear fatigue; Flexural fatigue; Marine concrete structure; Surface treatment; Carbon fiber reinforced plastic sheet; 腐食疲労

Fatigue characteristics of reinforced concrete beams were investigated under various corrosion environment including under fresh water and sea water and in air. Significant differences were observed in the fatigue strengths between the beams tested in water and those in air. That is, the fatigue strength at 2 ×10ィイD16ィエD1 cycles for the beams tested in water is smaller by 15〜25% compared to that in air. This value in the region of shear span/ effective depth ratio, a/d=3.5〜4.0 becomes smaller with increases in the value of a/d. The failure pattern of beams differs in air and in water and the failure pattern tends to occur as shear failure without the fatigue fracture of stirrup in water even though the same beam exhibits flexural failure in air. Shear failures may be separated into the shear compressive failure, the failure due to the fracture of tensile reinforcement at the point of intersection of the diagonal crack, and the diagonal tensile failure (related to the value of a/d, the … More strength of concrete and the magnitude of the applied maximum load level). The fatigue test for the beams on which the bending span only was immersed in water, was carried out. According to the flexural fatigue failure observed from these tests, the flexural failure in air was caused by the fracture of tensile reinforcement, but those in water were not only caused by the fracture tensile reinforcement but by comprehensive fatigue failure of concrete in the bending span.For the beams subjected to repetitive load under moisture conditions, the surface treatment and strengthening method using carbon fiber sheet has the effect of an increase in fatigue life. Static and fatigue tests were also conducted on strengthened reinforced concrete beams to investigate the type of failure, and deformation and strength characteristics of the beams, with the presence/absence of anchor bolts and the kind of strengthening materials (steel or CFRP(carbon fiber reinforced plastic) plate) set as the factors. As a result, (A)the CFRP plate-bonded beams, as compared with steel plate-bonded beams, were found to have (1)smaller crack widths and crack spacings under identical loadings, (2)smaller deflection and toughness at failure, and 3)larger fatigue strength, and (B)the type of fatigue failure differs depending on the kind of plate, presence of anchor bolts and the magnitude of the applied load. Lastly, from the point of the mechanism of shear fatigue failure tested in water, the shear force component carried by concrete decreases with increases in the number of repetitive loading. Though the shear force component carried by stirrups increases with increases in the number of repetitive loading, the stirrup strain was in pre-yield range.In addition, this report includes a prediction model of tensile creep strain of concrete based on micro pore behavior and fatigue strength of RC beams damaged by expansion due to alkali-aggregate reaction. Less

研究了在淡水、海水和空气中不同腐蚀环境下钢筋混凝土梁的疲劳特性。在水中和空气中测试的梁之间的疲劳强度观察到显着差异。也就是说，在水中试验的梁在2 ×10次D16次D1循环下的疲劳强度比在空气中试验的梁的疲劳强度小15 ~ 25%。在剪跨/有效深度比a/d=3.5 ~ 4.0范围内，该值随着a/d值的增大而减小。梁在空气中和水中的破坏模式不同，即使同一梁在空气中表现出弯曲破坏，其破坏模式也倾向于发生剪切破坏而不发生水中的疲劳断裂。剪切破坏可分为剪压破坏、斜裂缝交叉点处受拉钢筋断裂破坏和斜拉破坏（与a/d值有关， ...更多信息 混凝土强度和施加的最大荷载水平的大小）。进行了仅受弯跨度浸水梁的疲劳试验。根据试验中观察到的弯曲疲劳破坏，空气中的弯曲破坏是由受拉钢筋断裂引起的，而水中的弯曲破坏不仅是由受拉钢筋断裂引起的，而是由受弯跨内混凝土的综合疲劳破坏引起的。使用碳纤维片的表面处理和强化方法具有增加疲劳寿命的效果。对加固后的钢筋混凝土梁进行了静力和疲劳试验，以研究梁的破坏类型、变形和强度特性，试验中将有无锚栓和加固材料（钢板或CFRP（碳纤维增强塑料）板）设置为影响因素。结果，（A）CFRP板粘结梁与钢板粘结梁相比，发现（1）在相同载荷下裂纹宽度和裂纹间距较小，（2）破坏时的挠度和韧性较小，以及（3）疲劳强度较大，并且（B）疲劳破坏的类型根据板的种类、锚栓的存在和施加载荷的大小而不同。最后，从水中剪切疲劳破坏机理来看，混凝土所承受的剪切力分量随重复加载次数的增加而减小。尽管箍筋所承载的剪力分量随着重复荷载次数的增加而增加，但箍筋的徐变应变仍处于屈服前的范围内。此外，本文还提出了一个基于混凝土梁微孔隙特性和疲劳强度的混凝土徐变应变预测模型。少

项目成果

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S.Satoda、S.Inoue 等人：“RC 梁因膨胀而损坏的机械行为”JSCE 中国分部第 51 届年会。

斎賀洋明,井上正一他: "RCはりの曲げ圧縮疲労破壊とその寿命予測に関する研究"土木学会中国支部第52回研究発表会発表概要集. 52. (2000)

Hiroaki Saiga，Shoichi Inoue，等：“RC梁弯曲压缩疲劳破坏及其寿命预测的研究”日本土木工程学会中国分会第52次研究会议摘要集52。（2000）。

黒田保,井上正一他: "オートクレープ処理を施したモルタルのASR膨張に及ぼす各種要因の影響"材料. 48・4. 895-900 (1999)

Tamotsu Kuroda、Shoichi Inoue 等：“各种因素对蒸压砂浆 ASR 膨胀的影响”材料 48・4（1999）。

黒田晴穂,井上正一他: "膨張によって損傷を受けたRCはりの力学性状"土木学会中国支部第51回研究発表会発表概要集. 51. 585-586 (1999)

Haruho Kuroda、Shoichi Inoue 等：《膨胀破坏的 RC 梁的力学性能》日本土木工程学会中国分会第 51 届研究会议摘要集 51. 585-586 (1999)。

熊野知司,井上正一他: "コンクリートの空隙構造の変化に基づく引張クリープ予測モデルに関する研究"土木学会論文集. 613・V-42. 121-135 (1999)

Satoshi Kumano、Shoichi Inoue 等：“基于混凝土孔隙结构变化的拉伸蠕变预测模型的研究”日本土木工程学会论文集 613・V-42（1999 年）。