锈蚀钢筋与疲劳损伤混凝土间粘结滑移统一本构关系

Bond between reinforced steel and concrete is the interaction force between two different materials and the key for them to working together. Fatigue damage of concrete around the reinforcing steel caused by repeated loading, cracking of concrete cover and loss of transversal ribs due to reinforcement corrosion will result in a loss of bond and even a change of bond failure mode. A unified bond-slip model can scientifically describe the bond behavior between concrete and reinforced steel, including criteria of failure modes, bond-slip relationships for different failure modes and calculation of characteristic parameters for the model. Evolution of fatigue damage in neighboring concrete of reinforced steel under repeated loading will be investigated via embedded smart aggregates. A reasonable constitutive model of concrete with fatigue damage will be introduced to consider its effects, and a unified bond-slip model between uncorroded reinforced steel and damaged concrete can be obtained. Meanwhile, the impact of expansive forces and softening of cracked concrete caused by reinforcement corrosion on bond failure mode will be studied, and a unified bond-slip model will be developed for corroded steel bar and concrete. Investigation on the interaction mechanism between fatigue damage and expansive cracking of concrete will be carried out through experiments and theoretical analysis, and then bond behavior and failure mode between corrode steel bar and concrete with fatigue damage caused by repeated loading will be comprehensively investigated. Finally, a unified bond-slip model between corroded steel bar and concrete with fatigue damage will be established, considering effects of reinforcement corrosion and repeated loading. It can be used to predict time-dependent performance of reinforced concrete members subjected to repeated loading and to develop the life-cycle design theory for reinforced concrete structures.

钢筋与混凝土间良好的粘结是两种材料界面处实现应力传递并共同工作的保障。重复荷载作用下钢筋周边混凝土的疲劳损伤，钢筋锈蚀引起的混凝土胀裂以及横肋锈损都会引起粘结性能的退化乃至粘结破坏模式的转变。粘结滑移统一本构包含破坏模式的判断准则、不同破坏模式下的粘结滑移本构以及特征参数的计算，可以科学描述钢筋与混凝土间的粘结性能。课题拟通过内埋智能骨料探索重复加载过程中钢筋周边混凝土疲劳损伤演化过程，引入疲劳损伤混凝土本构，建立未锈钢筋与疲劳损伤混凝土间的粘结滑移统一本构。探明锈胀力及锈胀开裂区混凝土的软化对粘结破坏模式的影响机制，发展静力拉伸下锈蚀钢筋与混凝土间的粘结滑移统一本构。揭示混凝土疲劳损伤与锈胀开裂过程的相互影响机制，探索锈蚀钢筋与疲劳损伤混凝土间的粘结破坏模式和粘结性能，最终建立锈蚀钢筋与疲劳损伤混凝土间的粘结滑移统一本构，为重复荷载下锈蚀构件时变受力性能预测和全寿命结构设计理论奠定基础。

钢筋与混凝土间良好的粘结是两种材料界面处实现应力传递并共同工作的保障。重复荷载作用下钢筋周边混凝土的疲劳损伤，钢筋锈蚀引起的混凝土胀裂以及横肋锈损都会引起粘结性能的退化乃至粘结破坏模式的转变。粘结滑移统一本构包含破坏模式的判断准则、不同破坏模式下的粘结滑移本构以及特征参数的计算，可以科学描述钢筋与混凝土间的粘结性能。.课题开展了静力及重复荷载下的偏心拉拔试验，通过分析不同破坏模式下的粘结损伤发展，得出无论在静力作用下还是重复荷载作用下，劈裂破坏由混凝土保护层的受拉损伤控制而拔出破坏由肋前混凝土剪压损伤控制，并根据混凝土保护层的极限约束力提出了粘结破坏模式的简单判别准则。.钢筋锈蚀引起的混凝土保护层胀裂是导致锈蚀变形钢筋与混凝土粘结性能退化的主要原因，课题基于厚壁圆筒模型建立了保护层锈胀开裂的均质模型，利用有限差分法计算得到锈胀开裂全过程曲线;基于离散单元法建立了混凝土保护层锈胀开裂细观模型，考虑粗骨料分布的随机性较为真实地模拟了保护层锈胀开裂的随机过程，进而研究了锈蚀钢筋与混凝土间的粘结性能退化规律。.通过疲劳粘结试验探究了重复荷载作用下钢筋与混凝土间相对滑移及混凝土保护层受拉损伤的发展规律，讨论了不同粘结破坏模式的疲劳破坏准则，分析了疲劳荷载历史对粘结性能参数的影响，建立了考虑疲劳加载历史影响的钢筋混凝土粘结应力滑移本构。.通过试验手段研究了锈蚀钢筋周围的粘结疲劳损伤演化规律，探究了钢筋锈蚀与重复荷载共同作用下的粘结性能退化规律，考虑钢筋锈蚀和疲劳荷载的影响，对劈裂破坏模式下的粘结强度理论模型和粘结全过程数值模型进行修正，建立了锈蚀钢筋与疲劳损伤混凝土间的粘结性能计算模型。.课题成果为锈蚀钢筋混凝土构件性能退化的预测和时变可靠性的分析乃至混凝土结构的全寿命设计理论的创建奠定了基础。