Mesoscale simulation of pull-out performance for corroded reinforcement with stirrup confinement in concrete by 3D RBSM
Mesoscale simulation of pull-out performance for corroded reinforcement with stirrup confinement in concrete by 3D RBSM
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DOI：
10.1016/j.cemconcomp.2020.103895
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发表时间：
2021-02-01
影响因子：
10.5
通讯作者：
Nagai, Kohei
中科院分区：
文献类型：
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作者：
Avadh, Kumar;Jiradilok, Punyawut;Nagai, Kohei
混凝土保护层和箍筋的约束作用降低了由于腐蚀引起的粘结劣化速度。然而，记录的实验数据中的大分散使得很难清楚地区分保护层深度和箍筋约束对粘结退化的影响。本文利用离散的三维刚体弹簧模型(RBSM)对锈蚀钢筋混凝土模型中保护层厚度和箍筋约束对内部裂纹演化和拔出行为的影响进行了细观研究。仿真方案分为两个阶段。在阶段1中，引入不同程度的腐蚀，在保护层混凝土中产生裂缝；在阶段2中，从损坏的混凝土中拔出被腐蚀的主筋。3DRBSM的优势在于，混凝土是随机网格划分的，以减少对裂缝扩展的网格偏差，并且变形钢筋的实际几何形状是模拟的。模拟结果表明，较厚覆盖层的存在延迟了裂纹的萌生，但增加了裂纹的张开率。箍筋对裂纹萌生没有明显影响，但有效地抑制了裂纹的扩展。对模拟模型中内应力的研究表明，锈蚀过程中箍筋产生的拉应力是限制裂纹扩展的反作用围压的原因。荷载-位移曲线表明，随着腐蚀损伤的增加，抗拔能力、刚度和延性都会降低。讨论了裂缝张开和箍筋体积对粘结退化速率相对于平均表面裂缝宽度的相对影响，并与已发表的实验结果和经验公式进行了比较。
The confining effect of concrete cover and stirrups reduces the rate of bond deterioration due to corrosion. However, the large dispersion in recorded experimental data makes it difficult to clearly separate the influence of cover depth and stirrup confinement on bond degradation. This study utilises the discrete 3D Rigid Body Spring Model (RBSM) to conduct a meso-scale investigation regarding the effect of cover thickness and stirrup confinement on internal crack evolution and pull-out behaviour in corroded reinforced concrete models. The simulation scheme is divided into two stages. In stage 1, different degrees of corrosion are introduced, producing cracking in the cover concrete; in stage 2, the corroded main reinforcement is pulled out from the damaged concrete. 3D RBSM is advantageous because the concrete is randomly meshed to reduce mesh bias on crack propagation and the actual geometry of the deformed bars is modelled. The simulation results clarify that the presence of thicker cover delays crack initiation but increases the rate of crack opening. Stirrups do not have any significant effect on crack initiation but effectively restrict crack growth. An investigation of the internal stress in the simulation models shows that tensile stresses generated in stirrups during corrosion are responsible for reactionary confining pressure that restricts crack propagation. Load-displacement curves show reductions in pull-out capacity, stiffness and ductility with increasing corrosion damage. The relative influence of crack opening and stirrup volume on the rate of bond degradation with respect to average surface crack width are discussed and compared with published experimental results and an empirical equation.