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研究了轴压应力对钢筋锈蚀导致混凝土保护层胀裂历程的影响。采用DIANA软件构建了保护层受钢筋非均匀锈胀作用的三维仿真模型,建立了在轴压作用下,受围压约束裸筋与混凝土内钢筋横向变形等效的方法,有效解决了对混凝土柱同时施加轴压和非均匀锈胀作用的难题。在此基础上,对不同负载水平和配筋方式的24根轴压柱的锈胀开裂历程进行了数值分析,探讨了轴压应力大小对锈胀裂缝扩展和胀裂各阶段特征锈蚀率的影响规律,并分析了轴压应力水平与混凝土强度、相对保护层厚度等其他锈胀开裂影响因素间的相关性。结果表明:轴压应力的存在改变了混凝土构件锈胀裂缝的发展趋势,影响了保护层锈胀开裂各阶段的钢筋锈蚀率;构件内多根钢筋锈蚀导致保护层破损的形态及其发生整体剥落的可能性受轴压应力水平影响显著,相同条件下随轴压应力增大,保护层发生整体剥落的可能性大大增加;钢筋非均匀锈蚀比均匀锈蚀更容易使保护层胀裂,且两者间的差异随轴压应力水平增加而加大;施加轴压应力不会改变混凝土强度和相对保护层厚度对锈胀裂缝发展的影响规律。
The influence of axial compressive stress on the cracking process of concrete cover caused by steel corrosion was studied. DIANA software was used to build a three-dimensional simulation model of the protective layer affected by non-uniform rust expansion of reinforcing steel bar. The equivalent stress-restrained beam and lateral deformation of steel bar in concrete under axial compression were established. At the same time the problem of axial pressure and non-uniform rust expansion is exerted. On the basis of this, the numerical analysis on the history of rust-cracking of 24 axial columns with different load levels and reinforcement methods was carried out. The effects of axial compressive stress on the characteristic corrosion rate of the expansion and expansion of the rust-expansion crack were discussed. Law and analyzed the correlation between the axial compressive stress level and concrete strength, relative protective layer thickness and other factors affecting the corrosion cracking. The results show that the existence of axial compressive stress changes the development tendency of the corrosive cracks in concrete members and affects the corrosion rate of steel bars in various stages of the corrosion cracking of the protective layer. The morphology of the damaged protective layer and the overall spalling Is significantly affected by the axial compressive stress level. With the increase of axial compressive stress under the same conditions, the possibility of overall peeling off of the protective layer increases greatly. The non-uniform corrosion of reinforcement more likely causes the protective layer to burst than the uniform corrosion, and both The difference between the two factors increases with the increase of the axial compressive stress. The application of axial compressive stress will not change the influence law of the concrete strength and the relative thickness of the protective layer on the development of the rust expansion cracks.