钢筋混凝土结构锈胀开裂全过程仿真分析

Simulation Analysis of Whole Cracking Process due to Reinforcement Corrosion in Concrete Structures

关键词:  混凝土结构  钢筋  锈蚀  保护层  仿真分析

Key words:  concrete structure  steel bar  corrosion  cover  simulation analysis

摘要:

利用大型有限元软件DIANA，详细分析了锈蚀导致混凝土保护层开裂的全过程.仿真分析表明：混凝土保护层的锈胀开裂过程可分为内裂、扩展、外裂和内外裂缝贯通4个阶段；锈蚀产物膨胀率一定时，混凝土保护层内侧裂缝的产生主要与混凝土抗拉强度相关，其他因素影响甚微；混凝土保护层表面锈胀开裂及其裂缝贯通主要与相对保护层厚度有关，该值越大，裂缝越不容易发展；提高混凝土抗拉强度，能有效延缓锈胀裂缝的产生和发展；在相同条件下，混凝土保护层非均匀锈胀开裂时的钢筋锈蚀率较均匀锈胀开裂时低；混凝土保护层剥落的特征主要与钢筋净间距和保护层厚度的比值相关，当该值较大(＞3)时，仅角区保护层发生局部剥落，否则保护层将整体剥落.

Abstract:

By the large scale finite element software DIANA, the whole splitting process of concrete protective cover layer due to reinforcement corrosion was analyzed in detail. The simulation analysis shows that the whole cracking process can be divided into four steps, that is, internal cracking, crack growth, external cracking, and penetration cracking. At a certain level of the volumetric expansion ratio of corroded products, the internal cracks initiation at internal side of the concrete protective layer around the steel bar is mainly related to the tensile strength of concrete, and other factors have little effect on it. External cracking as well as penetration cracking are related to the ratio of protective layer thickness to bar diameter. The larger the ratio is, the more difficultly the crack propagation occurs. It is effective to improve the tensile strength of concrete by delaying crack initiation and propagation; under the same conditions, the critical corrosion ratio of reinforcing bar at cracking in non uniform corrosion is lower than that in uniform corrosion; the spalling patterns of concrete protective layer are mainly determined by the ratio of rebar clear spacing to the protective layer thickness(L/C), when the L/C ratio is large enough (larger than 3), only the corner area spalls partly. Otherwise, the whole protective layer will spall.