钢筋非均匀锈蚀引起混凝土保护层内裂分析

根据自然环境下保护层锈胀开裂前的钢筋锈蚀形态,将锈蚀层简化为半椭圆状的非均匀分布,从而建立了钢筋非均匀锈蚀理论模型。经过求解得到了混凝土中锈胀应力理论解,并与有限元计算结果对比,验证了理论解的精确性。根据理论解可知最大周向应力在水平轴上,因此锈蚀层的发展会首先引起保护层内部水平裂纹的产生。增加钢筋直径可有效减低锈胀应力,提高结构抗锈裂的能力。与均匀锈蚀理论模型对比结果表明:均匀锈蚀要远小于非均匀锈蚀条件下的临界锈蚀层厚度,均匀锈蚀的计算结果偏于保守。因此,对锈胀问题进行理论分析时,应采用更接近真实锈蚀形态的非均匀锈蚀模型。

Analysis on the internal cracking of concrete cover caused by rebar non-uniform corrosion

According to the corrosion development of rebar that occurred before concrete cover cracking under natural conditions, the corrosion layer was simplified as a non-uniform distribution with semi-elliptical shape to model the non-uniform corrosion of rebar. Formulas were obtained to calculate the corrosion expansion stress of the concrete cover by using theoretical analysis, and its accuracy was verified by compared with finite element results. According to the theoretical solution, the maximum circumferential stress is on the horizontal axis, so the development of the corrosion layer can induce the horizontal internal crack inside the cover. Increasing rebar diameter can effectively decrease the corrosion-expansion stress and improve the ability of anti-rust crack of reinforced concrete structure. Calculated results indicate that the critical thickness of corrosion layer in the uniform corrosion model is far less than that in the non-uniform corrosion model and the result of uniform corrosion model is conservative. Therefore, the non-uniform corrosion model is validated to be much closer to the truth to analysis the corrosion problems.