锈蚀钢筋混凝土梁抗弯承载力理论分析

Theoretical analysis on the bending capacity of reinforced concrete beams with corroded reinforcement

钢筋锈蚀是引起钢筋混凝土结构性能退化的主要原因。钢筋锈蚀后,除了其本身有效受力截面面积减小、强度和变形能力降低外,混凝土保护层沿受力钢筋纵向开裂以及钢筋和混凝土间黏结强度降低,最终钢筋混凝土结构耐久性性能和承载能力降低。目前,锈蚀钢筋混凝土抗弯承载力的计算方法大多基于试验结果统计之上的。在研究已有文献基础上,提出了新的锈蚀钢筋混凝土梁抗弯承载力计算的理论方法,并用试验结果进行了验证,结果令人满意。最后对钢筋锈蚀引起梁截面界限相对受压区高度的变化进行了分析,结果表明在常用的配筋率0.2%～2%范围内,钢筋混凝土梁中的受拉钢筋在钢筋锈蚀后仍能达到屈服。

Corrosion of reinforcing bars is one of the main causes which induces an deterioration of reinforced concrete（RC）structures.The reduction of effective steel bar diameter and mechanical properties,the loss of bond between steel and concrete,the microcracking of concrete along lognitudinal steel bars due to the expansion of the bars by the rust products reduces the durability the ultimate bending capacity of RC structures with corroded reinforcement.Most of available calculation methods of bending capacity of RC beams with corroded reinforcement are proposed according to the statistical test results at present.Considering both the bond behavior between corroded reinforcement and concrete and loading patterns,the theoretical calculation method of bending capacity of RC beam with corroded reinforcement was established based on analysis of state-of the-art on the performance of RC beams with corroded reinforcement.Comparison between the calculated results and the corresponding test results shows it is satisfactory.The effect of reinforcement corrosion on the relative height of the equivalent rectangle compression stress block is discussed and the results show that in commonly used reinforcement ratio range from 0.2% to 2%,tensile steel bars of RC beams still can reach the yielding strength after steel corrosion.