碳纤维布用量对劣化混凝土梁加固效果的影响

Influence of CFRP Amount on the Strengthening Effect of Deteriorated Reinforced Concrete Beams

关键词:  碳纤维布  钢筋混凝土梁  劣化  抗弯性能  有效利用率

Key words:  carbon fiber reinforced polymer(CFRP)  reinforced concrete beam  deterioration  flexural behavior  effective utilization

摘要:

对劣化混凝土梁分别粘贴1层和2层碳纤维布后进行正截面受弯试验.从破坏模式、极限承载力及刚度变化等角度研究用碳纤维布加固的劣化混凝土梁（以下简称加固梁）的力学性能，重点分析碳纤维布用量对加固梁极限承载力和刚度的影响，以研究碳纤维布的有效利用率γ.结果表明：加固梁受弯时存在受压区混凝土压碎、碳纤维布拉断和黏结层剪断3种破坏模式.锈胀开裂前，加固梁极限承载力受碳纤维布用量影响程度较小；锈胀开裂后，加固梁极限承载力随碳纤维布用量增加而增大，直至再次发生受压区混凝土压碎破坏.锈蚀钢筋弹性模量与剩余截面积的乘积和碳纤维布弹性模量的比值是影响加固梁刚度变化的主要因素.碳纤维布有效利用率γ受其拉断破坏时用量Acf,min与剪断破坏时用量Acf,max影响，即Acf,min/Acf,max≤γ≤1.

Abstract:

Flexural load tests were carried out to study the mechanical properties of deteriorated reinforced concrete（RC） beams strengthened with one or two layers of carbon fiber reinforced polymer (CFRP), including the characteristics of failure mode, the ultimate strength and the stiffness. The influence of CFRP amount on the ultimate strength and stiffness were focused on. And then the effective utilization of CFRP（γ） was discussed. It is shown that three failure modes appear as the deterioration degree increases, namely, crushing of compressive concrete, the tensile fracture of CFRP and shear fracture of the bonding layer. Before cracked, the amount of CFRP has small influence on the ultimate strength, and then the influence increases as the amount of CFRP increases when the beam cracked until the compressive concrete crushed first. The product of elastic modulus and sectional area of corroded rebar to elastic modulus of CFRP ratio determines the rigidity of strengthened beams. The effective utilization of CFRP γ can be determined by the formula Acf,min/Acf, max≤γ≤1, where Acf, min and Acf, max are the amount of CFRP sheets used corresponding to tensile fracture and shear fracture of it.