施加预应力阶段CFRP布加固组合梁界面剪应力计算

Interfacial Shear Stress Calculation During Reinforcing Steel-Concrete Composite Girders with Prestressed CFRP Sheets

在预应力CFRP布加固钢与混凝土组合梁过程中,CFRP布与钢的粘结力在很多情况下决定构件是否破坏.胶结层剪切模量和CFRP布弹性模量是影响粘结力的重要因素.利用弹性理论,结合预应力CFRP布加固钢与混凝土组合梁受力特征,建立了施加预应力阶段界面剪应力的计算公式.计算结果表明,加固时组合梁跨中界面剪应力最小趋于零,越靠近CFRP布端部界面剪应力增大越快,在CFRP布端部出现明显的应力集中现象;界面剪应力随胶结层剪切模量的增大而减小,随着CFRP布弹性模量和胶结层厚度的增大而增大.

The adhesion force between prestressed CFRP sheets and steel is mainly used to control the failed girders in many cases when reinforcing the steel-concrete composite girders with prestressed CFRP sheets. The adhesion force is mainly affected by the thickness and shear modulus of adhesive layer and elastic modulus of CFRP sheets. The calculation formulas of interracial shear stress are therefore derived during prestressing on the basis of the theory of elasticity in combination with the loading conditions of the steel-concrete composite girders reinforced with prestressed CFRP sheets. The results of calculation show that the mid-span interracial shear stress approaches to zero as its minimum during reinforcing girders and, the nearer the position to the CFRP sheet end, the quicker the interracial shear stress increases with the stress concentration occuring obviously at the CFRP sheet end. The interracial shear stress decreases with increasing shear modulus of adhesive layer, and increases with increasing elastic modulus of CFRP sheet and thickness of adhesive layer.