具有荷载作用历史的CFRP-钢界面粘结性能试验

Experiment on bonding behavior of CFRP-steel interface with load history

摘要:

为研究荷载作用历史对碳纤维增强复合材料（CFRP）加固钢结构界面粘结性能的影响,开展4种界面剪应力水平、6种持载时间的CFRP-钢双剪试件长期加载试验,对达到规定加载时间的试件进行静力拉伸破坏.根据CFRP轴向应变数据,给出了界面剪应力分布及粘结滑移曲线,考虑到界面蠕变损伤对粘结滑移本构关系的影响,在双线性模型中引入系数β、η、γ,回归分析得到了这3个系数的表达式.结果表明:胶黏剂的蠕变变形会引起界面应力重分布,随着时间的增加CFRP应变增大,界面剪应力峰值减小；加载90 d后,在12.5 mm处B组、C组、D组、E组试件界面剪应力分别减小了26.6%、59.2%、73.8%、85.4%；当界面剪应力水平较高时,应考虑界面蠕变损伤对粘结滑移曲线的影响,界面剪应力水平越高持续时间越长,蠕变损伤越显著；当CFRP粘贴长度大于有效粘结长度时,界面蠕变损伤对极限承载力没有明显影响.

Abstract:

To investigate the effects of load history on the bonding properties of carbon fiber reinforced polymer (CFRP) steel interface, long-term loading tests of CFRP-steel plate double-lap specimens were conducted under four interfacial shear stress levels and six types on loading time, and static tensile tests were carried out on the specimens which reached the specified loading time. Based on the axial strain data of CFRP, the distribution of interfacial shear stress and bond-slip curves were given. In view of the effect of interfacial creep damage on the bond-slip constitutive relations, coefficients β, η, and γ were introduced into bilinear model, and corresponding expressions were obtained by regression analysis. Results show that the creep deformation of the adhesive caused the redistribution of the interfacial stress. With the increase of time, the peak value of interfacial shear stress decreased and the strain of CFRP increased. After loading for 90 days, the interfacial shear stress of the specimens in groups B, C, D, and E at 12.5 mm decreased by 26.6%, 59.2%, 73.8%, and 85.4%, respectively. When the level of interfacial shear stress was high, the influence of interfacial creep damage on bond-slip curves should be considered, where higher interfacial shear stress and longer duration led to more significant creep damages. When the bonding length of CFRP was longer than the effective bonding length, the interfacial creep damage had no obvious effect on its ultimate bond strength.