粗糙度对FRP-混凝土界面黏结性能的影响

Effects of Roughness on Interfacial Bonding Properties Between Concrete and FRP

为了揭示混凝土表面粗糙度对FRP-混凝土界面黏结性能的影响,以灌砂法实现混凝土表面的粗糙度量化评定,完成了6种界面粗糙程度的FRP-混凝土试件界面的单剪试验,探讨了混凝土表面粗糙度对FRP-混凝土界面极限黏结力、黏结强度以及黏结滑移曲线的影响规律.研究结果表明:粗糙度为0.44的试件界面黏结性能最好,极限黏结力和黏结强度较粗糙度为0.25的试件分别提高36%~51%和124%~221%.文中还建立了基于粗糙度参数的界面有效黏结长度计算模型,发现有效黏结长度在6种界面上随粗糙度的增加总体呈降低的趋势;粗糙度小于0.56时,试件界面黏结滑移曲线在脆性区间的刚度相差无几,界面越粗糙,脆性区间越窄,而在塑性阶段,6种界面试件的黏结滑移曲线以不同斜率下降,最终发生剥离破坏时的滑移值为0.04~0.37mm.

In order to reveal the influence of concrete roughness on the interfacial bonding properties between CFRP and concrete,the roughness of concrete was quantitatively assessed through the sand-pouring method,the single shear test of CFRP-concrete interfaces were completed under 6 different conditions of interfacial roughness,and the influences of concrete roughness on the ultimate bond force,bonding strength and bonding slipping curve of the CFRP-concrete interface were investigated,finding that,as compared with the specimen with a roughness of 0.25,the specimen with a roughness of 0.44 possesses the best interfacial bonding property,and its ultimate bond force and strength improve by 36%~51% and 124%~221%,respectively.Then,a model to calculate the effective bonding length of interface was established on the basis of the roughness parameters.From this model,it is found that(1)the effective bonding length of six surfaces generally decreases with the increase of roughness;(2)the bonding slipping curves of the samples remain consistent in rigidity in the brittle area,and the rougher the interface,the shorter the brittle section;and(3)in the plastic stage,the bonding slipping curves of the samples with 6 interface types slide with different slopes,eventually resulting in a stripping damage at a slipping value of 0.04~ 0.37mm.