存在薄弱界面的碳纤维布复合材料加固钢筋混凝土梁剥离试验研究

置换受损保护层并外贴碳纤维复合材料（CFRP）加固锈蚀钢筋混凝土梁时，可能因新老混凝土黏结不良产生水平薄弱界面，影响其受力性能。基于此，设计10个带有水平弱界面的CFRP加固钢筋混凝土梁试件，对比分析不同界面黏结强度、加固量、保护层厚度及U形箍约束条件下加固梁的受力性能及CFRP的剥离破坏行为。结果表明，薄弱界面的存在易导致中部保护层剥离过早发生，并向端部发展，削弱了加固体系的整体性，无约束条件下纵向CFRP发生整体剥离。界面削弱越严重，加固量越大，保护层厚度越小，界面剪切传递能力越弱，剥离破坏越易发生和发展。U形箍约束能防止纵向CFRP整体剥离破坏，保证其有效受力，但不能完全防止局部剥离沿薄弱界面发展，易导致纵向CFRP在复合受力条件下过早断裂，且存在较高的端部锚固破坏的风险。

Experimental study on debonding behavior of CFRP reinforced RC beams with weak interfaces

Strengthening of corroded RC beams with externally bonded CFRP material may be affected by weak interface caused by defective bonding between new and old concrete in case of cover replacement. In this work, a total of 10 CFRP reinforced RC beams with preinstalled horizontal weak interfaces were designed for debonding test under monotonic bending. Load-deformation performance of the beams was investigated along with CFRP debonding behaviors, varying factors including interfacial weakening level, CFRP reinforcement ratio, cover thickness and lateral confinement condition. It is shown by test results that the intermediate cover delamination could be easily induced by the weak interface, which greatly impairs the integrity of the strengthening system and leads to CFRP integral debonding without lateral confinement. Degradation of shear transfer ability through the interface can be expected as a result of the interfacial weakening, increasing of CFRP reinforcement ratio and reduction of cover thickness, which raises the possibility of debonding. U-strip confinement is basically effective in maintaining the working ability of flexural CFRP and preventing the integral debonding. However, expanding of local delamination through weak interface can not be avoided completely, which consequently raise high risks of premature rupture and anchorage failure of the flexural CFRP sheet.