Effectiveness of U-Strips to Prevent CFRP Debonding in Strengthened RC Beams with Weak Interfaces
Wang Xiaogang,Li Sen and Zhou Xingang
DOI:10.11835/j.issn.1674-4764.2014.02.003
Received June 03, 2013,Revised , Accepted , Available online July 01, 2015
Volume ,2014,Pages 14-20
- Abstract
Weak interfaces may be induced during the process of substituting the damaged cover by corroded RC beams or strengthening directly with CFRP. The two possible causes are the combination between the new-old concrete and expansive cracks. In this study, nine strengthened beams were designed to investigate the effects of weak interface on CFRP debonding along with the effectiveness of conventional confinement provided by U-strips. The test results showed the structural integrity of strengthening system was impaired considerably by both types of weak interfaces. Furthermore, it easily led to CFRP debonding failure. Weaker the interface was, the less ability transfer shear forces are. Debonding failure could be effectively prevented by U-strips. Meanwhile, consequently flexural CFRP sheets performed mainly well. However, local cover delamination and premature rupture of flexural CFRP may still occur due to the effects of the weak interface. Therefore, the allowable tensile strain of flexural CFRP must be reduced, and stricter measures of confinement and anchorage must be taken in application.