Bonding of carbon fibre reinforced plastic (CFRP) strips on concrete with stress gradients and process control

摘要

In recent years, carbon fibre (CF) composites have come to play a major role in structural post-strengthening. Yet, such applications have so far failed to fully exploit the high strengths and the multi-functionality of CF composites, and their potential for new-build structures is still not widely recognised [1-4]. Despite the resounding technical success achieved by pilot projects world-wide, the commercial impact of these - with the exception of post-strengthening - has remained modest. This paper makes a proposal as to how better use may be made of the strength and multi-functionality of CF composites on future construction projects. The positive results achieved with the "gradient" anchorage of parallel-wire CF composite cable [5] led EMPA to contemplate the possibility of developing a similar anchorage system for pre-stressed strip. To this end, a method was developed to allow variation of the pre-stress in the strip. This in turn permits application of the strip with a gradual reduction of pre-stress to zero at the ends, ruling out the risk of shearing in the concrete while obviating the need for elaborate end- anchorage systems or tensioning heads.