Study on the transverse compression damage behavior of CFRP tendons in the wedge-type anchorage system

The wedge-type anchorage system is widely used for CFRP tendon anchoring due to its convenient construction, compact size and high efficiency. However, stress concentration at the gap between wedges often causes transverse damage in CFRP tendons, which compromises the safety of CFRP cables. Presently, research on the transverse compression damage behavior of CFRP tendons caused by wedges remains limited to qualitative descriptions and lacks essential theoretical support. This study investigates the transverse mechanical properties and compression damage behavior of CFRP tendons. Prismatic specimen tests for transverse compression and shear were conducted to accurately determine the transverse mechanical properties of CFRP tendons. By conducting matching shaped compression tests on CFRP tendons, the influence of different wedge gaps on compression damage behavior was examined, and the compression damage mechanism caused by wedges was analyzed. Furthermore, the LaRC05 composite material failure criterion was utilized to predict the compression damage behavior of CFRP tendons. The results indicate that compression damage of CFRP tendons in wedge-type anchorage primarily occurs due to transverse shear cracks initiating at the edges of the gaps. These cracks propagate inward under compression load until the tendons collapse. The extent of compression damage is significantly influenced by the ratio of gap width to tendon diameter O. Under the same loading conditions, the compression damage exacerbates with the increase of O. Digital Image Correlation (DIC) analysis was used to determine the critical damage state under various O values, and a linear relationship between the critical equivalent contact pressure (pc) and O was established. The LaRC05 composite material failure criterion accurately predicts the morphology of compression cracks and critical damage states of CFRP tendons. The research results of this paper provide crucial theoretical support for damage control and offer valuable guidance for the future design of anchorage systems.