Experimental Study On Static Force Of Bond-type Anchorage For CFRP Strand

As one of the Carbon Fiber Reinforced Polymer/Plastics(CFRP)tendons,CFRP strand has high strength,light weight,good fatigue resistance,high corrosion resistance and many other advantages.Comparing to CFRP rebar,CFRP strand with lower bending stiffness and better process performance which make it not easy to brittle fracture.So,CFRP strand expected to replace traditional steel in the field of civil engineering in the future.But the shear strength of CFRP strand is much more lower than its tensile strength,anchorage problems restrict its wide application in civil engineering.The researches on anchorage for CFRP tendons mostly focused on the rebar,anchorage for CFRP strand is less.Thus,it is has important practical and theoretical significance for the investigation on the CFRP strand anchorage.An static force experimental study is conducted to investigate the anchorage performance of CFRP strand under the financial support of Natural Science Foundation of China.This dissertation involves mainly investigations and corresponding results as follows:(1)The anchorage behaviors of bond-type anchor for CFRP strand was tested by static pull-out tests,whose bond medium is Reactive Powder Concrete(RPC).The parameters includes bond length,anchoring patterns of strand and shape parameters related to anchoring patterns.There are three different anchoring ways of anchoring patterns as bundle anchoring,decentralized anchoring and decentralized-merged anchoring.The tests results showed that the anchoring patterns of CFRP strand within the bond length had a significant influence on the anchor behavior.The CFRP strands with the anchoring patterns of the decentralized and decentralized-merged exhibited an average anchoring efficiency 2.33 times that of the bundle strand,moreover,the decentralized-merged CFRP strand has the best comprehensive performancey.(2)The CFRP strand failure modes are directly related to the shape parameters of strands.Since the unexpected shear induced wire fracture was commonly occurred in those untwisted models with the open-angle or arch-camber angle of the circumjacent wire larger than 5° or 7° for the decentralized and decentralized-merged CFRP strand cables,respectively,the proper open-angle or arch-camber angle of the circumjacent wire in the decentralized and decentralized-merged CFRP strand cables is suggested to be within the range of 3-5o or 3-7o.(3)Equations for the average bond strength and the critical anchoring length with the three different anchoring patterns were established based on the test results,which are good agreement with tests results and helpful to the design of the bonding-type anchorage system for the CFRP strands.(4)Established solid finite element models to simulating the anchorage force analysis with the software ANSYS,the bond-slip between CFRP strand and RPC was taken into account.The FEA results fits well with the test results and proves the model to be applicable.