Study On Bond-Slip Behavior Between Gfrp And FRCC And Its Nonlocal Performance

Glass Fiber Reinforced Polymer/Plastic(GFRP),with its high-strength,light weight,corrosion resistance,fatigue resistance,and non-electromagnetic properties,has shown broad application prospects in the civil engineering field.Fiber Reinforced Cementitious Composites(FRCC),with its excellent tensile,crack resistance,toughness and durability,effectively make up for the brittle defects of traditional concrete.The combination of the two is the preferred measure to improve the safety and durability of traditional concrete structures and extend the service life of the structure.So far,theories on the bonding between FRP and concrete have not formed a system,tending to be extensive and different.If these theories are directly applied to the GFRP-reinforced FRCC structure,it would be biased.Furthermore,as existing bond-slip focuses on its local characteristics,the results of theoretical analysis are often different from actual ones.A large number of nonlocal theoretical research results show that there are nonlocal effects in contact problems.For this reason,this paper has carried out the study of nonlocal bond-slip between GFRP and FRCC,and analyzed the propagation characteristics of vibration waves in the axial direction of GFRP by using a nonlocal elastic rod model.The main work content as follows:(1)Through the drawing experiment of multiple groups of GFRP bars anchored in FRCC,the bonding performance of GFRP and FRCC and its influencing factors are discussed and analyzed.The increase in the diameter and anchoring length of GFRP is beneficial to increase the pull-out force,but it reduces the limit average bond stress.The increase in FRCC strength and the surface treatment of GFRP bars can effectively improve the bond stress between GFRP and FRCC.(2)Through pullout experiment by installing a strain probe at different positions that were predrilled inside an GFRP bar,the local bond-slip constitutive relationship between GFRP bars and FRCC is established.Calculate the bonding stress and relative slip of each measuring point from the data fed back from each measuring point in the anchoring length,and statistical regression to obtain the bond stress-relative slip relationship between GFRP and FRCC at different anchoringpositions,which is then corrected by the position function.The bond-slip constitutive relationship with the influence of anchor position is established.(3)Combining the three-line bond-slip relationship established by experiments,the nonlocal continuum rod model is used to theoretically analyze the bond-slip between GFRP and FRCC.The bond stress and relative slip between GFRP and FRCC and the pull-out force of the loading end can be expressed mathematically.The theoretical calculation of the loading-displacement curve of the loading end is compared with the experimental results to verify the rationality of the model and determine the most realistic nonlocal factor.Influencing factors of the maximum drawing force such as non-local factors are discussed.Finally,the calculation formula of the basic anchorage length of GFRP is given.(4)The wave equation of the non-local vibration of the GFRP rod axially under the action of unbonded and bonded damping is derived,and the expressions of displacement wave and stress wave when the GFRP anchor end is elastic,rigid,and weak boundary are solved,and given Comparative analysis of corresponding cases.