An Experimental Investigation On The Anchorage Capacity Of FRP Anchors

Recently,the retrofitting and strengthening of existing concrete structures has become increasingly necessary due to its service age,environmental degradation,errors in design and construction.Numerous experimental investigations have shown that FRP is advanced and efficient in externally bonded reinforcement on concrete and hence applied extensively.However,a failure mode of premature debonding that is able to severely hinder the effectiveness of FRP at usable strains occurs very commonly and frequently.Researchers all over the world have conducted investigations on this subject for several decades.The use of U-wraps,steel anchors,SFRP and FRP anchor were proposed.The spray layup process of FRP has the advantages of high integrity and bonding capacity with concrete structures.Moreover,FRP anchor,with easy access and marked properties of corrosion resistance as well as environmental durability,is particularly promising.However,investigations on anchorage capacity of FRP anchors are limited,which results in the block of using FRP anchors in engineering.On the other hand,few researches have ever paid attention on the combine of SFRP and FRP anchors.The tensile strength of composites of SFRP with pre-designed parameters was tested at the first experiments of this paper in order to certificate the feasibility of SFRP on strengthening undamaged concrete blocks.What's more,the pullout strength of strengthened concrete was tested by the pullout experiment according to ACI of method of experiments.The result of the pullout tests is analyzed to investigate the anchorage capacity of FRP anchors.Several results are received:(1)FRP anchors are efficient in preventing debonding failure of FRP-to-concrete;(2)the anchorage depth is the most influential factor on the anchorage capacity of FRP anchors and the longer the higher;(3)the content of fibers is positive correlated with anchorage capacity but the impact is reducing as the increment of fiber content;(4)the compressive strength of concrete hardly does impact on the anchorage capacity of FRP anchors;(5)the mechanical properties of SFRP is also the influential parameter to anchorage capacity of anchors;(6)under the fixed parameter setting in this thesis,the FRP anchor with depth of 45 mm and fiber rovings of 4 performs the best in anchorage capacity;(7)thetensile strength on the direction of pullout strength of SFRP composites is about 3MPa~4MPa,which is low and limited to be used in strengthening and retrofitting concrete structure with low compressive strength and light loading conditions.