Seismic Performance Of A Hybrid FRP Grid-anchor System Strengthening Masonry Wall

Fiber reinforced polymer(FRP)has been widely used in masonry structure strengthening and repairing.However,the permature FRP debonding failure greatly limits the strength of FRP.Appropriate anchors can effectively delay or even prevent the occurrence of debonding failure and eventually improve the strengthening performance.In addition,due to the anisotropic characteristics of FRP material,the strength and ultimate strain of non-fiber direction are very low.FRP grid has bidirectional fiber,which can solve this problem well,and it performs a superior performance when strengthening a structural memeber with large area,such as,masoney walls.Based on the these background,this thesis combines the experimental research and theoretical analysis to study the related issues of a hybrid FRP grid-anchor system strengthening masonry wall,mainly including the following aspects:(1)Experimental study on anchorage performance of FRP anchor.36 specimens from12 groups were drawn out according to the production method,the diameter of the hole,the depth of burial and the fabric width.The results showed that: the pre impregnated folding FRP anchor shows an excellent performance of both manufacture processing and anchorage performance than the other FRP anchors.The predrilled hole diameter and the width of the FRP sheet and the anchoring strength are nonlinear,the relation between the depth of predrilled hole and the anchorage strength is linear.(2)Anchorage mechanism analysis and pull out capacity model of FRP anchor in masonry were proposed.Through analyzing the anchorage mechanism of postembeddment anchor in concrete and the results of pull-out test,getting the anchoring mechanism of fiber anchor in clay brick and the relevant parameters which influence on the anchorage strength.By modifying the pull out capacity model for concrete,gets the pull out capacity model for the FRP anchor embedded in masonry.Comparing the results from the proposed models and the experimental results,it shows that the proposed models deliver good agreement.(3)Experimental study on a hybrid FRP grid-anchor system strengthening masonry wall.3 pieces of masonry walls were designed according to the conclusions of the previous research,which were unstrengthened masonry wall,sole FRP grid strengthening and hybrid FRP grid-anchor system strengthening.Three masonry walls were tested under low cyclic loading to study the bearing capacity,failure mode,hysteretic behavior,stiffness degradation and so on.The results showed that walls being strengthed by FRP grid or FRP grid-anchor hehave a improved seismic performance bearing capacity and ductility have been obviously improved.For the The wall that was reinforcedbeing strengthened by using FRP mesh and FRP anchora hybrid FRP grid-anchor system,the appearance of anchor is effective in delaying debonding failure,the ductility of wall has been further improved.