Seismic Performance Of Masonry Wall Retrofitted With CFRP Grid

Fiber reinforced polymer(FRP),as a kind of composite material due to its lightweight,high strength,good durability and so on,has been widely used in the reinforcement and repair of existing and new buildings in recent years.For the researches on the seismic performance of the masonry walls strengthening with FRP at home and abroad,it mainly adopted the technology of sticking the FRP plate or sheet outside.But the anisotropic characteristic of FRP sheet which shows low tensile strength at the direction of no fiber,so CFRP grid has bi-directional fibers leading to the further enhancement in seismic performance,in addition,the unique mechanism chain of which further improves the performance of retrofitted walls.The available papers showed that bond behavior of the FRP-concrete/brick interface is a key factor for transferring stress the bonding interface.The failure of reinforced walls caused by the debonding of the FRP mostly occurs,so it should take some effective anchor measures to prevent the debonding and buckling of FRP.Aiming at the region of FRP retrofitted masonry walls which needs to improve,combining the experimental research with theoretical analysis,study the related issues of FRP grid strengthening masonry walls,mainly including the following aspects:(1)Seismic performance of multi-storey masonry wall with opening repaired using CFRP grid.This study introduced an experimental study on the seismic performance of multi-storey masonry wall with opening repaired using CFRP grid.A 1/3 scale three floor masonry wall with opening was firstly tested under pseudo-static action to simulate the seismic damages.The damaged masonry wall was then repaired by externally bonding CFRP grid to the areas where the cracks severely occurred according to its failure mode and damage mechanism.The repaired masonry wall was retested under the same loading to evaluate its seismic resistance and assess the recovery contributed from the CFRP grid.The CFRP grid can effectively postpone or even prevent the occurrence and development of cracking.The seismic shear capacity of masonry wall can be restored by appropriate CFRP grid strengthening schemes.The seismic resistance of masonry,including ductility,energy dissipation and deformability,was dramatically restored or even promoted.The preliminary minimum strengthening scheme and design recommendation for the similar structures were eventually proposed in accordance with the findings of this work.(2)Research on seismic performance of masonry walls reinforced with a hybrid CFRP grid-anchors system.This study introduced an experimental study on the seismic performance of masonry walls strengthening with CFRP grid.9 masonry walls were designed to test under pseudo-static action to subject,including one unreinforced masonry wall and four different types of reinforced walls.By studying the failure mode and some detailed seismic indexes,the test result showed that CFRP grid can effectively postpone or even prevent the occurrence and development of cracking,meanwhile the anchors obviously restricted the debonding of the CFRP grid.The seismic resistance of masonry walls,including shear capacity,energy dissipation,deformation capacity,stiffness degradation and ductility,was dramatically enhanced.The design recommendation for the similar structures was eventually proposed in accordance with the findings of this work.(3)Based on the experimental study,the design formula of seismic shear bearing capacity of the masonry wall reinforced with CFRP grid was proposed.Through the comparison and assessment of the existing models proposed by the others,considering the characteristic of FRP grid,set up a new model which is applicable to the seismic shear bearing capacity of FRP reinforced masonry walls with “X” diagonal configuration.