| CFRP grid-polymer cement mortar(PCM)reinforced concrete structure is a new technology of structural reinforcement that has emerged in China in recent years.Compared with the traditional method of building structure reinforcement,it has the advantages of light weight,high strength,simple construction,and can be used in the construction of harsh environment,and the application prospect is very wide.Similar to the FRP-concrete structure,ensuring sufficient bonding strength at the interface is the key to the expected performance of CFRP grid-PCM reinforcement technology.However,due to the late start of domestic research on this technology,the interface mechanical properties of CFRP grid-PCM reinforced concrete structures have not yet been fully clarified.Based on this,this paper uses the finite element software ABAQUS to simulate the interface mechanical properties of CFRP grid-PCM reinforced concrete structures,so as to reveal the interface failure mechanism and interface behavior deeply,and provide theoretical basis and design suggestions for the application of this reinforcement technology in concrete structures.The specific research results are as follows:(1)According to the mechanical properties and interaction of the pull-out specimen materials,a simplified mechanical model of the interface between CFRP grid-PCM and concrete was proposed.Based on this,a two-dimensional numerical model was established and analyzed to obtain the ultimate load and vertical strain of the specimen.Compared with the actual test results,the rationality of the simplified mechanical model is verified.Through the change of strain and strain difference under the grid point,the transfer law of interfacial stress during the process of loading is analyzed.(2)The grid spring model was proposed for the lattice point force behavior in CFRP grids,which was applied to the finite element simulation analysis of grid pull-out test specimens,including two cases divided by considering vertical bar bonding or not.By calculating the strain difference of the grid point,the force of the grid point,and the bearing ratio,etc.,the stress performance and failure of the grid point during the loading are analyzed,and the minimum number of grid points corresponding to the use of the grid bars in different grid point pull-out pieces is obtained.In addition,combined with the characteristics of the grid forces during the process of loading,the multi-grid bearing mode and grid anchoring effect in CFRP grids are analyzed.(3)More detailed simulations of the CFRP grid-PCM and concrete interface failure were carried out,and finite element model were established based on the different failure forms of the pull-out specimens.The cohesive interface element is used to simulate the peeling failure between the CFRP grid-PCM and concrete,and the influence of changing the interface element parameters on the bearing capacity of the pull-out specimens is analyzed.The CFRP grid pull-out failure finite element model considering the mechanical properties of the grid was established.The grid point failure analysis is carried out according to the grid point stress and strain sharing rate,and the influence of different factors on PCM cracking performance is analyzed according to equivalent plastic strain and cracking influence coefficient.(4)Combined with the finite element calculation results,the stress distribution and transfer mechanism at the interface of the pull-out specimen are revealed from the perspective of theoretical analysis,and the interface failure process of the pull-out specimen is analyzed.A theoretical analysis model based on failure form is proposed to further clarify the interface failure mechanism of CFRP grid-PCM and concrete,providing theoretical basis for practical engineering application,and corresponding suggestions and measures are given. |
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