Experimental Study On Seismic Performance Of Shear Walls Reinforced With MRPC Surfac

Shear wall structure is one of the main structural forms of existing buildings.As the first line of anti-seismic fortification,shear wall is the main lateral force component under earthquake action.At present,the existing volume of shear wall structures in our country is huge,and will be growing in the future.Due to the influence of environmental and human factors,some shear wall structures appear the phenomenon of local aging damage.This part of shear wall can not meet the requirements of seismic fortification,which leads to the safety problem of building structure becoming increasingly prominent.If the shear wall structure is damaged,it will cause huge economic losses and casualties,so the detection and reinforcement of the existing low strength shear wall is worth studying.In response to the above issues,this article adopts Modified Reactive Powder Concrete(MRPC)surface layer to reinforce low strength shear walls,in order to provide new methods and ideas for the field of shear wall reinforcement.In this thesis,a low-cycle repeated load test was carried out on one shear wall in the control group and three shear walls in the experimental group with different reinforcement methods,and the effects of single-sided reinforcement,double-sided reinforcement and different surface thickness on the failure mode of the wall were studied.The differences in bearing capacity,hysteretic characteristics,ductility and energy dissipation of various shear walls under the influence of different factors were analyzed.The finite element simulation analysis was carried out on the test,and the similarities and differences between the test results and the simulation results were compared.The main conclusions of this paper are as follows:(1)The failure modes of all four shear walls are bending failure,and the development range of cracks is concentrated in the middle and lower parts of the wall,with horizontal cracks at the bottom and oblique cracks at the middle.The main failure signs of each shear wall are the crushing and falling off of concrete in the corner on both sides,and the fracture of steel bars in the hidden column.(2)After strengthening by MRPC surface layer,the bearing capacity and seismic performance of the shear wall in the experimental group are significantly improved,which can reach or even exceed the level of the control group.There is a good bonding ability between MRPC surface and internal concrete,especially in the middle and late stage of loading.The PP fiber and steel fiber in MRPC can effectively inhibit the crack widening and development in the later stage of loading,indicating that the way of surface layer reinforcement can give full play to the advantages of high strength and good ductility of MRPC material to a greater extent.(3)Under the same surface thickness,double-sided reinforcement is better than single-side reinforcement.Simply increasing the surface thickness can not enhance the reinforcement effect.The test shows that the specimen SW-2 is a relatively good reinforcement method.After adopting this reinforcement method,the load borne by the shear wall at all stages exceeds the level of the control group,the ductility and energy dissipation capacity of the wall are significantly improved,and the ductility coefficient of the specimen is increased by about 21%.(4)By calculating the flexural bearing capacity of the normal section of each specimen,the calculation formula of the flexural bearing capacity suitable for the MRPC surface layer reinforced shear wall is obtained,and the calculated value is in good agreement with the experimental value,which can provide a theoretical basis for practical engineering.(5)By using ABAQUS finite element software to simulate this test,the tensile damage diagram obtained is compared with the test results,and it can be found that the crack trend,development form and crack distribution area are almost the same,which indicates that the failure mode of shear wall is bending failure.In addition,the skeleton curve obtained by simulation is basically consistent with the experimental results,which proves that the finite element model established can reflect the mechanical properties of shear wall specimens to some extent.