A New Prefabricated Shotcrete Sandwich Wall System

The 19 th National Congress of the Communist Party of China put forward the strategy of rural revitalization,with its primary goal of ensuring the construction of rural livable houses and other infrastructure.At present,however,most of rural houses are mainly traditional masonry structures with poor seismic performance and low heat-insulation performance,which can not meet the livable requirements for rural houses.The traditional cast-in-place concrete structure and prefabricated structure,whose construction method and economical efficiency are far beyond the rural demand and bearing capacity,so it is difficult to be applied in rural and remote areas.Therefore,this study combines the advantages of existing steel-wire panel and prefabricated shear wall,and proposes a new type of steel-wire mesh sandwich wallboard integrating load-bearing,heat preservation and thermal insulation.The combination of the built-in wire mesh and shotcrete technology applied in the side wall of the new type of fabricated wall enhance the construction efficiency of the wallboard,and the filling core materials of the wall is foam concrete with the functions of thermal insulation and inner framework.In order to analyze the mechanical properties of the new type of fabricated shotcrete sandwich wall,this paper made six specimens of it by shotcrete technology,carried out axial compress test on three specimens of the sandwich wall,and conducted the quasi-static test on other three specimens.The results of compression test show that the main failure modes of the new type of fabricated shotcrete sandwich wall under load are mainly compression failure and out-of-plane deformation failure of shotcrete surface.The integrity of the wall is good,in which the concealed column and shotcrete surface,as well as the longitudinal bar and bottom connecting reinforcement of the concealed column can work together to bear the compression.In a certain range,the compression bearing capacity and axial stiffness of the sandwich wall increase with the decreasing of the height-thickness ratio and the height-width ratio,especially the height-width ratio has a great impact on compression bearing capacity.The construction quality of shotcrete also has a significant influence on the failure mode and bearing capacity of the specimens.The existence of eccentric distance leads to the uneven development of stress and vertical displacement of shotcrete surface and concealed column onboth sides of the wall,which reduces the ultimate bearing capacity of the wall.According to the stress features of the wall,the static distribution superposition method can be used to calculate the bearing capacity of the normal section of the wall.The combination of the analysis of the mature calculation theory of the axial compressive and eccentric compressive capacity of the sandwich wall at home and abroad with the characteristics of the new type of shotcrete sandwich wall improved the equation and propose the axial compressive and eccentric compressive capacity calculation formula of the normal section of the new type shotcrete sandwich wall.The quasi-static test results show that as a whole,the concrete layers and inner columns of the new type fabricated shotcrete sandwich wall can work together to resist both vertical and horizontal forces.Under the premise of the construction quality of shotcrete surface,the perps between the wall and edge members are connected reliably.Under the low frequency cyclic loading,the overall performance of the sandwich wall is bending and shearing failure modes.The drift ratio at ultimate of the specimen is bigger than 1/120,and the nonlinear distortion capability and plastic energy dissipation capacity meet the seismic requirements.The vertical reinforcement and the bottom connecting reinforcement bar in the concealed column of the specimen can also bear the load together,and the connection performance is good.Based on the analysis and comparison of current concrete design codes at home and abroad,the shear capacity formula of obligue section suitable for shotcrete sandwich wall is obtained by considering the specimen as shear wall and common shear member.