Study On Seismic Behavior Of Sand Concrete Beam-column Space Joint And Frame

With the acceleration of urbanization and the gradual increase of building scale,the contradiction between supply and demand of building sand is becoming increasingly prominent,and the shortage of natural river sand is in urgent need of finding alternative materials.China is rich in desert sand resources.If it can be rationally utilized,it can not only solve the problem of shortage of sand for construction,but also use local materials in areas with desert sand and save the cost of material transportation.The joints are the key parts connecting the beams,columns and slabs of concrete structures,and their seismic capacity is directly related to the safety performance of the structures under earthquake action.In this paper,the method of partial first and whole second was adopted for research.The finite element models of desert sand concrete(SRC)space node,desert sand concrete space edge node,desert sand concrete space Angle node and desert sand concrete frame were established by ABAQUS software,and the seismic performance of desert sand concrete frame system was studied.The influence of concrete materials,different joint forms,axial compression ratio and stirrup ratio on its seismic performance is studied through the structural failure phenomenon,hysteresis curve,skeleton curve and ductility performance obtained under the reciprocating displacement of each joint and frame.The research results show that the bearing capacity margin of spatial joints from yield point to ultimate point is smaller than that of planar joints because the influence of space effect on the structure is considered.However,the obtained results can better reflect the seismic performance of the joints and help to understand the bearing capacity of the joints under earthquake more truly.With the increase of axial compression ratio,the initial stiffness of spatial node,spatial edge node and spatial Angle node increases.When the reinforcement ratio of the column is increased,the yield load and ultimate load of the spatial joints,the spatial side joints and the spatial Angle joints are also increased,among which the spatial joints increase the most and the spatial side joints increase the least.When the horizontal displacement of each spatial node is small,the position of the maximum stress occurs on the side of the column and the side of the beam at the beam-column junction.With the increase of the loading displacement,the position of the maximum stress of the specimen gradually shifts to the direction of the beam end and the column end.For common sand concrete spatial joints,the yield load and ultimate load decrease with each reduction of a beam.The spatial side joints decrease by about 1% and 5%,respectively,compared with the spatial side joints,and the spatial Angle joints decrease by about 12% and 2%,respectively,compared with the spatial side joints.For the desert sand concrete spatial nodes,the yield load and ultimate load of the spatial nodes decrease with each less beam,and the spatial edge node,spatial in-space node and spatial Angle node decrease by nearly 4% successively.The bearing capacity of common concrete joints decreases faster than that of desert sand concrete joints after reaching the ultimate load due to the difference between sand sand and common sand.In the frame research,the initial stiffness of the frame increases with the increase of axial compression ratio.The yield load of the structure decreases by about 1.5% and the limit load increases by about 2% when the hoop ratio increases by one grade.The failure position of desert sand concrete frame under earthquake action is concentrated at the junction of column foot and beam column.With the increase of displacement,the maximum stress at the bottom of column gradually transfers to the top of column,and the maximum stress at the end of beam gradually transfers to the middle span.When the frame reaches the ultimate load,the bearing capacity of concrete frame with sand and desert sand has little influence on the difference between sand and common sand.Based on the research conclusion of three kinds of joints and one frame model,the seismic performance of desert sand concrete joint is similar to that of common sand concrete joint,so it can be considered as an alternative material of common sand concrete.