Axial Compressive Behavior Of Preplaced Aggregate Concrete-filled Circular Steel Stub Columns

Compared with traditional concrete,Preplaced Aggregate Concrete has a high content of coarse aggregate.It is in a state of close packing,which fully exerts the skeleton action and aggregate interlocking effect of coarse aggregate.Moreover,it has the characteristics of less amount of cementing material,low energy consumption,low shrinkage of concrete,and strong durability.Combining the characteristics of the preset aggregate concrete with the concrete-filled steel tube structure,on the one hand,the characteristics of the preset aggregate concrete and the advantages of the concrete-filled steel tube structure can be exerted,and on the other hand,the shrinkage and creep of the concrete in the concrete-filled steel tube structure can be solved.There are shortcomings such as empty drums and high energy consumption,and the engineering value and social benefits are remarkable.To study the axial compression performance of the steel pipe-preset aggregate concrete column,firstly,based on the previous research,the paper determined the preparation process of steel pipe-preset aggregate concrete column and the static force of preset aggregate concrete.The performance of the system was studied systematically,and the influencing factors of the mechanical properties of the preset aggregate concrete were obtained.The general law of the stress-strain curve of the preset aggregate concrete was obtained.Secondly,the paper designed seven steel pipe-preset aggregate concrete short columns and three ordinary steel pipe-preset aggregate concrete short columns.Through the axial compression test,the steel pipe-preset aggregate concrete short column and ordinary steel pipe were obtained.The mechanical properties of the short concrete columns are different from those of the joints,and the mechanical influence factors of the preset aggregate concrete short columns are explored.Based on this,the nonlinear finite element model is established by ABAQUS software and the variable parameters are analyzed.The corresponding relationship between the steel pipe-preset aggregate concrete column and various influencing factors is obtained.Finally,the paper combines the current design rules of concrete-filled steel tubular columns,and deduces the calculation method of steel-preset aggregate concrete columns,and obtains the design method of steel-preset aggregate concrete short columns.Through experimental research and finite element analysis,it is shown that the round steel pipe-preset aggregate concrete short column is equivalent to the ordinary circular steel tube concrete short column,which has relatively high ultimate bearing capacity and higher deformation capacity,and saves 20% of cement.The amount and energy consumption can meet the requirements of factory production of pre-assembled components.