The Research Of Ultimate Bearing Capacity Under Axial Compression Of RPC-filled Steel Tube Columns

Reactive powder concrete(called RPC for short)is a new type of building material with excellent properties such as high strength,high toughness,and high durability.Inject the reactive powder concrete into steel tube to form the active powder concrete composite structure,under the action of axial compression,the resulted hoop effect can effectively improve the strength and deformation capacity of the reactive powder concrete,greatly improve its own brittleness defects,and can make full use of the superior properties of the active powder concrete,so this product has broad application prospects.Based on the experimental research on the axial compressing properties of RPC filled steel tubular columns at home and abroad,based on the existing theoretical research of the concrete filled steel tube and high-strength concrete filled steel tube,and using large-scale finite element analysis software ABAQUS,this essay studies the axial compressing ultimate bearing capacity of RPC filled steel tubular short and long columns.The main research results are as follows:(1)Based on the existing research results of the ultimate bearing capacity of ordinary concrete filled steel tube and high-strength concrete filled steel tube,the ultimate bearing capacity calculation formula of the RPC filled steel tubular short column under axial compression is derived by using the theory of limit equilibrium;it is calculated based on the stability of the long column in combination with Euler's formula,the calculation formula of the stability coefficient and ultimate bearing capacity of the RPC filled steel tubular long column under axial compression is derived.(2)A finite element model of 34 RPC filled steel tubular short columns under axial compression was established,and the accuracy of the model was verified by comparison with the existing test results;using the model calculation results,the failure modes and the loads-strain curve characteristics of typical short column under axial compression were analyzed;using the hoop index,core RPC strength and loading method as parameters in discussing their respective effects on the ultimate bearing capacity of the short column;and based on the calculation results of the model,the ultimate bearing capacity calculation formula of the RPC filled steel tubular short column under axial compression was fitted,the calculation formula is in good agreement with the experimental results in the literature through comparison.(3)A finite element model of 22 RPC filled steel tubular long columns underaxial compression was established,and the accuracy of the model was verified by comparison with the existing test results;using the model calculation results,the failure modes and the loads-strain curve characteristics of typical long column under axial compression were analyzed;the influence of the confinement coefficient and the slenderness ratio on the ultimate bearing capacity of the long column was analyzed,and based on this,the role of them on the energy dissipation capacity and deformation capacity of the long column under axial compression is discussed;according to the calculation results of the model,the calculation formula of the ultimate bearing capacity of the RPC filled steel tubular long column under axial compression was fitted.,and the calculation formula is in good agreement with the experimental results in the literature through comparison.