Research On Hysteretic Behavior Of Reactive Powder Concrete Filled Circular Steel Tubular Columns

With the large number of high-rise and super high-rise buildings being built and used,in order to meet the needs of lightweight,high-rise,long-span and durable civil engineering,the promotion of ultra-high strength and high performance materials and new structures is an important way to improve the seismic performance of structures and develop green buildings.Reactive Powder Concrete(RPC)has ultra-high strength,ultra-high toughness,excellent durability and environmental protection performance.RPC can work with steel pipes to form a high-performance composite structure,which has a broad application prospect in bridge engineering,hydraulic structure and protective engineering.At present,scholars at home and abroad focus on the static properties of RPC columns,and further research is needed on the hysteretic properties of RPC columns.This paper mainly focuses on the hysteretic properties of RPC column of round steel tube:(1)Three circular steel tubular RPC columns with diameters of 273 mm were designed with axial compression ratios of 0.15,0.23 and 0.3,respectively.Tests were carried out under low cyclic horizontal loads,and corresponding hysteresis curves and skeleton curves were obtained.The variation rules of bearing capacity,ductility and energy dissipation capacity of circular steel tubular RPC columns were studied.(2)The numerical model of RPC column of round steel tube was established by ABAQUS,and the steel constitutive model and the active powder concrete constitutive model suitable for RPC column of steel tube were selected.The corresponding hysteresis curve and skeleton curve were obtained by applying the same load and constraint as the test results.The results were verified with the test results.The numerical model can reflect the hysteretic properties of RPC column of round steel tube well.(3)Based on the numerical model,the influences of axial compression ratio,diameter to thickness ratio,steel yield strength,core concrete strength,hoop coefficient and slenderness ratio on hysteretic properties of RPC column of round steel tube were analyzed,and the influences of key parameters on horizontal bearing capacity,ductility,energy dissipation capacity and stiffness degradation of RPC column were revealed.A formula for calculating the horizontal bearing capacity of RPC column of round steel tube under compression and bending is proposed and verified with the experimental data,which proves the applicability of the fitting formula.(4)A numerical analysis model of single-span RPC-H-type steel beam frame with single-span circular steel tube was established,and hysteretic properties of RPC frame structure with circular steel tube were analyzed.The influences of axial compression ratio,steel yield strength,RPC strength and hoop coefficient on horizontal bearing capacity,ductility,energy dissipation capacity and stiffness degradation of RPC-H-type steel beam frame with single-span circular steel tube were revealed.