| Reinforced concrete column-steel beam(RCS)frame structure is a kind of hybrid structure which is made up of steel and concrete,and it combines the advantages of traditional reinforced concrete structure and steel structure.The RCS frame can make full use of high bearing capacity of concrete and high ductility of the steel,which perform an outstanding response under earthquake.This kind of structure meet the requirements of the development of modern civil engineering and have broad prospects.On the other hand,beam-column joint is the key part of the whole frame structure,because it is subjected to axial load,bending and shear from composite stress state,so it is vital to the security of the whole frame.In this paper,36 FE models of precast high-strength concrete tube column and steel beam frame were carried out by using ABAQUS to analyze many parameters such as axial compression ratio,reinforcement ratio including non-prestressed reinforcement,stirrup ratio,prestressed tension,line stiffness ratio,infilling tube column,Length of embedded steel pipe,width and thickness of annular plates.FEA results show the following signals:(1)With the increase of axial compression ratio,the seismic performance of the specimen decreased gradually.(2)Prestressed reinforcement can effectively improve the bearing capacity of the specimen,but the larger of the tensile strength,the initial stiffness is larger,and the bearing capacity decreased rapidly later.(3)The length of the embedded steel pipe and the width of the annular plates is not obvious to the seismic performance of the specimens.According to the previous finite element analysis structure,the paper designed and produced 6 precast high-strength concrete tube column-steel beam hybrid frame joints with the anti-seismic design construction measures as followings:(1)The width of the annular plates is 60 mm,with the thickness setting two kinds of 10 mm and 16mm;(2)The length of the embedded steel pipe is 400 mm,with the thickness 10mm;(3)Anti shear structural measures use shear studs and welded reinforcement to make contrast.(4)The construction measures of the tube columns are different from whether filling concrete and types of hoop reinforcement.Six RCS hybrid joints specimens were tested under cyclic loading under the same axial compression ratio(0.15),and after the data analysis the main 4 conclusions are as follows:(1)There is no damage to the core area of the joints of the six specimens.The earthquake resistance design concept of strong connection and weak member can be achieved.The two anti-shear structural measures –shear studs and welded reinforcement can ensure the effective transfer of beam shear and have little effect on the seismic performance.(2)The specimen JD-1 performed a beam hinge failure mode,and the hysteretic curves show a relatively regular “Spindle”,it has excellent energy absorption capacity with the equivalent viscous damping coefficient is 0.25.The other specimens performed column hinge failure mode with the pinch phenomenon existing on the hysteresis curve and the.equivalent viscous damping coefficient spread from 0.12~0.18.(3)During the whole loading process,stiffness degradation is plentitude and there are no stiffness mutation because of the existing prestressed reinforcement.Composite Stirrups can effectively improve strength and ductility from the data of JD-2 and JD-5.But filling concrete has little effect to the strength of the joints(4)The outer enforced loop plane itself is not obvious in the effect of horizontal force transmission,but on the other hand it can ensure the transmission through the embedded steel pipe. |
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