| RCS composite frame, composed of reinforced concrete column and steel beam, is a newly low cost and highly efficient structure for its economical utilization on the characteristic of steel and reinforced concrete. In this paper, 3 interior joints of through beam RCS composite frame with high shear-compression ration is designed. Mainly used detailing measures include: horizontal stirrups set in joints, face bearing plate installed beside joints, part of longitudinal reinforcements welded in holes of steel beam's flange, set steel erection column and stirrups appended around joint. Base on the cyclic loading tests and relative analysis of the 3 spencimens under different loading conditions (axial force ratio, the characteristic value of the stirrup in the joint ), these conclusions can be made: ①When steel beam yields to make plastic hinge appear , and after which joint is failed by shear, joints of RCS frame have high strength, good ductility and strong energy comsumption ability. ②The regularity of seismic performance of the through beam RCS frame joint can be summarized into "3 level and 4 mechanisms": level 1, "frame-shear wall"mechanism formed by steel section composed of through-joint girder's web and flange. level 2, diagonal strut mechanism formed by inner joint core concrete within the flange width. level 3, struss mechanism and diagonal strut mechanism formed by exterior joint core concrete out of the flange width. lever l is the most active one, level 2 takes part in action through lever 1, and level 3 is the most passive, which takes part in the action through the level 2. ③When steel beam yields to make plastic hinge appear , and after which joint is failed by shear,there is no need to require too high of the stirrup's minimum reinforcement ratio. ④Increasing axial force ratio can improve the crack load and early rigidity, but if too high, shear ability of girder web in the joint core will reduce, burden of diagonal strut will enhance and ductility of beam-column joint of RCS frame will fall. ⑤The detailing measures take great affection on the RCS joint performance. And the detailing measures in this paper can avoid the early vertical bearing failure. ⑥Based on the current seismic shear design formula of the joint between steel-reinforced concrete column and steel beam, and combined with the experimental data and analysis, this paper suggests the calculation expression of the seismic shear resistance of the RCS composite frame.
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