Experimental Study On Frame Joints Between Concrete -filled Steel Tubular Core Columns And Prestressed Concrete Beams Under Reversed Cyclic Loads

The concrete-filled steel tubular core column, which is a new type of member, has been proposed to be applied to prestressed concrete frames in this paper. In the frames concrete-filled steel tubular columns intersect beams at joints. The joints synthesize advantages both of concrete-filled steel tubular core columns and of prestressed concrete beams. This paper attempts to research the seismic behavior of joints between concrete-filled steel tubular core columns and prestressed concrete beams under reversed cyclic loads, in order to make the joints become a good kind of seismic system. Five specimens have been designed and tested, among which four specimens are frame joints between concrete-filled steel tubular core columns and prestressed concrete beams and one specimen that is a contrast is a joint between a reinforced concrete column and a prestressed concrete beam. Based on the experimental results , the mechanical behavior and the failure modes of specimens under reversed cyclic loads have beeb depicted, the principal indexes of strength, the stiffness of joints, the ductility and the energy dissipation have beenanalyzed. The influences of the steel tubes on the failure modes of specimens, on the shear strength of core area of joints, on the stiffness of joints, on the ductility and on the energy dissipation. Meanwhile, both the function of concrete-filled steel tubular core columns in raising aseismic strength and the hysteretic behavior of joints specimens have been studied. In addition, the failure modes , the strength, stiffness, the ductility and the energy dissipation of the joints between concrete-filled steel tubular core columns and prestressed concrete beams, of have compared with those of the joint between a reinforced concrete column and a prestressed concrete beam. Based on the results of experimental research, we can find that the construction method of joints zone are feasible and safe, the joints between concrete-filled steel tubular core columns and prestressed concrete beams have good ductility and good energy dissipation, and the concrete-filled steel tubular core columns can raise the shear strength of core area of joints and the bending strength of the column ends.