Experimental research on seismic behavior of flush endplate composite joints under reciprocating bending load with constant axial force

Only bending moment and shear force at beam end are commonly considered in designing beam-to-column connections. However, axial force at beam end has to be taken into account in some cases. Four flush endplate composite connections between steel-concrete beam and steel column were designed, fabricated, and tested. The specimens were subjected to reverse bending under separately no axial force, 10% of N_by tension force, 20% of N_by tension force and 10% of N_by compression force at beam end. The seismic behaviors, such as stiffness, bearing capacity, ductility, hysteretic behavior, energy dissipation capacity and failure modes, etc., were studied. The results indicate that beam end axial tension force can intensify the deformation and damage of the specimens, and reduce the bearing capacity, stiffness and energy dissipation capacity and so on; however, the compressive force can delay the deformation and damage of connections in early stage, and accelerates the damage of specimen as the deformation increasing; regardless of the beam end force is axial tension or compression, the ductility of the specimens are significantly decreased, and the total energy dissipation capacity declines.