Mechanical Property of Beam-to-Column Connection of Steel Structures With All-Steel Buckling-Restrained Braces

To avoid brittle fracture and plastic yielding of steel beam-to-column connections under earthquakes, a new beam-to-column connection of steel structures with all-steel buckling restrained braces (BRBs) is proposed. The all-steel BRB is connected to the steel beam and column members through pins to form a new connection system. Taking the T-shaped beam-to-column connection steel structure as the research object, two structural types with an all-steel BRB installed on one side (S-type) and two sides (D-type) are considered. Theoretical equations of the connection system’s initial stiffness and yield load are derived through the mechanical models. The yield load, main strain distribution, energy dissipation, and stiffness of the connection system are investigated through quasi-static tests to verify the connection system’s seismic performance. The tests revealed that the proposed new connection system is capable of achieving a stable hysteresis behavior. At the end of loading, the beam and column members are not damaged, and the plastic deformation is concentrated in the plastic energy dissipating replaceable BRB, and the beam and column basically remain elastic. The proposed equations approximately estimated the load response of the proposed connection system. The results show that the damage mode of this new connection system under seismic loading is BRB yielding, with an elastic response from the beam-column members.

EXPERIMENTAL BEHAVIOR AND DESIGN OF RECTANGULAR CONCRETE-FILLED TUBULAR BUCKLING-RESTRAINED BRACES

This paper proposes a new design method for concrete-filled tubular buckling-restrained braces (CFT-BRBs) by incorporating the confinement effect on pre-buckling rigidity. A series of experiments are performed to investigate the effects of concrete strength and sectional dimension on the initial stiffness, ultimate strength, and energy dissipation behaviors. Experimental results indicate that the confined concrete plays an important role in the energy dissipating capacity of CFT-BRBs. On the other hand, the sectional dimensions of the steel tube and core are influential factors governing the ultimate failure modes of CFT-BRBs. The findings in study provide technical supports to optimize the design methods for ductile seismic performance of CFT-BRBs in low-rise and high-rise steel buildings.