The Analysis of Mechanical Behavior of Special Concentrically Braced Single-Story Frames With Ductile Casting Steel Connectors

The special concentrically braced frame (SCBF) is an aseismic structure, but its bracing system exhibits brittle failure and premature buckling connected with the weld fracture of the gusset plate and the post-buckling of the braces; thus, maximizing the role of energy dissipation is difficult.

Here, this paper proposes a system of special concentrically braced single-story frames with ductile casting steel connectors. The large inelastic deformation of the bracing system is mainly concentrated in the ductile casting connectors under the earthquake, and the degree of buckling can be reduced. The finite element model of a single-story frame with special central support and casting steel connectors was established by ABAQUS. Monodirectional loading simulations were conducted on 12 groups of specimens with different parameters, then the deformation trend, stress distribution, initial stiffness, and ductility of the specimens were analyzed.

The seismic behavior of the frames was evaluated by the variable parameters of the width-thickness ratio of the energy dissipation plate and stiffener, the length of the energy dissipation segment of the casting connectors and the overstrength coefficient. The casting steel connector conducts the main connectors that exhibit good ductile and initial stiffness.

The study results provided direct evidence that the seismic performance of specimens is closely associated with the length of the energy dissipation segment of the casting connector and the overstrength coefficient of axial force. Also, the stress distribution, initial stiffness, and ductility of the members can be independently controlled by reasonably designing the casting connector.