Improving seismic performance of fully welded connection based on truss beam segments

Abstract

To enhance the seismic performance of fully welded connections (FWCs), the addition of truss beam segments to the upper and lower beam-end flanges has been investigated. This study focuses on two 2/3-scale cross-shaped substructures with an FWC and a fully welded connection with truss beam segments (FWCT). Through cyclic loading tests and detailed numerical simulations, the failure mode, hysteretic behavior, bearing capacity, ductility, strength and stiffness degradation, and energy dissipation capacity have been investigated. The results show that local cracks first appeared in the concrete slab around the column of the FWC specimen and that the lower flange at the beam root fractured eventually. Regarding the FWCT specimen, when the joint zone satisfies the shear strength requirement, a plastic hinge is formed at the beam end instead of in the joint zone, and the plastic hinge at the beam root propagates outward before eventually breaking at the beam flange. The hysteretic curves of both FWC and FWCT specimens present a spindle shape, whereas that of the FWCT specimen shows a fuller shape. The seismic performance of the FWC specimen is improved significantly by the truss beam segments. The initial stiffness, yield load, yield displacement, peak load, peak displacement, ductility coefficient, and cumulative total energy dissipation increased by 8.91%, 12.50%, 13.07%, 13.41%, 20.32%, 36.73%, and 138.53%, respectively. After the beam flange yielded, the truss beam segment and beam flange cooperated in terms of deformation and energy dissipation. When the beam flange failed, the truss beam segment continues to bear the load.