The DuraFuse Frames connection is a field-bolted connection with a replaceable fuse plate below the beam bottom flange. The fundamental seismic behaviors expected with the DuraFuse Frames connection include:
- (1) Shear yielding in particular regions of the replaceable fuse plate, followed by strain hardening at larger deformations.
- (2) Slip of the fuse plate bolts and top plate bolts, which occurs at a similar resistance level to the initial yielding.
The combination of bolt slip and fuse plate yielding results in large inelastic deformation capacity for the DuraFuse Frames connection while preventing yielding in the beam and column.
Prequalification of the DuraFuse Frames connection is based on full-scale tests performed in accordance with AISC Seismic Provisions Chapter K (AISC, 2016a). Ten qualifying tests were performed on connections with beams ranging in depth from W21 to W40 at the University of California, San Diego (Reynolds and Uang, 2018; Reynolds and Uang, 2019). The deformation capacity varied depending on the depth of the beams, and ranged from 0.04 rad to 0.08 rad, with shallower beams having greater capacity. I-shaped and box columns were included in the testing program. Eight other full-scale qualifying tests are reported in Richards and Oh (2018). For reference, reduced scale prototype tests are reported in Richards and Oh (2019).
The stiffness of the DuraFuse Frames connection is sufficient to be considered fully restrained (FR). The stiffness of experiments and finite element models have been compared with the stiffness of 2D centerline models where the flexibility of the panel zone is explicitly considered and the connection is replaced by a rotational spring with a stiffness of . The experimental and FE stiffness have been equal to or greater than that of the centerline models, justifying the classification as a fully rigid (FR) connection.