Performance assessment of self-centering structures equipped with a novel double-slip load friction damper

In this study, a novel double-slip load friction damper (DSL-FD) incorporating composite friction pads is proposed. The damper employs a separate bearing connection to enable a controlled transition between two stages of slippage. Finite element analyses conducted using Abaqus confirm that the DSL-FD exhibits fully elastic behavior. Experimental tests demonstrate stable hysteretic performance and a distinct transition between the two stages of slippage, with no plastic deformation observed in the steel components. The double-level slippage behavior of the DSL-FD reduces the re-centering force required to achieve self-centering (SC) behavior in structures. Accordingly, the application of DSL-FDs in SC structures is proposed. Comparative nonlinear time-history analyses are performed on 8-, 12-, and 16-story three-dimensional (3D) steel moment-resisting frames (MRFs), including SC-MRFs equipped with DSL-FDs, non-SC MRFs equipped with DSL-FDs, and non-SC MRFs equipped with single-slip load friction dampers (SSL-FDs), subjected to near-field and far-field ground motions. The results indicate that SC-MRFs equipped with DSL-FDs perform effectively, achieving substantial reductions in residual drift ratios (below 0.1% of the story height) compared with non-SC MRFs equipped with either the SSL-FDs or the DSL-FDs. Moreover, DSL-FD reduces the required re-centering force to as low as one-fifth of its second-level slippage force.