Development and Experimental Validation of Dissipative Embedded Column Base Connections for Enhanced Seismic Performance of Steel Moment-Resisting Frames

This paper proposes a novel embedded column base (ECB) connection that defies the current paradigm in capacity-designed steel moment-resisting frames (MRFs) where column bases have been traditionally considered as nondissipative. In the proposed concept, a dissipative zone is introduced as part of the embedded portion of the steel column. This zone features a reduced cross section and is decoupled from the concrete footing with a debonding material layer. The surrounding concrete effectively restrains the embedded section against nonlinear geometric instabilities, thereby retaining simplicity in the design process. Large-scale experiments suggest that, contrary to its conventional counterpart, the proposed dissipative ECB connection exhibits a stable hysteretic response until large lateral drift demands (i.e., 7% rad). It is also demonstrated that the dissipative ECB connection is resilient to local buckling-induced axial shortening, such that it lowers the repairability needs of slender wide-flange steel columns after earthquakes. Column twisting is also minimized throughout the loading history. The results indicate that both the elastic stiffness and flexural yield strength of the proposed ECB connection can be analytically derived for potential use in engineering design. It is found that a simple nondegrading bilinear model suffices to describe the hysteretic response of the proposed ECBs for performance-based assessment of steel MRFs.