Numerical Simulations of Exposed Column-Base Plate Connections in Existing Steel Frames

Exposed column-base connections in existing steel moment-resisting frames are typically required to transfer simultaneously the axial and shear forces and bending moment to the foundation. This type of connection is usually both semi-rigid and partial-strength, whose behaviour may significantly affect the seismic performance of the structure. However, current code provisions provide limited guidance on the seismic assessment and retrofit of exposed column-base connections in existing frames. Therefore, further studies are needed to investigate the seismic performance of these connections, particularly considering the influence of bi-directional ground motions. To this end, this paper presents the preliminary numerical simulations of a non-seismically designed steel frame to be experimentally investigated within the ERIES-HITBASE project via bi-directional pseudo-dynamic tests. The steel frame consisted of two types of column-base plate connections, i.e., stiffened and unstiffened, representing respectively the base of moment-resisting and gravity frames. The performance of the steel frame was investigated using two finite element models for the column-base connections, supporting the design of the experimental campaign.