This paper explores the concept of dissipative exposed column base connections by means of anchor rod yielding. This concept aims at enhancing the seismic performance of low-rise steel moment-resisting frames (MRFs). A mechanics-based model is proposed that explicitly simulates a broad range of damage mechanisms observed in exposed column bases. The model is implemented in a frame finite element analysis program and its hysteretic performance is validated with experimental data available in literature. Incorporating this modeling feature in standard nonlinear response history analyses offers new insights in steel MRF responses. It is shown that when low-rise steel MRFs adopt a dissipative anchor-yield column base concept, they are less likely to experience residual story drift ratios during low-probability of occurrence seismic events. It is also found that low-rise steel MRFs designed with non-dissipative exposed column base connections are more prone to demolition than dissipative ones, due to their higher column residual axial shortening, particularly when ground motion duration is an important feature of the seismic hazard. Limitations of the present work are also discussed.

Summary This paper proposes methodological developments for quantifying the impact of residual axial shortening of first‐story steel columns on earthquake loss estimations in steel moment‐resisting frame (MRF) buildings. A new formulation is proposed that accounts for the likelihood of having to demolish a steel MRF building due to column residual axial deformations in addition to residual story‐drift ratios. The formulation is informed by means of data from a comprehensive survey conducted worldwide to assess the likelihood of steel column repairability due to residual axial shortening. A practical method for quantifying column axial‐shortening in parameterized system‐level numerical simulations is presented. The proposed approach is illustrated by conducting economic seismic loss estimations in two case‐study steel MRF buildings designed in urban California according to the current seismic design practice. It is found that when the ground‐motion duration is appreciable, the examined steel MRFs are more prone to column axial‐shortening than residual story‐drifts at moderate to high seismic intensities. The results suggest that economic losses due to demolition may be underestimated if column residual axial‐shortening is neglected from loss estimations. Limitations as well as directions for future research are discussed.