Column Base Connections: Research, Design, and a Look to the Future

Abstract

Column base connections are critical to the performance of steel structures, serving as the interface between the steel superstructure and concrete foundation. Historically under-researched, these connections have received significant attention over the past two decades, leading to major advances in understanding their strength, stiffness, seismic behavior, and simulation. This paper provides a synthesis of these developments, focusing on exposed and embedded base connections across a range of loading conditions and structural configurations. Key contributions include improved strength models, detailed assessments of seismic performance, and the introduction of modeling tools now included in the 3rd Edition of AISC Design Guide 1. The paper discusses elastic and inelastic behavior, base connection–frame interaction, and the emerging use of base connections as yielding elements in seismic design. Advances in simulation of base connections, including rotational spring and line-element-based models, enable more accurate structural simulations. Despite this progress, notable gaps remain, including the behavior of braced frame connections, foundation-soil interaction, and performance-based design for repairability and resilience. This work aims to consolidate recent findings, inform ongoing research, and guide future design practices toward a more integrated treatment of base connections in steel structures.