Primarily engineered to resist gravity-induced shear forces, beam-to-column connectors must also withstand significant lateral deformations and rotations during earthquakes. In seismic design, natural period, stiffness, damping, and ductility represent the essential structural properties to be considered. Determining a structure’s fundamental period is crucial for estimating its design base shear force and acceleration response—two principal factors influencing safety and resilience. An increase in connection stiffness leads to a greater design base shear force, with a disproportionate reduction in lateral drift. Additionally, heightened stiffness corresponds to a more pronounced acceleration response, potentially causing more structural and non-structural damage. Thus, an excessively stiff connection may not be ideal for mitigating dynamic loading. An optimal structural design should minimize the acceleration response and associated base shear force while allowing acceptable lateral deformation.

This white paper—which supplements a previously published white paper—presents results from a series of monotonic and cyclic pushover experiments performed at Oregon State University (OSU), examining the drift performance of three different connections in terms of stiffness and damping capacity.