Low-Slip Force Friction Connections for Early Phase Energy Dissipation in Steel Structures

Abstract

Previous research suggests adding early phase energy dissipation to structural steel systems can improve seismic performance. This can be achieved with a Low-slip Force Friction (LSFF) damper designed to activate prior to yielding of the seismic force resisting system. A friction device included in the simple gravity frame connections of a steel structure provides an economical mechanism for inducing early phase energy dissipation. This simple device can be installed in any steel structure as part of a conventional seismic-force resisting system, a performance-based seismic protective system, or the seismic rehabilitation of an existing structure. This connection will improve performance for structures during short return period earthquakes when few other lateral force resisting elements dissipate energy. The device will remain active during large events improving the response of buildings which have already demonstrated reliable performance for design and maximum considered events. This thesis will show the effects of early phase friction energy dissipation through nonlinear dynamic analysis of three and nine story structures designed with Special Moment Resisting Frames (SMRF) and Buckling-Restrained Brace (BRB) frames. A suite of earthquakes scaled to the hazard spectrum at four return-periods is used for the dynamic analyses. The comparison between baseline code-designed BRB and moment frames to those with early phase dissipation includes drift, acceleration, and ductility related metrics. Variations of friction device configurations are investigated including number, distribution, and slip force. This research provides the foundation to understanding a LSFF system and how steel structures can be designed to provide more resilient, sustainable, and reliable infrastructure over a wide range of return periods without a significant construction or engineering cost increase.