The use of post-tensioning to reduce seismic damage in steel frames

A post-tensioned friction damped connection for earthquake resistant steel moment resisting frames (MRFs) is introduced. The connection includes friction devices with post-tensioned high strength strands running parallel to the beam. The connection has excellent ductility, minimizes inelastic deformation to the components of the connection, requires no field welding, and returns the structure to its pre-earthquake position. Inelastic analyses were performed on a 6-story, 4-bay post-tensioned steel MRF to study its response to strong ground motions. Results show good energy dissipation, strength, and ductility in the post-tensioned system. The analyses indicate that the seismic performance of a post-tensioned steel frame can exceed that of a frame with conventional moment resisting connections.