| A post-tensioned (PT) column base connection is introduced for use in a self-centering (i.e., returns to its original position after earthquakes) steel moment resisting frames (SC-MRF). The PT column base connection eliminates inelastic deformation in columns, and enhances self-centering capability of the SC-MRF. The PT column base connection consists of high strength bars that are post-tensioned and buckling restrained steel (BRS) plates. Under cyclic loading, the softening behavior at the connection is achieved by gap opening at the column-beam interface instead of plastic hinging of the column. The PT bars provide restoring force for self-centering behavior while the BRS plates dissipate energy by yielding.;To investigate the cyclic behavior of the PT column base connections, a series of the PT column base connection subassemblies were subjected to axial load and cyclic lateral displacements. Test variables included initial post-tension force, initial axial force in column (constant or varying), column size and loading history. Main findings include: (1) the column returns to its original position without residual deformation and (2) the BRS plates dissipate energy by yielding in tension and compression.;Design criteria for the PT column base connections were developed along with design equations. Also, analytical models of the PT column base connections were developed. Finally, the seismic behavior of a prototype 6-story, 4-bay SC-MRF with PT column base connections was evaluated by nonlinear dynamic analyses for various ground motions. |
