Seismic Performance of a Steel Self-Centering Moment Resisting Frame System with Beam Web Friction Devices
ATLSS Report No. 12-06:
The behavior of a self-centering moment resisting frame (SC-MRF) is characterized by connection gap opening and closing at the beam-to-column interfaces. An SC-MRF uses horizontally-oriented high strength post-tensioning (PT) strands to precompress the beams to the columns. The PT force closes the gaps that develop under earthquake loading, returning the frame to its initial pre-earthquake position (i.e. the frame is Ã¢Â€Âœself-centeringÃ¢Â€Â). Energy dissipation devices can be used to reduce the seismic response of an SC-MRF. PT fuse devices can be installed to enhance the collapse prevention performance of an SC-MRF.
The scope of this study includes validation of a performance-based design (PBD) procedure and a floor diaphragm concept, experimental and analytical studies of a large-scale SC-MRF test structure, and evaluation of the performance of the SC-MRF test structure.
A PBD procedure for SC-MRF systems from previous work was adopted and modified. A prototype 4-story 7×7-bay SC-MRF building was designed. A large-scale model of the prototype SC-MRF (denoted SC-MRF test structure) was developed. Static pushover experiments and earthquake hybrid simulations were conducted to study the connection behavior and system-level response of the SC-MRF test structure, as well as to validate the PBD procedure and associated design criteria.
Results from this study indicate the SC-MRF test structure performed well. Experimental results show the softening of the lateral force-lateral drift response of the SC-MRF test structure was due to gap opening at beam-to-column interfaces; the beams and columns of the SC-MRF sustained modest yielding; the SC-MRF test structure maintained self-centering behavior; the energy dissipation device used in the SC-MRF test structure dissipated an appropriate amount of seismic energy; the PT fuse device that was studied has the potential to reduce the probability of collapse under intense earthquake shak