Dowden and Bruneau 2011
This paper mentioned about the details of a PT-RMC concept that could be implemented in steel plate shear wall and moment resisting frame systems. PT-RMC is an alternative MRF connection that provides frame self-centering and limits hysteretic damage to designated energy dissipation elements during earthquakes. The proposed connection was inspired by a moment resisting connection and named as “New Zealand-inspired-Buffalo Resilient Earthquake resistant Auto-centering while Keeping Slab Sound” (NewZ-BREAKSS).
System Concept
The connection is composed of light gage web plate, continues steel fish plate, shear plate, stiffener plate, post tensioned and continuity plate. NewZ-BREAKSS eliminates the beam growth by maintaining constant contact of the beam top flange with the column during lateral drift. Moreover, this connection provides a large moment arm from the rocking point to the centroid of the post-tension for maximizing the PT elongation desired for self-centering connections.
The two PT elements need to be anchored independently along the length of the beam, because during frame drift the top flange of the beam is in constant contact with the columns at both ends of the beam. When one of the rocking joint opens and induces PT elongation, the rocking joint at the opposite end of the beam closes and induces PT decompression.
Analytical Study, Results and Discussion
In order to verify the behavior of the proposed rocking connection and the hysteretic response of SPSWs having NewZ-BREAKSS connections, cyclic nonlinear static pushover analysis was first conducted using the computer program SAP2000.
By means of analytical study, the comparison of formulations developed describing the moment distribution along the HBE and also the system hysteretic response with the NewZ-BREAKSS connection, were done. It was observed that the proposed rocking connection provides re-centering capability as observed by the hysteretic plots.
Moreover, nonlinear time-history analysis was performed in SAP2000 in order to verify the performance of the self-centering SPSW system with the NewZ-BREAKSS rocking connection under a more realistic loading environment due to a ground motion excitation.
As a result, the NewZ-BREAKSS rocking connection provided the advantage of essentially no beam growth, thus mitigating damage to the floor diaphragm and beams while keeping the benefits of P
Reference
Dowden, D. M., Bruneau, M. (2011). “NewZ-BREAKSS: Post-Tensioned Rocking Connection Detail Free of Beam Growth,” Engineering Journal. Second Quarter. 2011.