Hybrid simulation testing of a self-centering rocking steel braced frame system.

SUMMARY The self-centering rocking steel frame is a seismic force resisting system in which a gap is allowed to form between a concentrically braced steel frame and the foundation. Downward vertical force applied to the rocking frame by post-tensioning acts to close the uplifting gap and thus produces a restoring force. A key feature of the system is replaceable energy-dissipating devices that act as structural fuses by producing high initial system stiffness and then yielding to dissipate energy from the input loading and protect the remaining portions of the structure from damage. In this research, a series of large-scale hybrid simulation tests were performed to investigate the seismic performance of the self-centering rocking steel frame and in particular, the ability of the controlled rocking system to self-center the entire building. The hybrid simulation experiments were conducted in conjunction with computational modules, one that simulated the destabilizing P-Δ effect and another module that simulated the hysteretic behavior of the rest of the building including simple composite steel/concrete shear beam-to-column connections and partition walls. These tests complement a series of quasi-static cyclic and dynamic shake table tests that have been conducted on this system in prior work. The hybrid simulation tests validated the expected seismic performance as the system was subjected to ground motions in excess of the maximum considered earthquake, produced virtually no residual drift after every ground motion, did not produce inelasticity in the steel frame or post-tensioning, and concentrated the inelasticity in fuse elements that were easily replaced. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]