Seismic resilient bracing structure equipped with hybrid device at base

Abstract

Interest in the seismic resilience of structures has led to the development of smart buildings that not only meet life safety requirements like code-compliant conventional structures, but can also adapt to, as well as recover, in the event of an earthquake. A new Hybrid Smart Rocking braced frame (HSR) is proposed, which encompasses an elastic braced framed structure with a hybrid device at the column bases of the braced spans. The hybrid device includes a Viscous Damper (VD) and Shape Memory Alloy Yielding Device (SMAYD) that individually responds to nonlinear action demand of structures so that the rest of the structure remains elastic during a seismic event. The goal of this system is to retrofit the conventional structure to the seismic resilient structure by localizing nonlinear deformations in a limited number of hybrid devices beyond the structure as structural self-centering fuses with simple inexpensive recovery and removal of residual drifts. As opposed to conventional rocking structures, HSR systems do not require an adequate restoring force provided by the tributary vertical weight to the rocking columns or post-tensioning cables, because the self-centering performance of this system can be originally supplied solely by SMAYD. To configure the system, the mechanics of the HSR system is outlined, then various HSR structures are seismically evaluated subjected to 67 far-field ground motions through Incremental Dynamic Analysis (IDA). In the probabilistic seismic assessment framework fragility curves, seismic collapse metrics, and hazard curves are also derived from IDA results. The results indicate acceptable structural performance of the proposed HSR structure in comparison to conventional structures. The HSR system has no residual drifts and its collapse margin ratio is about 2.6–3.7, which is sufficiently greater than 1.0. The enhanced performance of the HSR system can eliminate the need for expensive repairs or demolition as the seismic resilient structure after an event in retrofitting programs that is otherwise to be expected for conventional ductile fixed base structures, which sustain severe damage.