Abstract
A hybrid recentering energy dissipative device that has both recentering and energy dissipation capabilities is proposed and studied in this paper. The proposed hybrid device, referred to as the hybrid shape memory alloy (SMA) recentering viscous fluid (RCVF) energy dissipation device, connects the apex of a chevron brace to an adjoining beam using two sets of SMA wires arranged in series on either side of the brace and a viscous fluid damper arranged in parallel with the SMA wires. The viscous damper is used because being a velocity-dependent device it does not exert any force that counteracts the recentering force from the SMA wires after the vibration of the frame ceases. In the numerical study, the Wilde’s SMA constitutive model is used to model the SMA wires, and the Maxwell model is used to simulate the viscous fluid damper. To demonstrate the viability and effectiveness of the proposed hybrid device, comparative studies are performed on several single-story shear frames and a series of four-story steel frames. The results show that the frames equipped with the hybrid device have noticeably smaller peak top story displacements and residual story drifts when subjected to ground motions at three different intensity levels.
Highlights
The concept of performance-based seismic design (PBSD) was developed as a result of a series of devastating earthquakes that occurred in the 1990s [1,2,3]
By comparing the residual story drift (RSD) values of the SF-RC and SF-recentering viscous fluid (RCVF) frames shown in Figures 13(d) to 13(f), one can see that the recentering effect of the shape memory alloy (SMA) wires is not fully realized without the viscous fluid damper
A hybrid device was proposed to enhance the recentering and energy dissipation capabilities of frames designed in the context of performance-based criteria
Summary
The concept of performance-based seismic design (PBSD) was developed as a result of a series of devastating earthquakes that occurred in the 1990s [1,2,3]. Under a certain temperature range, SMAs can exhibit superelasticity effect in which they can undergo relatively large strain (up to 8%) [6] without showing permanent deformation and with a stress-strain curve that exhibits a distinctive plateau and a hysteresis These features make SMAs ideal for use in recentering devices. The hybrid device is made from two sets of SMA wires and a viscous fluid damper, the former for recentering and the latter for energy dissipation purposes. To further demonstrate the effectiveness of the proposed hybrid device in mitigating earthquake damage to buildings, a series of six four-story steel frames are analyzed using nonlinear time history procedure, and their peak top story displacements and residual story drifts are compared. The numerical analysis results are summarized and conclusions are made
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