Ruizhao Shu, Tong Guo, Solomon Tesfamariam, and Yanqing Xu 2022
A self-centering viscous-hysteric device (SC-VHD) is proposed to be equipped to moment resisting, steel frames and subjected to shake-table tests. A three-story steel frame equipped with the SC-VHD was tested in mainshock-aftershock (MSAS) loading sequences and its performances was analyzed in terms of peak and residual drifts. The experimental results from the performed tests are evaluated to determine the effectiveness of the SC-VHD in reducing damage and peak displacement. Numerical simulations are further used to validate experimental results to 6-, 9-, and 12-story steel buildings equipped with the SC-VHD. The ability for the SC-VHD to dissipate energy, along with the capacity to reduce the deformation and acceleration amplification during the MSAS loading sequences was assessed to improve the seismic performance of steel strcutures.
System Concept
The self-centering viscous-hysteric system (SC-VHD) is a self-centering system including both a velocity-related viscous energy dissipation and displacement-related hysteric energy dissipation. The SC-VHD comprises of a viscous damper and preloaded ring springs connected in parallel. The preloaded ring spring provides the recentering ability and displacement-proportional hysteric energy dissipation, while the viscous damper provides the velocity-proportional vicious energy dissipation.
Experimental Study, Results and Discussion
A shake table test was used to investigate the seismic performance of a prototype 3-story steel frame building equipped with the proposed SC-VHD. The steel frame equipped with the SC-VHD is tested under different seismic loading intensities: frequently occurring earthquakes (FOE), fortification earthquakes (FE), and rarely occurring earthquake (ROE). The SC-VHD is initially tested under cyclic loading tests to ensure that its mechanical and hysteric behaviors agreed with its design targets. The SC-VHD was thereafter tested on the steel MRF under varying magnitudes of mainshock-aftershock loading sequences. For each loading intensity, the peak acceleration and displacement was determined. The seismic response of each test was measured with accelerometers and displacement transducers attached to each SC-VCD. The experimental results demonstrated that the SC-VHD was extremely effective in significantly reducing peak drift and residual drift. Additionally, the maximum average acceleration amplification ratio of the steel frames equipped with the SC-VHD was significantly reduced as compared to the steel frame tested without the proposed device. The proposed SC-VHD was further evaluated in increasing numbers of stories as the device was equipped to 6-, 9-, and 12-story steel frames. Numerical simulations validated that peak and residual drift can be reduced for increasing number of stories. Overall, the peak drifts, residual drifts, acceleration amplification ratios, and the base shear of the 3-story frame with the SC-VHD can be reduced by 30%-50%, 50%-80%, 25%-35%, and 20%-35%, respectively. The proposed device has shown the capacity to dissipate up to approximately 70% of input energy.
Reference
Ruizhao Shu, Tong Guo, Solomon Tesfamariam, and Yanqing Xu; (2022). “Shake-Table Tests and Numerical Analysis of Steel Frames with Self-Centering Viscous-Hysteric Devices under the Mainshock-Aftershock Sequences.” Journal of Structural Engineering