Seismic response of two-storey steel frame equipped with metallic yielding and viscous dampers under far- and near-field earthquakes: Shaking table tests and numerical investigations

Seismic energy dissipation technology is widely used in building structures to mitigate earthquake damage; two typical energy dissipation devices (EDDs), viscous fluid dampers (VFDs) and metallic yield dampers (MYDs), are often used. To investigate the effects of different types of EDDs on seismic performance, shaking table tests were conducted on a two-storey moment-resistance steel frame (MRSF). This study examined three types of damping schemes: VFDs only, MYDs only, and a combination of both. The test results showed that different damping schemes had different effective stiffnesses and damping ratios. The basic frequency and damping ratio of the MRSF with hybrid dampers increased by 36.18% and 38.41%, respectively, compared with those with VFDs only. Compared with the other two controlled MRSFs using a single type of EDDs, the MRSF equipped with hybrid dampers can effectively coordinate the control of interstorey drifts. To further analyse the impact of pulse-type ground motions (GMs) on the dynamic responses of the controlled MRSFs, numerical models were established for all test models, and the nonlinear time-history analysis (NTHA) was performed. The numerical results fitted well with the test results and showed that the hybrid damping scheme can take full advantage of the two types of EDDs. The mean dissipation energy ratio of the dampers was 86% with GMs with an intensity of 0.80 g. There was a significant difference in the seismic damping effect of the controlled MRSFs with different types of seismic excitations. The acceleration control effect of the MRSF with only MYDs was best with near-field pulse-type GMs, with up to a 30% reduction over the MRSF with only VFDs. The acceleration control effect of the hybridcontrolled MRSF was best with near-field non-pulse GMs; the 1st-storey acceleration control of the hybrid damping MRSF was reduced by up to 42.4% compared to the VFD. The displacement reduction rates of the three controlled MRSFs subjected to pulse-type seismic excitation were lower than those of the three MRSFs subjected to non-pulse-type seismic excitations.