A New Hybrid Friction Damper (HFD) for Dual-Level Performance of Steel Structures

In this study, a new hybrid energy dissipation device is developed by combining two friction dampers (auxiliary and main fuse) in series to be used for the seismic control of two different earthquake intensities. Compared with the conventional friction dampers, the new hybrid damper has an advantage in that only the auxiliary fuse (with low sliding force) is activated for moderate earthquakes and both fuses work simultaneously for strong earthquakes. Cyclic loading tests of the combined hybrid dampers are carried out to evaluate their seismic energy dissipation capability. The obtained experimental force displacement indicates proper details of the new damper to create two performance levels. Finite element analyses of the test specimens are also carried out for comparison and have good agreement with the test results. Force–displacement characteristics, energy dissipation, and equivalent viscous damping are also derived and good agreement has been found. Moreover, it is demonstrated that by engaging the main fuse with non-loaded pretension bolts, the strength losses of the hybrid damper in the subsequent cycles are limited compared with the common friction dampers, which can be called the “resurrection-type” behavior of the main fuse in the main shocks. To evaluate the effects of the proposed damper, typical 3- and 9-story steel buildings are modeled and their seismic responses under 22 earthquake excitations are investigated using incremental dynamic nonlinear time-history. Comparison of incremental dynamic analysis (IDA) curves and their medians revealed that using a hybrid friction damper (HFD) reduces the probability of reaching all the defined damage states. Moreover, the reduction effect of HFD was recognizable in 9-story frames.