Experimental response of a large-scale two-storey steel building equipped with low-yielding friction joints

The recent earthquakes have underlined the need for more advanced design philosophies able to avoid or reduce direct and indirect costs related to the occurrence of destructive seismic events. According to the traditional seismic design approach, under rare and very rare seismic events, the onset of damage to structural components is usually accepted. However, to address social expectations and the need for resilient buildings, recently, novel low-damage design philosophies have been proposed. These are based on the introduction of friction devices able to dissipate large amounts of energy with negligible damage. The cost of repair of these devices is typically only related to the re-tightening of bolts and, eventually, the substitution of friction shims. Noteworthy examples of this technology are the Sliding Hinge Joints (SHJs), developed at the University of Auckland, and the FREEDAM joints, developed at the University of Salerno within the framework of a homonym research project. In the last two decades, significant efforts have been devoted to understanding the seismic behaviour of such connections. The novelty of this work consists in investigating, for the first time, the seismic response of a large-scale building mock-up equipped with FREEDAM joints. The mock-up has been tested with a sequence of five accelerograms using the pseudo-dynamic testing method. The results have confirmed that FREEDAM connections provide large energy dissipation and rotation supply with almost no damage. The experimental results have been used to verify the accuracy of a numerical model developed with the software OpenSees, showing the capabilities of current simplified phenomenological modelling approaches in capturing the actual structural response