Dynamic Tests on a Steel Frame Equipped with Hysteretic and Visco-Re-Centring Energy Dissipating Bracing Systems

Abstract

An extensive program of dynamic experimental tests, named JetPacs (Joint Experimental Testing on Passive and semiActive Control Systems), has been carried out at the Structural Laboratory of the University of Basilicata considering a 1:1.5 scaled three-dimensional steel frame, derived from a 2-storey, 1-bay prototype building. The JetPacs Project was developed within the RELUIS 2005-08 project, founded by Italian Dept. of Civil Protection. This work refers to the experimental tests on the model equipped with two different EDB systems based on Hysteretic Dampers (HD) and visco-re-centering devices (SMA+VD). The devices were designed with the purpose of limiting the inter-storey drifts so that the frame yielding is surely prevented. The visco-re-centering device was obtained by coupling Viscous Dampers (VD), with re-centering device based on shape memory alloy (SMA) wires, while the Hysteretic Damper was constituted by low-carbon U-shaped steel plates. The main objective of this paper is to compare the seismic response of the structure with SMA+VD and HD EDB's in order to calibrate a new performance based design procedure for the evaluation of the mechanical characteristics of SMA+VD devices. In this paper, the experimental results of the shaking table tests, in terms of comparison of both design solutions which lead to a comparable level of protection for the framed structure, are shown. The results obtained by numerical nonlinear time history analysis (NTHA) of both design solutions are also showed and compared with experimental ones.