F. Sarti, T. Smith, A. Palermo, S. Pampanin, D. Bonardi & D.M. Carradine
High-performance post-tensioned technologies for seismic resistance were first developed in the late 1990s as the main outcome of the PREcast Seismic Structural Systems programme (PRESSS). Of these technologies the hybrid connection, composed of the combination post-tensioning strands/bars (re-centring) and some form of mild steel element (hysteretic dissipation), was the most promising. These systems are now also being applied to timber buildings. This paper focuses on the experimental study of a particular type of mild steel dissipation device: the fuse-type mild steel replaceable dissipater. This device is made up of a milled down plain mild steel bar and a confining tube filled with either epoxy or grout. The use of a milled area concentrates yielding over a defined length while the tube prevents buckling, similar to the Buckling Restrained Braces (BRB) used in steel frame buildings. The main purpose of the experimental campaign was to provide a comprehensive parametric study and preliminary guidelines for the design of the replaceable device. Several quasi-static push-pull tests were performed with varying geometric parameters such as the fuse diameter and length; two different filler materials were also used. Based on the experimental data collected, a simple analytical model was developed which is able to predict the force-displacement behaviour of the dissipater.
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