Non-Linear Numerical Modelling of a Post-Tensioned Timber Frame Building with Dissipative Steel Angle Devices.

This paper describes the numerical modelling of post-tensioned timber (Pres-Lam) frame systems under non-linear dynamic and static loading. From the conception of the post-tensioned jointed ductile concept it has been clear that the nature of its controlled rocking mechanism leant itself well to the use of a lumped plasticity approach. This approach combines the use of elastic elements with springs representing plastic rotations in the system. Two experimental testing campaigns have been used in order to confirm the effectiveness of this modelling technique in predicting both the global (frame) and local (beam-column) response of these systems. The first of these tests was a full scale beam-column joint tested quasi-statically and the second was a 3-dimensional, 3-storey, 2/3rd scale multi-storey post-tensioned timber frame building tested dynamically. During the testing programmes the specimens were tested both with and without the addition of dissipative steel angles which were designed to yield at a certain level of drift. These steel angles release energy through hysteresis during lateral frame movement thus increasing damping. Both structures were modelled using a lumped plasticity approach with springs that were calibrated against the moment rotation design procedure used for post-tensioned timber connections. This work has proved the adequacy of the use of two numerical modelling programs, RUAUMOKO and SAP2000, in providing accurate representation of structural response when calibrated against current design procedures. All testing was performed in the structural laboratory of the University of Basilicata in Potenza, Italy. This experimental campaign is part of a series of experimental tests in collaboration with the University of Canterbury, Christchurch, New Zealand.