Experimental Investigations of Post-Tensioned Timber Frames with Advanced Seismic Damping Systems

This paper describes initial experimental testing to investigate feasible sources of passive damping for the seismic design of post-tensioned glue laminated timber structures. These innovative high performance structural systems extend precast concrete PRESSS technology to engineered wood structures, combining the use of post-tensioning bars or cables with large post-tensioned timber members. The combination of these two elements provides elastic recentering to the structure while the addition of damping using a specialised energy dissipation system gives the desirable `flag shaped' hysteretic response under lateral loading. Testing has been performed on a full scale beam-column joint at the University of Basilicata in Italy in a collaborative project with the University of Canterbury, New Zealand. The experimental testing uses engineered wood products, extending the use of laminated veneer lumber (LVL) structures tested in New Zealand to testing of glue laminated timber (glulam) structures in Italy. Current testing is aimed at further improvement of the system through additional energy dissipation systems. After initial benchmark post-tensioned only testing an innovative source of hysteretic damping was added and tested. These tests show that the system is directly applicable to glulam considering testing both with and without additional damping devices exhibited excellent results. The addition of damping devices increased values of equivalent viscous damping from 2% for the post-tensioned only system to a maximum of 16%.