March 29-31, 2012, Chicago, Illinois, United States
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.
Cross-Laminated-Timber (CLT) is increasingly gaining popularity in residential and non-residential applications in North America. To use CLT as lateral load resisting system, individual panels need to be connected. In order to provide in-plane shear connections, CLT panels may be joined with a variety of options including the use of self-tapping-screws (STS) in surface splines and half-lap joints. Alternatively, STS can be installed at an angle to the plane allowing for simple butt joints and avoiding any machining. This study investigated the performance of CLT panel assemblies connected with STS under vertical shear loading. The three aforementioned options were applied to join 3ply and 5-ply CLT panels. A total of 60 mid-scale quasi-static shear tests were performed to determine and compare the connection performance in terms of strength, stiffness, and ductility. It was shown that – depending on the screw layout – either very stiff or very ductile joint performance can be achieved.