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.
Timber-Concrete Composite (TCC) systems have been employed as an efficient solution in medium span structural applications; their use remains largely confined to European countries. TCC systems are generally comprised of a timber and concrete element with a shear connection between. A large number of precedents for T-beam configurations exist; however, the growing availability of flat plate engineered wood products (EWPs) in North America has offered designers greater versatility in terms of floor plans and architectural expression in modern timber and hybrid structures. The opportunity exists to enhance the strength, stiffness, fire, and vibration performance of floors using these products by introducing a concrete topping, connected to the timber to form a composite. A research program at the University of British Columbia Vancouver investigates the performance of five different connector types (a post-installed screw system, cast-in screws, glued-in steel mesh, adhesive bonded, and mechanical interlocking) in three different EWPs (Cross-Laminated-Timber, Laminated-Veneer-Lumber, and Laminated-Strand-Lumber). Over 200 mid-scale push-out tests were performed in the first stage of experimental work to evaluate the connector performance and to optimize the design of subsequent vibration and bending testing of full-scale specimens, including specimens subjected to long-term loading.
April 14-16, 2011, Las Vegas, Nevada, United States
Wood-concrete composite systems are well established, structurally efficient building systems for both new construction and rehabilitation of old timber structures. Composite action is achieved through a mechanical device to integrally connect in shear the two material components, wood and concrete. Depending on the device, different levels of composite action and thus efficiency are achieved. The purpose of this study was to investigate the structural feasibility and effectiveness of using truss plates, typically used in the making of metal-plate-connected wood trusses, as shear connectors for laminated veneer lumber (LVL)-concrete composite systems. The experimental program consisted of two studies. The first study established slip-modulus and ultimate shear capacity of the truss plates when used in an LVL-concrete push out assembly. The second study evaluated overall composite bending stiffness and strength in two full size T-beams when subjected to four-point bending. One beam employed two continuous rows of truss plates and the other employed one row. It was found that the initial stiffness of both T-beams was similar for one and two rows of truss plates but that the ultimate capacity was approximately 20% less with the use of only one row.