Tobias Smith

Post-Tensioned Glulam Beam-Column Joints with Advanced Damping Systems: Testing and Numerical Analysis

This article describes tests investigating a feasible source of passive damping for post-tensioned glue-laminated (glulam) timber structures. This innovative structural system adapts precast concrete PRESSS technology [Priestley et al., 1999] to engineered wood products combining the use of post-tensioned tendons with large timber members. Current testing is aimed at further improvement of the system through additional energy dissipation. Testing has favorably compared glue-laminated timber (not previously implemented in this way) with laminated veneer lumber (LVL) used in New Zealand. After initial benchmark testing with post-tensioning only, a simple, minimally invasive and replaceable type of hysteretic damper was added.

Experimental Performance and Structural Analysis of Plywood-Coupled LVL Walls

AbstractPrestressed-laminated timber (Pres-Lam) design has recently been adopted for multistory timber buildings based on ongoing research at the University of Canterbury, New Zealand. This system combines large timber members with unbonded posttensioning for recentering and ductile connections for energy dissipation. This paper describes the experimental, analytical, and numerical investigation of posttensioned laminated veneer lumber (LVL) walls coupled with plywood sheets subjected to both quasi-static cyclic and pseudodynamic seismic testing protocols. Different arrangements of nails, used to connect the plywood coupling panels with the posttensioned timber walls, have been tested to compare their energy dissipation characteristics. Simplified numerical macromodels with rotational spring elements have been developed to accurately represent the recentering contribution from the posttensioning and the pinched hysteric contribution of the nailed connections. The testing results provided good seismic perf...

Overstrength of dowelled CLT connections under monotonic and cyclic loading

This paper presents an evaluation of overstrength based on an experimental study on dowelled connections in Cross Laminated Timber (CLT). Connection overstrength needs to be well understood in order to ensure that ductile system behaviour and energy dissipation can be achieved under seismic loading. Overstrength is defined as the difference between the code-based strength, using characteristic material strengths, and the 95th percentile of the true strength distribution. Many aspects contribute to total connection overstrength, which makes its definition challenging. In this study, half-hole embedment tests were performed on CLT to establish embedment strength properties and three point bending tests were performed to determine the fastener yield moment. Different connection layouts, making use of mild steel dowels and an internal steel plate, were tested under monotonic and cyclic loading to evaluate theoretically determined overstrength values and study the influence of cyclic loading on overstrength. Experimental results were compared with strength predictions from code provisions and analytical models for ductile response under monotonic loading. It was found that cyclic loading does not significantly influence overstrength for connections that respond in a mixed-mode ductile way indicating that in future more expedient monotonic test campaigns could be used. This work also provides further experimental data and theoretical considerations necessary for the estimation of a generally applicable overstrength factor for dowelled CLT connections.