Three innovative massive wooden shear-wall systems (Cross-Laminated-Glued Wall, Cross-Laminated-Stapled Wall, Layered Wall with dovetail inserts) were tested and their structural behaviour under seismic action was assessed with numerical simulations. The wall specimens differ mainly in the method used to assemble the layers of timber boards composing them. Quasi-static cyclic loading tests were carried out and then reproduced with a non-linear numerical model calibrated on the test results to estimate the most appropriate behaviour factor for each system. Non-linear dynamic simulations of 15 artificially generated seismic shocks showed that these systems have good dissipative capacity when correctly designed and that they can be assigned to the medium ductility class of Eurocode 8. This work also shows the influence of deformations in wooden panels and base connectors on the behaviour factor and dissipative capacity of the system.
The seismic performance of a post-tensioned (PT) energy dissipating beam-to-column joint for glulam heavy timber structure is investigated in this paper. Such connection incorporates post-tensioned high-strength strand to provide self-centering capacity along with energy dissipating produced by a special steel cap, which is attached with the timber beam and also to prevent the end bearing failure of wood. The moment-rotation behaviour of the proposed posttensioned timber joint was investigated through a series of cyclic loading tests. The timber joint was loaded at the end of the beams to produce a moment at the joint, and the tests were conducted with three different post-tension forces in the steel strand. The hysteretic behaviour and self-centering capacity of the joint are evaluated based on the results from cyclic loading tests. The failure mechanism of the joint was illustrated through test observations, and the momentresisting capacity and energy dissipation of the joint were analysed with regard to various drift level. This research aims to provide possible solutions to minimize the residual deformation of heavy timber structure made of glulam in China.
Self-centring Cross-Laminated Timber (CLT) walls are a low damage seismic force resisting
system, which can be used to construct tall wood buildings. This study examines two
approaches to model self-centring CLT walls, one that uses lumped plasticity elements, and
another that uses fibre-based elements. Finite element models of self-centring CLT walls are
developed using the Python interpreter of Opensees, OpenSeesPy, and tested under monotonic
and reverse cyclic loading conditions. Outputs from the analysis are compared with data from
two existing experimental programs. Both models accurately predict the force displacement
relationship of the wall in monotonic loading. For reverse cyclic loading, the lumped plasticity
model could not capture cyclic deterioration due to crushing of CLT. Both models slightly
overpredict the post-tension force. Sensitivity analyses were run on the fibre model, which
show the wall studied is not sensitive to the shear stiffness of CLT.
OpenSeesPy models are also created of a two-story structure, which is tested dynamically
under a suite of ground motions. The structure is based on a building tested as part of the
NHERI TallWood initiative. During testing the foundation of the building was found to be
inadvertently flexible. To determine the appropriate model parameters for this foundation,
calibrations were performed by running a sequence of OpenSeesPy analyses with an
optimization algorithm. Outputs from the lumped plasticity and fibre models were compared
to experimental results, which showed that both could capture the global behaviour of the
system with reasonable accuracy. Both models overpredict peak post-tension forces. The suite
of analyses is then run again on the building to predict the performance with a rigid foundation.
Cyclic deterioration is more significant for the building with a rigid foundation, and as a result
the fibre mode is more accurate.
The objective of this research is to characterize of load-deformation responses of tested connections(stiffness, strength, ductility, energy dissipation, failure modes) by testing large STS connections with steel side plates under monotonic and cyclic loads.
Cross Laminated Timber (CLT) is gaining acceptance in tall building applications in the US. However, there are knowledge gaps concerning long-term performance, particularly effects due to moisture intrusion and biological decay in relation to connection systems. In a risk-averse industry, this knowledge gap impedes acceptance of CLT. The overall goal of the project is to characterize the effects of moisture accumulation in mass timber buildings on properties of building components and connections. The project will assess CLT connectors using small-scale assemblies, then use these data to develop predictive models that will be compared with full-scale tests. Connection assemblies will be constructed with two wood species and exposed to five moisture/biological regimes. Moisture behavior in the assemblies will be characterized using a combination of non-destructive tools, such as ultrasonic, wave propagation, CAT-Scan, and infrared imaging. The data generated from cyclic loading tests will be used to calibrate the SAWS connection model. This will provide a novel way to estimate the effects of moisture and biological degradation on connections. A deliverable for this project is a design guideline for engineers to account for the effects of moisture intrusion and subsequent fungal decay on panel and connection properties.
