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Summary

Cross-laminated timber (CLT) is an innovative wood product that was first developed some 20 years ago in Austria and Germany and ever since has been gaining popularity in residential and non-residential applicationsin Europe. European experience shows that this system can be competitive, particularly in mid-rise and high-risebuildings. In this chapter, a literature review on the research work conducted around the world related to the seismic performance of cross-laminated timber (CLT) wall panels and structures is included. This is followed by the results from a series of quasi-static tests on CLT wall panels that were conducted at FPInnovations’ Wood Products laboratory in Vancouver. CLT wall panels with various configurations and connection details were tested. These configurations included single panel walls with three different aspect ratios, multi-panel walls with step joints and different types of screws to connect them, as well as two-storey wall assemblies. Connections for securing the walls to the foundation included off-the-shelf steel brackets with annular ring nails, spiral nails, and screws; combination of steel brackets and hold-downs; diagonally placed long screws; and custom made brackets with timber rivets. Results showed that CLT walls can have adequate seismic performance when nails or screws are used with the steel brackets. Use of hold-downs with nails on each end of the wall improves their seismic performance. Use of diagonally placed long screws to connect the CLT walls to the floor below is not recommended in high seismic zones due to less ductile wall behaviour and to the sudden screw pull-out failure mechanism. Use of step joints in longer walls can be an effective solution not only to reduce the wall stiffness and thus reduce the seismic input load, but also to improve the wall deformation capabilities. Timber rivets in small groups with custom made brackets were found to be effective connectors for CLT wall panels. In addition, this chapter includes a survey of potentially available methods for development and assessment of R-factors for different structural systems. Studies conducted in Europe on the assessment of the behaviour q-factor (European R-factor equivalent) for CLT structures and their findings are also discussed. Finally, based on all available information, estimates were made on the values of R-factors for CLT structures according to the National Building Code of Canada, and capacity-based design procedures for CLT structures were drafted.

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