Development of Ductility-related Modification Factor for CLT-Coupled Wall Buildings with Replaceable Shear Link Coupling Beams

The desire of using sustainable materials has reignited the interest in timber-based construction. Researchers and practitioners are developing novel timber-based structural solutions. Cross-laminated timber (CLT) coupled-wall is a recently proposed system for potential use in mid- and high-rise timber construction. The National Building Code of Canada, however, does not include this system and consequently, the seismic force modification factors are not available. This study evaluates the ductility-related force modification factor (Rd=4) using the FEMA P-695 procedure. Nine archetype buildings are designed considering different design parameters: building storey height, CLT wall configuration, and coupling ratios. Using 30 ground motion records (bi-directional), rigorously selected for seismicity of Vancouver - Canada, incremental dynamic analyses are performed. Collapse margin ratios are calculated to assess the adequacy of the trial Rd factors. Using an over-strength factor of 1.5, Rd=4 is found to be acceptable for this system.