Seismic analysis of multi-storey timber buildings braced with a CLT core and perimeter shear-walls

The seismic behaviour of multi-storey heavy-frame timber building superstructures braced by Cross-Laminated-Timber (CLT) shear-walls is investigated based on numerical linear dynamic simulations. All systems analysed have the same rectangular plan footprint dimensions, type of framework and shear-walls arrangement at each storey. For structural efficiency, the layout of lateral load-resisting systems combines a central building core with partial length perimeter shear-walls. What differs between cases is the number of storeys (3, 5, or 7), components specifications, and shear-walls anchoring methods. Special attention is paid to examining how the vertical joints between CLT shear-walls affect the seismic response. The properties of connections used in the analyses are obtained from testing of hold-down anchors and angle-bracket shear connectors. Results of the simulations demonstrate that mid-rise buildings are prone to effects of the lateral flexibility and transfer high uplift loads to the foundations during design level seismic events. By implication, special design measures may be necessary to limit the lateral drifts to the levels prescribed by the standards. Simplified representations of connection properties may yield to inappropriate predictions of lateral drifts of superstructures during seismic events, and to an improper design of connections. In future, the efficient realisation of multi-storey heavy-frame timber building superstructures braced by CLT shear-walls depends on the use of proper connection devices. Suitable devices may include metal tie-downs capable of reducing the inter-storey drift, while transferring forces to foundations in a manner that does not locally damage frameworks, shear-walls, or floor and roof diaphragms.