Environmental Impacts of Multi-Storey Buildings Using Different ...

- 38 -residual/permanent deformations). These innovative solutions, typically referred to as jointedductile connections or PRESSS-technology, differ from monolithic solutions (i.e. cast-inplacereinforced or pre-cast concrete; welded or bolted connections in steel) in that:a) Prefabricated structural elements are connected using unbonded post-tensioning;b) The inelastic seismic demand is accommodated within the connection through theopening and closing of an existing gapc) The structural elements are kept in the elastic range with a very limited level of damage.A particularly efficient solution is provided by the hybrid system where an adequatecombination of self-centreing capacity (unbonded tendons plus axial load) and energydissipation (mild steel or other dissipation devices) leads to a controlled rocking motion underseismic action.This pre-cast concrete technology has been successfully adapted for timber frame and wallsystems. Due to its high homogeneity and good mechanical properties, laminated veneerlumber (LVL) has been selected as the preferred engineered wood material.Figure 4.12Figure 4.12Figure 4.12 shows the conceptual solution for a hybrid beam-columntimber connection, based on the combination of post-tensioning and internal dissipaters (e.g.epoxied mild steel bars).Internal or externaldissipation devicesRocking motionSelf-centering Energy dissipationMMHybrid systemMθθθUnbonded posttensionedtendonθ impUnbonded posttensionedMild steel ordissipative devicesFigure 4.12. Basic concept of hybrid jointed ductile connections for LVL timber frame systems and flagshapehysteresis behaviour [3].4.4.3 Experimental InvestigationThe University of Canterbury has carried out extensive experimental tests on timber exteriorbeam-column subassemblies, cantilever columns, single walls and coupled walls. Typicaltest-setups are shown in Figure 4.13.Figure 4.13. Test set-up of exterior beam-column joint, (single) cantilever wall, cantilever columnspecimens.