Capacity Design Approach for Multi-Storey Timberframe Buildings

In this paper two analytical approaches for theapplication of the capacity design to timber framebuildings are presented. The first one (methodHDC) assumes that only the sheathing-to-framingconnection components can dissipate energysince, if well-designed, may be characterizedby a high ductility. Assuming a timber framewall as a statically determinate system, otherconnection devices (angle brackets and hold-downs) should be designed in relation to thestrength of the weakest component accordingto the design capacity approach. The provisionsregarding the local ductility should be satisfiedonly to the sheathing-to-framing connectionsand it seems correct to adopt a q factor relatedto a high ductility class of the structures. Thesecond method (approach MDC) is simplified andconsiders both fasteners and connection devicesable to dissipate energy. All of them are designedin relation to the analysis loads and the capacitydesign approach is applied only to timberelements. There is not a global control on themechanism failure (the weakest component maybe a fastener, an angle bracket or a hold-down)and the provisions about the local ductility areto be applied to all components (SH, A and H).In this case, since the ductility of connectiondevices is usually lower the fastener one, areduced value of the behaviour factor q shouldbe adopted.Some practical rules and expressions areproposed to apply the capacity design approachas requested by Standards. However, furtherstudies should be carried on, in order to selectthe value of the behaviour factor q for the twoapproaches (with particular regard to the secondone for medium ductility class), and to calibratethe value of the parameter φ, so to have asufficient distributed energy dissipation