Design of Mass Timber Diaphragms

Attendees can Earn 1.5 AIA/CES HSW LUs, 1.5 PDH credits or 0.15 ICC credits

When striving for material efficiency, the design of mass timber floor and roof systems to resist horizontal wind and seismic loading through diaphragm action is an important consideration. The design of diaphragms with mass timber panels typically follows one of two load path strategies. For diaphragms in nail-laminated timber (NLT), dowel-laminated timber (DLT), and glue-laminated timber (GLT) decking, a structural topping layer of wood structural panels is commonly used. For cross-laminated timber (CLT) diaphragms using CLT made from either solid sawn lumber or veneer-based structural composite lumber, the panels can be the primary diaphragm structural element. This presentation will provide detailed structural design and detailing recommendations for wind and seismic load-resisting diaphragms made from all of these products. It will also feature an in-depth review of the provisions for CLT diaphragm design in the American Wood Council’s code-referenced standard, 2021 Special Design Provisions for Wind and Seismic (SDPWS). To demonstrate practical design techniques, CLT diaphragm detailing options and examples will be presented based on WoodWorks’ new CLT Diaphragm Design Guide.