Part 3 of this series will take an in-depth look at cantilever diaphragm design processes. Using calculation steps per ASCE 7 and the 2015 edition of the American Wood Council’s Special Design Provisions for Wind & Seismic (SDPWS), diaphragm force distribution will be used to illustrate diaphragm design procedures in an open front structure. Diaphragm chord forces, chord slip, and chord design and detailing will all be examined. Diaphragm flexibility will also be analyzed, reviewing options proposed for the 2021 SDPWS and other rational, engineering judgement-based approaches. Finally, diaphragm deflection and story drift calculations will be explained, emphasizing factors that contribute to story drift in a cantilever diaphragm, and measurement criteria.
By the end of the course, you will be able to do the following:
- Discuss evolutions in mid-rise building typology that have led to the need for open-front diaphragm analysis.
- Review diaphragm flexibility provisions in ASCE 7 and the 2015 Special Design Provisions for Wind & Seismic (SDPWS).
- Explore one option for open-front diaphragm analysis under seismic and wind loading in a wood-frame structure.
- Highlight how to calculate story drift, diaphragm deflection and torsional irregularities, and discover their effects on load distribution through a cantilever diaphragm structure.