A new automated tool developed by APA – The Engineered Wood Association assists structural engineers in the design of force transfer around openings (FTAO) shear walls. The APA FTAO Calculator and APA Technical Note: Design for Force Transfer Around Openings (FTAO) match up the popular method’s design challenges with straightforward solutions and accurate design calculations. Both items are available free of charge.
The FTAO method of shear wall design provides structures with a more comprehensive lateral resistance design which otherwise omitted the sheathing around windows or other large openings. Structural building system designs that incorporate lateral force resistance can be a challenge, especially as larger and more numerous windows in buildings increase in popularity. Such structural designs have resulted in substantially reduced lateral resistance, a high-risk trend considering the severe storms and earthquakes encountered across North America year after year.
“The FTAO method used to be considered cumbersome and somewhat undefinable due to the lack of specificity in the design code,” said Jared S. Hensley, P.E., APA Engineered Wood Specialist. “Now we have a new tool that simplifies the structural design process and makes the FTAO method more approachable and more precise.”
Many FTAO design techniques developed over time by several different organizations raised disputes among design professionals as to their accuracy and ease of use. The FTAO method is known to be critical to the safety and security of structures in high-wind and seismic zones, but if it was considered to be too time consuming or unclear, what structural engineers would use it? APA performed full-scale tests on FTAO design methodology with the hope of addressing design professionals’ issues. The results proved that application of the FTAO methodology is not only a practical approach, but also has the most design flexibility.
The APA FTAO Calculator provides the required hold-down forces, tension strap forces, and wall sheathing capacity and automatically completes the design check in the final step. It also provides shear wall deflection calculations for the 3- and 4-term deflection equation options. The free calculator can be downloaded from the APA website at https://www.apawood.org/ftao.
The APA Technical Note: Design for Force Transfer Around Openings (FTAO), Form T-555, defines the methodology and provides examples and step-by-step guidance on incorporating the methodology into structural designs with the use of the FTAO Calculator. The Technical Note can be downloaded from the APA website at https://www.apawood.org/ftao.