APA Force Transfer Around Openings (FTAO) Calculator
Why use the APA FTAO Calculator?
Wood structural panel sheathed shear walls and diaphragms are the primary lateral-load-resisting elements in most wood-frame construction. As wood-frame construction is continuously evolving, designers in many parts of the U.S. are optimizing design solutions that require the understanding of force transfer between elements in the lateral load-resisting system.
Shear walls designed with force transfer around openings (FTAO) offer some advantages compared to other types of shear wall design:
More versatility. Designing with FTAO allows for the use of narrower wall segments while meeting required height-to-width ratios.
A high likelihood that fewer hold-downs will be required.
How does the APA FTAO Calculator work?
APA’s Force Transfer Around Openings (FTAO) calculator is a free Excel-based tool for professional designers that uses FTAO methodology to calculate hold-down force for uplift resistance, the required horizontal strap force for the tension straps above and below openings, the shear force to determine sheathing attachment, and the deflection of the wall system. The calculator includes worksheets for shear walls with one, two and three openings and a design example.
The FTAO methodology used in this calculator was verified through APA testing of a wall with asymmetric piers and multiple openings, as discussed in APA’s Joint Research Report: Evaluation of Force Transfer Around Openings – Experimental and Analytical Studies, Form M410. This methodology is based on the Diekmann method.
Versatile Shear Wall Design Method Lends Greater Flexibility
Want to learn more about Force Transfer Around Opening (FTAO)? Explore related resources below, including a case study, videos and technical publications.
Published by APA — The Engineered Wood Association.
