Spring 2021
Highlights from this Month's e-Newsletter
Feature
Updated FTAO Shear Wall Design Tools
Pictured below, the Las Ventanas multifamily/mixed-used project was built with FTAO shear walls.
Designing force transfer around openings (FTAO) shear walls offers significant benefits. FTAO can be used for multiple openings and a wider range of wall sizes than possible with the segmented or perforated shear wall analysis methods. FTAO allows for the use of narrower wall segments while still meeting required height-to-width ratios, and there is a high likelihood that fewer hold-downs will be required, reducing costs.
FTAO shear walls use wood frames sheathed with wood structural panels (plywood or OSB) with wall penetrations, such as windows or electrical panels. Generally, flat steel straps are used at the corners of openings, above and below, to transfer tension forces, with flat blocking on the inside of the wall to transfer compression forces. The wood structural panels transfer shear forces, anchor bolts resist sliding and hold-downs resist overturning.
While the FTAO method requires comprehensive analysis, our recently updated tools support the design process, offering guidance and assistance with determining the required calculations.
Technical Note: Design for Force Transfer Around Openings
This technical note presents a rational analysis for applying FTAO to walls with asymmetric piers and multiple openings. It is based upon APA modeling and testing and uses methodology that assists the design professional in solving for the required sheathing, nailing, hold-downs, straps and maximum deflection. Updates include clarifying which shear capacity adjustments may be used in accordance with the 2018 IBC/SPDWS-15 versus the 2012 IBC/SPDWS-08, as well as clarifying that the length of corner straps need not run continuous across the full width of openings, only long enough to address corner forces. GET >
APA Force Transfer Around Openings Calculator
This calculator is an Excel-based tool for professional designers that uses FTAO methodology to calculate the maximum hold-down force for uplift resistance, the required horizontal strap force for the tension straps at each corner of the opening(s), the maximum shear force to determine sheathing type, attachment and the maximum deflection of the wall system. The calculator includes worksheets for shear walls with one, two and three openings and a design example. Updates to the calculator include improved error messaging based on inputs to pier length and Gt and Ga values; the addition of variable Vinduced, so the designer may use ASD or LRFD design methods to design for wind or seismic loads; and the option of selecting no aspect ratio factor. GET >
Multifamily Case Studies Using FTAO Shear Walls
Santa Barbara Apartments: Value engineering and a switch to glulam and wood-frame shear walls put this stalled Rialto, California, apartment project back on track. GET >
Las Ventanas: This modern, affordable housing complex in Long Beach, California, was developed in answer to the "Everyone Home Long Beach" initiative encouraging innovative, low-income community housing solutions. GET >
Getting Technical
Timber-Strong Design BuildSM Competition, 2021 Pacific Southwest Conference
UCLA's winning entry is reproduced at right.
APA, along with the American Wood Council and Simpson Strong-Tie, sponsored the American Society of Civil Engineers’ Pacific Southwest Conference Timber-Strong Design Build competition in March 2021. The competition’s goal is to provide unique insights and hands-on experience to the next generation of structural engineers involved in sustainable design and construction. To compete, student teams were tasked with designing and building a sustainable, aesthetically pleasing and structurally durable two-story wood building. By preparing a project bid, performing analysis and managing the construction process, each team acted as a design build construction firm while competing in a friendly environment.
In light of the COVID-19 pandemic, the in-person build was replaced with a virtual build, the creation of a building information model (BIM). Twelve universities competed in the virtual competition. Top honors went to:
1st place: University of California, Los Angeles
2nd place: California State University, Fullerton
3rd place: University of Hawaii at Manoa
APA, AWC and Simpson Strong-Tie also awarded two scholarships to students who participated in the competition.
Inside the Circle
Nonresidential and Multifamily Framer Training
Photo courtesy Structurlam Products Ltd.
Need assistance with training new talent? APA and WoodWorks are partnering to offer a two-part framing training to commercial construction professionals.
Frame it Right! Back to Basics for Big Buildings
The demand for commercial and multifamily construction is soaring, and the framing industry is expanding to meet this demand. APA – The Engineered Wood Association has walked hundreds of job sites and identified the most common wood construction framing errors found in today’s nonresidential buildings. This session examines the consequences of these framing mistakes from the ground up, providing practical solutions for avoiding typical issues using APA’s resources as a guide.
Learning Objectives
Be able to identify common pitfalls in the construction of low-rise wood buildings for floor, wall and roof systems in order to reduce liability and ensure greater client satisfaction.
Understand how the loads on a nonresidential wood building (gravity, lateral and moisture) influence framing and use this knowledge to effectively frame a building that mitigates negative effects of loading.
Understand how engineered wood products (EWP) may be used in a wide spectrum of applications and how to choose the EWP that most efficiently meets these needs.
Learn how to navigate technical resources (APA literature, including website content and publications) to address the challenges facing today’s nonresidential wood building framers.
Mass Timber Construction Management: Economics, Logistics & Risk Analysis
How do contractors answer the increasing demand for mass timber buildings from architects and ownership groups? Growing this budding industry requires an understanding from both designers and seasoned construction professionals of how to construct efficiently, navigate jurisdictions new to mass timber and manage the procurement risks to deliver the dream of a new and optimized building system. This session will introduce mass timber products and building systems, then consider why some mass timber projects never pass the concept stage, what can mitigate risk and improve financial feasibility and how the development, architectural, engineering and construction community can achieve success with mass timber projects of various scales and typologies. Particular emphasis will be given to preconstruction coordination, holistic approaches to costing and scheduling studies, project delivery methods and how to achieve the highest level of cost efficiency.
Learning Objectives
Understand the preconstruction manager’s role in material procurement and MEP coordination of code-compliant mass timber projects.
Highlight effective methods of early design-phase cost estimation and building official interaction on code compliance topics that keep mass timber options on the table.
Discuss potential construction schedule savings and construction fire safety practices realized through the use of prefabricated mass timber elements.
Explore best practices for interaction between manufacturer, design team and preconstruction manager that can lead to cost efficiency and safety on site.
To learn more about this training opportunity, contact Karyn Beebe, P.E., LEED AP. EMAIL >
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