Structural Glued Laminated Timber of Softwood Species

ANSI 117-2020: Standard Specification for Structural Glued Laminated Timber of Softwood Species

For structural engineers and designers specifying timber for demanding applications, understanding the foundational standards is paramount. ANSI 117-2020, the "Standard Specification for Structural Glued Laminated Timber of Softwood Species," provides an essential framework for the reliable use of this engineered wood product. This authoritative standard ensures that structural glued laminated timber (glulam) meets rigorous performance criteria, contributing to the safety and longevity of buildings and infrastructure.

What is ANSI 117-2020?

Published by APA – The Engineered Wood Association, ANSI 117-2020 is an American National Standard that establishes comprehensive requirements for the design and manufacture of structural glued laminated timber derived from softwood species. Its primary purpose is to provide engineers and manufacturers with the necessary reference design values and specifications to ensure the structural integrity and performance of glulam members.

Scope & Purpose

This standard governs the material properties, design values, and layup requirements for structural glued laminated timber. It covers the selection of lumber, adhesive bonding, and the determination of reference design stresses for various softwood species. While it provides the basis for design values, it explicitly states it is not a design manual or textbook; structural design itself must adhere to complementary codes like the National Design Specification (NDS) for Wood Construction. It does not cover utility structures or provide interpretations of the standard.

Who Must Comply?

• • Primary audience: Structural engineers, architects, timber fabricators, construction managers, and building inspectors.
• • Industries affected: Construction, timber manufacturing, wood product industry, building design and engineering.
• • Compliance nature: Voluntary, as per ANSI guidelines, but often mandated by building codes and project specifications.
• • Enforcement: Typically enforced through project specifications, third-party quality assurance programs, and building code compliance reviews.

Key Requirements Overview

The standard requires stringent adherence to material grading rules for laminating lumber, ensuring consistent quality. Professionals must ensure that glulam members are designed using reference design values provided within the standard, which are intended for adjustment per the NDS. Key provisions include detailed specifications for balanced and unbalanced layups, the use of specific softwood species, and the determination of adjusted design stresses for various load conditions. Furthermore, the standard outlines requirements for appearance grades and member shapes, ensuring both structural performance and aesthetic considerations are addressed.

Related Standards & References

ANSI 117-2020 works in conjunction with other critical standards. The National Design Specification (NDS) for Wood Construction is essential for the actual structural design of glulam members, leveraging the design values provided by ANSI 117-2020. ANSI A190.1 – American National Standard for Wood Products-Structural Glued Laminated Timber provides complementary manufacturing specifications. For utility structures, ANSI O5.2 provides conversion factors to adapt the reference design values.