Design with Wood

Structural Design

Wood can be used in many types of non-residential and multi-family buildings, from repetitive single-story structures to multi-story offices and schools, industrial facilities, large arenas and more.

Because of its high strength-to-weight ratio, dead load is a smaller component of the total load factor than for heavier materials. Usually the lightest or least involved construction type appropriate for a given span that is capable of carrying the design load is the most preferable.

Like all building materials, wood has unique design properties. By understanding the nature of these properties, designers are able to maximize the positive attributes of materials and account for other effects. Unique properties that affect wood design include:

  • Duration of load effects – Wood has a greater capacity to carry short-term loads than sustained loads, which enhances its performance during seismic and high wind events.
  • System effects – Wood systems have the ability to distribute and mutually support loads, increasing their efficiency.
  • Size effects – Research has shown that smaller wood members are stronger per unit area than larger members.
  • Hygroscopicity – Wood’s ability to absorb moisture can affect both dimensional stability and strength.

Wood designers in the US can use either an Allowable Stress Design (ASD) format or a Load and Resistance Factor Design (LRFD) approach. The referenced ASD/LRFD design standard is the ANSI/AF&PA NDS-2005 National Design Specification® (NDS®) for Wood Construction. Published by the American Wood Council, this manual brings together all the required elements for the design of wood structures.

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