Seismic Protection

• More connections equal better protection – The attachment of sheathing and finishes to the repetitive wood joists and studs in a typical wood-frame structure provides redundant load paths for an earthquake’s forces. If one connection becomes overloaded, its share can be assumed by those around it.
• Wood buildings are lighter – Wood has a high strength-to-weight ratio, which means that wood buildings tend to be lighter than other building types—a definite advantage in an earthquake.
• Wood buildings are flexible – The nailed wood connections in wood-frame systems allow the building to flex, thereby absorbing and dissipating energy during an earthquake.
• Wood buildings resist lateral forces – In engineered wood-frame buildings, structural panels (plywood or OSB), acting in combination with studs and joists, create shearwalls and diaphragms, which are very effective at resisting lateral forces.

Wood-frame construction makes it easy for building professionals to construct strong, durable buildings that meet code requirements and assure good performance in earthquakes and severe weather. It is essential, however, that the structure be properly detailed.

When building for seismic and high wind areas, a basic understanding of how lateral loads act on wood framing systems, and how construction detailing and fasteners affect the ultimate performance of a structure, is invaluable. Builders and designers can use these principles to ensure strength, quality and safety in many types of non-residential construction.

Sources

Design Concepts: Building in High Wind and Seismic Zones – APA – The Engineered Wood Association, 8 pages
Wood-Frame Construction: Meeting the Challenges of Earthquakes, Canadian Wood Council, 20 pages (1.7MB PDF)

More information

• Designing for Earthquakes - WoodWorks
• ANSI/AF&PA NDS-2005 – National Design Specification® (NDS®) for Wood Construction – American Wood Council/AF&PA standard, 268 pages
• ANSI/AF&PA SDPWS-2005 – Special Design Provisions for Wind and Seismic standard with Commentary – American Wood Council/AF&PA standard, 44 pages
• ANSI/AF&PA WFCM-2001 Wood Frame Construction Manual for One and Two-Family Dwellings with Commentary – American Wood Council/AF&PA standard, 320 pages
• Benchmarking Seismic Base Shear to Historical Practice, American Wood Council, 5 pages ( 94KB PDF)
• Design and Shear Walls – APA – The Engineered Wood Association, 32 pages
• EWS Data File: Lateral Load Connections for Low-Slow Roof Diaphragms – APA – The Engineered Wood Association, 24 pages
• Introduction to Lateral Design –APA – The Engineered Wood Association, 20 pages
• Seismic Requirements for Wood Building Design – Recent Changes to ASCE 7 and IBC, American Wood Council, 3 pages ( 66KB PDF)
• Technical Topics: IRC Exemption from Wall Bracing Requirements in Seismic Design Category C – APA – The Engineered Wood Association, 1 page