Seismic safety

Seismic safety

Wood frame construction has superior seismic performance

Wood frame buildings are safer than concrete and masonry buildings in areas with a high risk of earthquakes. They save lives and reduce the cost of reconstruction.

Wood is strong, light and flexible. Wood buildings weigh significantly less than concrete buildings. This reduces loads on the structure, as well as the danger of heavy weights falling from above. The flexibility of the wood components allows the structure to deform and deflect momentarily in response to seismic forces without breakage, collapse or disconnection. Uplift and lateral loads are shared by the many wood members that make up the framework, the wood structural panels fastened to them, and the thousands of fasteners and connectors which tie the components together. This structural redundancy is stronger than predicted by conventional engineering analysis.

Additional measures can be taken in areas of greatest risk

In areas, where severe earthquakes are likely, the structural design of a standard wood frame can be enhanced simply and inexpensively. Additional measures include braced walls, reinforced connections between foundation and floor, and walls to roof, as well as steel rod tie-downs that clamp the top wall to the foundation.

Tests show multi-storey hybrid structures can survive the most severe earthquakes

A full-scale, seven-storey mixed use condominium tower (six wood frame storeys above a one-storey steel structure) was tested. Conducted in Kobe, Japan, this was the largest full-scale earthquake test in the world. The building was subjected to a simulated quake that was 180 per cent of the Northridge earthquake in California, and suffered no significant damage. This demonstrates that even mid-rise wood buildings can survive the most severe earthquakes. The test used Japan’s massive E-Defense Shake table, the largest shake table in the world.

Shake table test, Kobe, Japan
Shake table test, Tongji University, Shanghai