Seismic design of timber structures study group review, March 1986

  • R. Williams Ministry of Works and Development, Hamilton, New Zealand


Timber structures have had a reputation for performing comparatively well in earthquakes. However other structural materials now have design codes and recommendations that considerably improve their performance during earthquakes. In addition the form of timber structures has changed considerably in recent years, typically with less timber, bigger spans and less non-structural walls. Design recommendations and codes need to be reviewed and rewritten to ensure adequate performance is achieved.

In 1965 New Zealand Standards issued NZS 1900 Chapter 8, Design Loads. This code of practice set the basic levels of seismic loading to be designed for in New Zealand, and while they have been modified and refined, the principles established still exist in our present code (NZS 4203:1984) today. The 1965 code was the first code to make reference to the principle of ductility, the abi1ity of some materials and structures to be deformed briefly beyond their elastic limit without catastrophic failure. The ability to withstand large displacements temporarily permitted design loadings to be used which are considerably lower than would have been the case had the structure been assumed to be brittle and thus been required to remain elastic through any seismic disturbance. A corollary is that non-ductile failure of any member must be suppressed by consideration of the capacity loads on it that can be generated by the yielding mechanism.


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How to Cite
Williams, R. (1986). Seismic design of timber structures study group review, March 1986. Bulletin of the New Zealand Society for Earthquake Engineering, 19(1), 40-47.