Seismic design of timber structures study group review, March 1986
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.
Dowrick, D J, "Hysteresis loops for timber structures".
Dowrick, D J and Smith, P C, "Timber shear walls for wind and earthquake resistance".
Smith, P C and Dowrick, D J, "Horizontal timber diaphragms for wind and earthquake resistance".
Dean, J A, Stewart, W G and Carr, A J, "Seismic behaviour of plywood sheathed shearwalls".
Moss, P J, Carr, A J and Buchanan, A H, "Seismic design loads for low rise buildings”.
Collins, M J, "Design data for nailed joints in shear".
Williams, R L (1983) "Timber and earthquake engineering", New Zealand Timber Design Society Newsletter No 12, October 1983.
Tyler, R G (1985) "Further notes on a steel energy absorbing element for braced frameworks", NZNSEE Bulletin, Vol 13, No 3, September 1985, pp 270-279.
Lowe, P G and Edwards, M R (1984) "Aspects of ductility in nailed timber connections", Proceedings or Pacific Timber Engineering Conference, Auckland, May 1984.
Thurston, S J and Flack, P F (1979) "Cyclic loading of large timber T joints incorporating steel side plates", MWD Central Laboratory Report No 5-79/6, Wellington, 1979,
Thurston, S J (1984) "In-plane cyclic shear tests on ply-sheathed bracing walls, MWD Central Laboratories Report No 5-84/2, Wellington, 1984.
Yap, K K (1984) "An investigation of damping characteristics and seismic response of ply box and nail plate portal frames", MWD Central Laboratories Report No 5-84/12, Wellington, 1984.
Phillips, M H, Wood, J H and Docherty, K (1984) "Horizontal vibration of houses", MWD Central Laboratories Report No 5-84/3, Wellington, 1983.
NZS 4203:1984 'Code of Practice for General Structural Design and Design Loading for Buildings1 , SANZ, Wellington, 1984, 100 pp.
NZS 3603:1981 'Code of Practice for Timber Design', SANZ, Wellington, 1981, 75 pp.
NZS 3615:1981 'Specification for Strength Properties and Design Methods for Construction Plywoods", SANZ, Wellington, 1981.
This work is licensed under a Creative Commons Attribution 4.0 International License.