Ductile or Non-ductile, that is the Question

There has been, over the years since the mid 80’s, an erosion of areas where in New Zealand timber buildings could traditionally compete with steel. Ongoing research by the steel industry (HERA and Steltech) has meant that purpose made steel members can be provided economically for commercial and especially industrial buildings. All connections have been clarified and ductility’s demonstrated. In competition with this the timber option nowadays is often not the most economic. Many NZ design engineers will wish to achieve ductility in any structure, no matter what the design approach and this attitude should be encouraged. Clarification of demands in the Loadings Code is needed and the material standard extended to clarify ‘capacity design’ factors and procedures for a wider range of structural elements. Growth in timber usage in the NZ building industry can only come from:* Architects ----creating a deliberate design in timber where other material alternatives are not an issue* Client /developers---considering alternative schemes using timber with proven well documented cost advantages. Currently this is only occurring in apartment buildings.* Possible new areas --- such as medium rise commercial, suburban or fringe CBD.This growth will not eventuate unless designers have a clear direction from Codes of Practice and are also confident that theoretical approaches match the practical realisation. There is a demonstrable need for ongoing timber industry research to clarify expected ductilities of various timber assemblages especially newer EWP forms (eg Triboard). Results from this research would clarify aspects of the NZ loadings and material code that currently cover timber usage.