Engineered Aseismic Masonry Veneers (Aseismic-Resisting the Destructive Forces of Earthquakes)

With a total population less than that of Philadelphia and about that of San Francisco, New Zealand is a country of acknowledged seismicity, a reality well reflected in the building regulations. Unreinforced veneers are restricted in height and are domestic in scale. About a quarter of the existing housing stock displays brick, either in whole or in part. The provisions of NZS 3604:1984[1] allow rule-of­ thumb veneers to be layed up to within an arbitrary height limit of 4 metres, effectively a single storey. There is a latent demand for two-storey continuous cavity brick veneers, to be fixed to timber framing. To date, the degree of aseismic design expertise required, hampered by the lack of suitable wall ties and coupled with the additional effort necessary to access building permit approvals, have precluded such uses except for isolated instances. With the issuance of NZS 4210:1989[2] and the introduction of the La Palle flexible tie connector, this situation has been transformed. Utilizing the rules for materials and the guidelines for workmanship contained in this Code of Practice, two-storey designed timber structures supporting full height continuous cavity aseismic veneers can now be built to rational engineering standards. One such project is the topic of this article.