University of Auckland, Department of Civil and Environmental Engineering


Unreinforced masonry (URM) was the most popular form of construction in New Zealand during the early 20th century, and therefore URM buildings form a large proportion of the country’s heritage building stock. To assist in the preservation of these heritage buildings, the New Zealand Society for Earthquake Engineering (NZSEE) published a guideline for detailed seismic assessment of URM buildings, which provided the recommended masonry material properties to be used for preliminary assessment. However, these recommended properties were based on limited experimental testing. Structural seismic designers have communicated the importance of accurate URM material property data in order to improve the accuracy of their seismic assessments, computer modelling and retrofit designs, which will result in a reduced cost to seismically protect these heritage buildings.
The work reported here focuses on the compressive strength and the stiffness of brick/mortar composites. Field samples were extracted from actual buildings to investigate the constituent material properties of New Zealand’s URM buildings and to confirm the relevance of findings derived from manufactured test samples. A predictive equation relating the brick, mortar and brick/mortar composite compressive strengths was developed and its suitability for New Zealand URM was assessed. The relationship between masonry compressive strength and the Modulus of Elasticity was also investigated and a provisional equation was developed. These predictive equations are intended as tools for structural seismic designers to predict masonry design material properties based upon the known brick and mortar properties.

Key words
unreinforced masonry, compressive strength, modulus of elasticity, field studies