New Zealand's unreinforced masonry buildings : facing up to the earthquake.

Abstract

The damage caused by the 2011 Christchurch earthquake has led to the introduction of compulsory seismic strengthening legislation for all unreinforced earthquake-prone masonry buildings (URM) within New Zealand. The legislation, passed in 2013, requires all such URM commercial, multi-unit and multi-storey residential buildings to be upgraded and strengthened to a minimum of 34% or more of the New Building Standard, irrespective of the earthquake zone within which they are located. Buildings so designated and in high earthquake zones will have a very limited time bring their buildings into line with these requirements. The proposal particularly affects old URM buildings. Some of these are buildings have a declared heritage value, many do not. Most were built around the turn of the twentieth Century. Together they make up a considerable portion of many small town commercial precincts. The legislation affects all parts of New Zealand, regardless of the particular region’s exposure to earthquake risk.

The paper will background the current legislation, compare international legislation and study the financial effects of the legislation, case studying buildings within two distinct seismic zones. The findings suggest that where the cost of the upgrade puts the viability of the building as a rental investment at risk, the owner will most likely adopt demolition is the only feasible outcome. This could have far-reaching implications for the wellbeing of many small towns within New Zealand. An alternative strategy is examined and assessed