Following the devastating 1931 Hawke's Bay earthquake, buildings in Napier and surrounding areas in the Hawke's Bay region were rebuilt in a comparatively homogenous structural and architectural style comprising the region's famous Art Deco stock. These interwar buildings are most often composed of reinforced concrete two-way space frames, and although they have comparatively ductile detailing for their date of construction, are often expected to be brittle, earthquake-prone buildings in preliminary seismic assessments. Furthermore, the likelihood of global collapse of an RC building during a design-level earthquake became an issue warranting particular attention following the collapse of multiple RC buildings in the February 22, 2011 Christchurch earthquake. Those who value the architectural heritage and future use of these iconic Art Deco buildings - including building owners, tenants, and city officials, among others - must consider how they can be best preserved and utilized functionally given the especially pressing implications of relevant safety, regulatory, and economic factors. This study was intended to provide information on the seismic hazard, geometric weaknesses, collapse hazards, material properties, structural detailing, empirically based vulnerability, and recommended analysis approaches particular to Art Deco buildings in Hawke's Bay as a resource for professional structural engineers tasked with seismic assessments and retrofit designs for these buildings. The observed satisfactory performance of similar low-rise, ostensibly brittle RC buildings in other earthquakes and the examination of the structural redundancy and expected column drift capacities in these buildings, led to the conclusion that the seismic capacity of these buildings is generally underrated in simple, force-based assessments.
The M7.1 Darfield earthquake shook the town of Christchurch (New Zealand) in the early morning on Saturday 4th September 2010 and caused damage to a number of heritage unreinforced masonry buildings. No fatalities were reported directly linked to the earthquake, but the damage to important heritage buildings was the most extensive to have occurred since the 1931 Hawke‟s Bay earthquake. In general, the nature of damage was consistent with observations previously made on the seismic performance of unreinforced masonry buildings in large earthquakes, with aspects such as toppled chimneys and parapets, failure of gables and poorly secured face-loaded walls, and in-plane damage to masonry frames all being extensively documented. This report on the performance of the unreinforced masonry buildings in the 2010 Darfield earthquake provides details on typical building characteristics, a review of damage statistics obtained by interrogating the building assessment database that was compiled in association with post-earthquake building inspections, and a review of the characteristic failure modes that were observed.
In the early morning of 4th September 2010 the region of Canterbury, New Zealand, was subjected to a magnitude 7.1 earthquake. The epicentre was located near the town of Darfield, 40 km west of the city of Christchurch. This was the country’s most damaging earthquake since the 1931 Hawke’s Bay earthquake (GeoNet, 2010). Since 4th September 2010 the region has been subjected to thousands of aftershocks, including several more damaging events such as a magnitude 6.3 aftershock on 22nd February 2011. Although of a smaller magnitude, the earthquake on 22nd February produced peak ground accelerations in the Christchurch region three times greater than the 4th September earthquake and in some cases shaking intensities greater than twice the design level (GeoNet, 2011; IPENZ, 2011). While in September 2010 most earthquake shaking damage was limited to unreinforced masonry (URM) buildings, in February all types of buildings sustained damage. Temporary shoring and strengthening techniques applied to buildings following the Darfield earthquake were tested in February 2011. In addition, two large aftershocks occurred on 13th June 2011 (magnitudes 5.7 and 6.2), further damaging many already weakened structures. The damage to unreinforced and retrofitted clay brick masonry buildings in the 4th September 2010 Darfield earthquake has already been reported by Ingham and Griffith (2011) and Dizhur et al. (2010b). A brief review of damage from the 22nd February 2011 earthquake is presented here
