An Inventory of Unreinforced Masonry Churches in New Zealand (original) (raw)
Related papers
2006
Unreinforced Masonry (URM) was a very common building material in New Zealand during the later part of the 19 th and early part of the 20 th centuries, up until the 1931 Napier Earthquake. This paper outlines the prevalence and discusses typical details for unreinforced masonry in New Zealand. These findings are contextualised through comparison with the corresponding information from a selection of other seismically active countries. It has been found that New Zealand shares common URM structural details with Australia, the United States, Portugal and Italy. A lack of positive connection between URM walls and timber diaphragms is the most significant problematic detail common to all countries considered in this paper. The next most common detail was a lack of adequate connection between wall leaves, which can lead to out-of-plane failures under earthquake loading. New Zealand's building practices for URM construction are most closely aligned with those found in Australia and the United States.
Damage, casualty, and loss scenarios for New Zealand’s North Island churches
2018
The seismic vulnerability of 79 churches (65% timber, 16% reinforced concrete (RC), 13% unreinforced masonry (URM), and 6% concrete block) owned by the Anglican Diocese of Waikato and Taranaki, New Zealand has been assessed. Two types of seismic scenarios have been produced using the latest version of New Zealand’s National Seismic Hazard Model and RiskScape tool. The seismic scenarios produced are (1) the most likely events at 500, 1000and 2500year return periods for each church location, and (2) a series of large earthquakes affecting New Zealand’s North Island. Expected global damage levels for each church have been derived for each of the proposed scenarios using the macroseismic method, where the seismic hazard is defined by the intensity and correlated to post seismic damage. The macroseismic method used has been recently developed, and is specifically designed for New Zealand URM churches, based on a widely tested approach for European historical buildings. Preliminary vulner...
2012
Unreinforced masonry churches are particularly vulnerable to earthquakes because they are often deteriorated and damaged, they were built with comparatively low strength materials, they are heavy, and the connections between the various structural components are often insufficient to resist loads generated during earthquakes. A simplified method for seismic assessment of large span masonry churches is presented and data from 44 churches located in Italy, Portugal and Spain are used to provide lower bound limits for different simplified geometrical indexes. Subsequently, the proposed thresholds are validated with data from the 2010-2011 Canterbury earthquakes, including 48 clay brick and stone unreinforced masonry churches. Finally, data collected for 40 unreinforced masonry churches in Wellington and Dunedin are used to identify churches in these cities requiring priority detailed seismic evaluation.
Unreinforced stone masonry buildings in New Zealand: Inventory and material characterisation
The high seismic vulnerability of unreinforced stone masonry (URM) buildings was once again demonstrated in the recent Canterbury earthquakes (2010)(2011). The shortage of knowledge about New Zealand historic URM buildings, and about techniques for their conservation, led to numerous losses, both in terms of lives and architectural heritage. Almost all URM buildings in New Zealand were constructed between 1860 and 1910, typically in regions where natural stone (in particular basalt, schist and limestone) was sourced from local quarries, fields and rivers. There are estimated to be approximately 688 URM buildings in New Zealand, with most being a potential earthquake risk. As a first step, an inventory of the URM buildings of New Zealand was compiled, listing location, construction details and architectural configuration. A further development was the inspection of representative case study buildings, where architectural characteristics and extracted material samples were obtained. Compressive tests and petrographical analyses were undertaken on natural stone specimens, while compressive strength and mineralogical composition were determined for mortar samples. The aim of the study reported herein was to acquire a thorough understanding of the mechanical and physical properties of these URM buildings in order to assess seismic vulnerability factors and potential seismic improvement solutions.
The damage assessment of monumental buildings after numerous seismic events in different countries has systematically highlighted the vulnerability of monumental structures, in particular churches, and the critical importance of reducing their risk from an economic, cultural and social point of view. This evidence has been highlighted, once again, by the Canterbury earthquake sequence, that dramatically affected New Zealand in 2010-2011. Within this context, detailed analysis is reported of the earthquake-induced damage to a stock of 48 unreinforced masonry (URM) churches located in the Canterbury Region and the seismic vulnerability analysis of a wider stock of 293 URM churches located all around New Zealand. The final aim of the study was the collection of meaningful data and evidence to support mitigation strategies and policies for reducing the seismic risk for churches. To support this aim, new tools and forms were developed that are specifically oriented to facilitate analysis of the features of New Zealand churches. The computation of a new damage grade is proposed, assessed as a proper combination of the damage level to each macroelement, as a step towards the definition of a New Zealand specific damage survey form and the preliminary derivation of empirical fragility curves. For the vulnerability analysis several indicators were selected, which are related to easily detectable structural details and geometric dimensions. The collection of such data for the larger set of churches (293) provided an overview of structural features of this class in New Zealand and constitutes a useful basis for evaluating the potential impact of future seismic events.
An inventory of unreinforced load-bearing stone masonry buildings in New Zealand
Almost all unreinforced stone masonry (URSM) buildings in New Zealand were constructed between 1860 and 1910, typically in regions where natural stone was sourced from local quarries, fields and rivers. These buildings form an important part of the country's architectural heritage, but the performance of URSM buildings during earthquake induced shaking can differ widely due to many aspects related to the constituent construction materials and type of masonry wall cross-section morphology. Consequently, as a step towards gaining greater knowledge of the New Zealand URSM building stock and its features, an exercise was undertaken to identify and document the country-wide URSM building inventory. The compiled building inventory database includes: (i) general building information, such as address, building owner/tenant and building use; (ii) architectural configuration, such as approximate floor area, number of storeys, connection with other buildings, plan and elevation regularity; and (iii) masonry type, such as stone and mortar types, wall texture and wall cross-section morphology. From this exercise it is estimated that there is in excess of 668 URSM buildings currently in existence throughout New Zealand. A large number of these vintage URSM buildings require detailed seismic assessment and the implementation of seismic strengthening interventions in order to conserve and enhance this component of New Zealand's cultural and national identity. The entire stock of identified buildings is reported in the appended annex (688 total), including 20 URSM buildings that were demolished following the Canterbury earthquake sequence.
Journal of Earthquake Engineering, 2016
The 2010-2011 Canterbury earthquake sequence caused extensive damage to unreinforced masonry churches. A sample of 80 affected buildings was analysed and their performance statistically interpreted. Structural behaviour is described in terms of mechanisms affecting the so-called macro-elements, and damage probability matrices are computed. Regression models correlating mean damage level against macroseismic intensity are also developed for all observed mechanisms, improving the initial simple-linear formulations through use of multiplelinear regressions accounting for vulnerability modifiers, whose influence is evaluated via statistical procedures. Results presented herein will support the future development of predictive tools for decision-makers, also contributing to seismic vulnerability mitigation at a territorial scale.