Architectural Considerations for the Seismic Retrofit of URM Buildings
Principal Researcher: Associate
Professor Jason Ingham
Students involved: Alistair
Russell, Cass Goodwin
The historic value of the surviving unreinforced masonry (URM) building stock in New Zealand is increasingly becoming recognised and protected from alteration by heritage legislation and organisations. Many of these buildings have significant historic value and contribute greatly to the character of our cities. The seismic retrofit project seeks simple and effective ways to analyse and strengthen unreinforced masonry buildings to safeguard both human life and the structures themselves from loss during an earthquake.
There is a danger that if insufficient consideration is given to the historic and architectural qualities of these buildings, the retrofit may visually damage them or remove important historic material. This may result in a safer building, but one which is detrimentally affected overall.
Careful thought needs to be given to the extent, type, and placement of any strengthening work. The goal is to minimise adverse effects on the fabric of the building and on the spaces in and around it. There are several principles which should be given priority:1
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Only do as much as is necessary, and as little as possible. The less interference with the original fabric of the building, the better.
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Strengthening work should be reversible. This allows for the possibility of the use of improved strengthening systems in the future, and for removal of additional materials during future restoration or adaptive reuse without damage to the original fabric.
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One should always gain knowledge of the important characteristics of a building.
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Any strengthening work should respect the integrity and character of a heritage building.
The aims of this study are to:
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Explain the meaning of heritage, and the history and theory which have formed current attitudes to preservation.
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Analyse available URM strengthening methods and comment on their appropriateness with reference to preservation ideals.
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Present case studies of unstrengthened URM buildings, highlighting important characteristics, and how to identify significant architectural and historic features.
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Present case studies of previously strengthened URM buildings, highlighting the varying success of strengthening techniques, and commenting on their appropriateness.
The desired outcome is a legible document which will allow the reader to understand the important aspects of heritage preservation, and be able (to identify) elements of a building which contribute to architectural character. Further, the reader should be better informed of what constitutes good strengthening techniques, and why.
A retrofit project may need to consider the conservation of:
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The building form - the external geometry and arrangement of elements which identify the building as unique. I.e. the way it looks.
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The physical materials which make up the building.
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Surface finishes and materials – including colour, patterns, texture, and shape.
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The interior of the building – particularly the internal spaces, and the relationship between these spaces.
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The external spaces - how the building relates to its immediate surroundings.
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The history and various uses of the building.
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Construction techniques.
A strengthening element does not necessarily have to be hidden within the existing fabric of the building, but consideration does need to be given to the impact (visual and otherwise) that it may have.
For further reading see: www.historic.org.nz and www.icomos.org.nz
The New Zealand Historic Places Trust has issued a guide on earthquake strengthening of earthquake prone buildings:
http://www.historic.org.nz/heritage/localgov_advocacy.html#guide
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Exterior wall of Charter House - 54-58 Customs St (Auckland) |
Dome on top of Courtville Apartments - (Auckland) |