Underpinning Christ Church Cathedral


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Title: Underpinning Christ Church Cathedral

Author(s): Dirk Dressel, Joseph Gallacio, and Shahbaz Mavaddat

Publication: Concrete International

Volume: 13

Issue: 10

Appears on pages(s): 39-43

Keywords: caissons; foundations; masonry; post-tensioning; religious buildings; settlement (structural); Construction

Date: 10/1/1991

Christ Church Cathedral is an Anglican church situated in the heart of downtown Montreal. Constructed in 1859, it is a perfect example of English neo-gothic architecture, characterized by stone load-bearing walls and columns, a central tower with a spire rising 220 feet (67 m) above the main church floor, and stained glass windows. To utilize the space below the church as an integral part of an overall retail development plan, a method of transferring the existing foundation loads to new foundations was developed. Weighing approximately 18,000 tons (16,345 Mt) and spread over some 16,000 square feet (4900 square metres), the entire church structure, including the tower and spire, was underpinned by means of post-tensioned concrete beams and founded on new caissons. It was essential that the Cathedral remain operational during the entire period of construction.