|Structural Enhancement of St Georges Cathedral, Perth
|Keywords: Strengthening of heritage building for earthquake, Minimum visual intrusion of remedial works
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St George's Anglican Cathedral was built between 1883 and 1903 at a cost of £17,000. It is located in the heart of Perth City. The structure consists of a timber roof and walls of brick and stone. Over the years there has been gradual deterioration of the building fabric and structure.
Problems include cracked, overstressed and unstable walls, split timber and failed timber joints. Since 1932 bell ringers have expressed concerns for safety due to bell tower movement when bells are rung. On one occasion bricks fell into the Cathedral during bell ringing. In 1966 concerns were raised about continuing erosion of brickwork. CSIRO scientists estimated the building's life at 20-30 years.
The brief to Ian Maitland's company MCSE is:
· To strengthen the building to comply with earthquake code AS3826.
· An absolute minimum of remedial works to be visible.
· To prolong the life of the building.
· To complete the work at minimal cost.
· Use of existing ceilings and new ply sheeting to act as structural membranes.
· A variety of roof to wall connections.
· Twisted stainless steel rods to reinforce brickwork.
· Strengthening of timber roof trusses.
· Cantilever buttresses to stabilise gable walls.
· Tie rods with decorative connectors over the crossing.
Starting in 2002 with no original drawings and little recorded history, MCSE undertook a comprehensive process of a building condition audit, data review, information gathering, material testing, structural analysis and design, remediation documentation and contract administration during construction. The project was completed in September 2007 at a total cost of $5.4M of which $2.0M was for structural enhancement.
REFERENCE: Maitland, I.B.G. 2007 Structural Enhancement of St George's Cathedral Perth. Fourteenth National Engineering Heritage Conference Perth, Australia, 18 September - 21 September 2007. The Institution of Engineers Australia: Conference Papers.