Sydney’s St Mary’s Cathedral, the largest nineteenth century Gothic style cathedral, has finally reach completion with the construction of two spires, as depicted in the original plans that date back to the 1860’s.
Sinclair Knight Merz was commissioned to develop a Finite Element model of the 30 metre tall spire. The analysis exploited the symmetry of the structure and loading, and was based on a half symmetry finite element model. This strategy reduced the size of the model whilst retaining the required level of detail to accurately represent the physical structure and its stone intricacies.
The spire is constructed from high quality sandstone blocks that are secured to an internal steel seismic structure. The primary objective of this work was to determine the stresses in the stonework and highlight those areas that are more highly stressed under severe wind load conditions. This information was valuable in determining the optimum placement of stones so that stones of highest quality could be used where they are most needed, and stones of lesser quality could be used in less critical areas.
The construction phase of the spires required the operation of various pieces of mechanical equipment. Due to the importance and heritage classification of this building it was important to ensure that construction operations do not adversely affect the building. Sinclair Knight Merz undertook vibration monitoring to ensure the risk of structural damage was minimised.
The participation of Sinclair Knight Merz in this project provided our client with specialist experience in computer modelling, finite element analysis and field testing.