Stability of Multi-Wythe Historic Stone Masonry Walls
Abstract
The Prince of Wales Fort was constructed in the 18th century in Churchill, Manitoba, in the Vauban style, being the most northerly construction of its kind, and intended to secure the fur trade in northern Canada for the British. The perimeter walls consist of two wythes of cut ashlars and a rubble core. Annual maintenance has become necessary to maintain this fort as a heritage structure with the rate of deterioration accelerating in the last decade, requiring the initiation of a large restoration project. This project involves rebuilding of damaged wall sections. During the course of the work, sections of wall thought to be in good condition were found to be undergoing significant displacements and were added to the project scope. Subsequently a more thorough understanding of the causes of failure was desired so work could be done to prevent further problem areas.
To test the hypothesis that failure was initiated by degradation of the mortar within the walls, micro-modelling using both the Discrete (DEM) Finite Element (FEM) and Random Finite Element (RFEM) methods was implemented. The micro-modelling approach used in the DEM involved simplified geometry; the model was used to determine if a transition could be made from instability to stability for a given section by increasing the bond alone. The FEM used a detailed micro modelling approach, modelling both the units and mortar using continuum elements and modelling the unit mortar interface with a defined contact. Using the FE method a parametric analysis of both material strength and bond strength of the mortar within the wall sections was completed. The RFEM was used to randomize the material properties, which had been parametrically evaluated through the FEM.
The research identifies a new general mechanism of failure for multi-wythe masonry walls, and their susceptibility to environmental conditions. The numerical results predicted that the stone-grout bond was the most critical parameter in the proposed intervention, and that in the grouted wall sections, collapse would be avoided and lateral displacements stabilized with the proposed treatment.
Description
Keywords
Engineering--Civil, Materials Science
Citation
Isfeld, A. (2016). Stability of Multi-Wythe Historic Stone Masonry Walls (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/27864