A Computational Modelling Strategy For Historic Masonry Structures

The inherent complexities of masonry structures make prediction of their life expectancy very challenging. Moreover, the combined actions of time-dependent defects in structures under sustained stress greatly influence the stability and safety of these structures. Consequently, it is very difficult to identify and simulate such defects in a realistic manner without the knowledge of, and access to, the mechanical properties of the constituent materials, the construction details and the long-term effects of weathering. As a result, it is difficult to make any accurate predictions of the long-term deformation, stability and safety of the historic masonry.
This thesis describes a computational modelling strategy for the structural analysis of historic masonry structures subjected to static loading. The modelling strategy includes loss of section effects (caused by freeze-thaw action, salt crystallisation damage and exfoliation); creep and creep-induced cracking. The proposed strategy also includes the effects of reconstruction and repair. This approach should help those responsible for the operation and management of historic masonry structures to make better informed decisions about safety, stability and maintenance in the future.
The computational strategy employs the finite element method, using an elastic-plastic constitutive law for masonry, to develop a computational tool using Abaqus software. The tool was used to predict the structural response of a tall solid brickwork pier of a multi-span Victorian former railway viaduct in Whitby, Northern England. The pier is known to have suffered from a loss of section caused by frost damage and parts of it have been repaired with replacement brickwork. The pier also has clear visible signs of vertical cracking in the regions above its foundation. As there are no signs of settlement, it has been assumed that these cracks have been induced by long-term creep effects. In spite of the inherent variability of masonry and the uncertainties in the material parameters and mechanical behaviour, quite good correlation was obtained between the crack patterns in the pier predicted using the computational tool and those observed in the real viaduct, thus, validating the strategy. The findings of this research allow for simple, flexible and reliable structural analysis of present state and predictions of future conditions of historic masonry structures.