Phd in STRUCTURAL AND GEOTECHNICAL ENGINEERING

Thesis title: Geometry-based Assessment Techniques for Historical Masonry Structures: Numerical and Experimental Approach

Masonry, as one of the oldest construction materials, composes the vast majority of current buildings worldwide with a lot of them being part of the protected cultural heritage. Because of their high vulnerability to natural hazards, especially earthquakes, a lot of effort is still ongoing into solving the problem of accurately assessing them with appropriate and suitable tools, leaving this field still open for research. An ideology of geometry-based techniques is posed in the form of a research question with the intention of contributing through this thesis research. Its importance on an international dialogue and position within an interdisciplinary field is accommodated, always in respect towards international guidelines that bound structures of cultural importance. A comprehensive review proceeds regarding the treatment of masonry, covering its basic constituents, mechanical behavior, failure mechanisms and collapse hierarchy. A historical review on past approaches for the study of masonry are covered such that a link to the contemporary ones is realized. Contemporary methodologies are critically evaluated, highlighting their advantages and limitations within the modern framework of masonry structure analysis. Taking all of this into consideration the methodology proposed and used in this thesis is adjusted within this framework and in respect to the stance taken as the research statement. Methodology is then presented, starting with the perfect plasticity theory as the main theoretical and analytical framework of the limit analysis approach for masonry structures. Within the domain of limit analysis approaches, the in-house code ALMA (Analisi Limite Murature Attritive) is described and formulations for its implementation are presented. Enhancements to the code as novel contributions are then given, following with showcasing of its capabilities through illustrative examples. An experimental campaign utilizing tilting table tests is described, focusing on both small and large-scale experiments. Geometric and mechanical parameters are characterized, and numerical validations are conducted using the ALMA code. A case study comparing experimental results with existing literature concludes this section. The final chapter delves into numerical simulations investigating collapse mechanisms and multipliers in historical masonry structures. Parametric studies explore geometric and mechanical factors, including pointed and multi-ring arches, and the influence of different loading conditions on arches supported by piers. A stochastic approach is then employed to analyze randomized pier textures. Afterwards, a local strengthening strategy for historical masonry that incorporates geometry in the reinforcing mechanism, is proposed and studied. Insights from a case study on a monumental structure conclude the thesis, providing valuable findings for the field of masonry structure analysis.