Antonino Iannuzzo

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Iannuzzo

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Antonino

ORCID

0000-0002-6633-149X

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Publications 1 - 10 of 15

Parametric Stability Analysis of Groin Vaults
Maia Avelino, Ricardo; Iannuzzo, Antonino; Van Mele, Tom; et al. (2021)
Applied Sciences
This paper presents a parametric stability study of groin, or cross vaults, a structural element widely used in old masonry construction, particularly in Gothic architecture. The vaults’ stability is measured using the geometric safety factor (GSF), computed by evaluating the structure’s minimum thickness through a thrust network analysis (TNA). This minimum thickness is obtained by formulating and solving a specific constrained nonlinear optimisation problem. The constraints of this optimisation enforce the limit analysis’s admissibility criteria, and the equilibrium is calculated using independent force densities on a fixed horizontal projection of the thrust network. The parametric description of the vault’s geometry is defined with respect to the radius of curvature of the vault and its springing angle. This detailed parametric study allows identifying optimal parameters which improve the vaults’ stability, and a comprehensive comparison of these results was performed with known results available for two-dimensional pointed arches. Moreover, an investigation of different force flows represented by different form diagrams was performed, providing a better understanding of the vaults’ structural behaviour, and possible collapse mechanisms were studied by observing the points where the thrust network touches the structural envelope in the limit states. Beyond evaluating the GSF, the groin vault’s stability domain was described to give additional insights into the structural robustness. Finally, this paper shows how advances in equilibrium methods can be useful to understand and assess masonry groin vaults.
Understanding the rigid-block equilibrium method by way of mathematical programming
Kao, Gene Ting-Chun; Iannuzzo, Antonino; Coros, Stelian; et al. (2021)
Proceedings of the Institution of Civil Engineers - Engineering and Computational Mechanics
This paper discusses and extends some main features of the rigid-block equilibrium (RBE) method. RBE is a numerical approach that frames the equilibrium problem of rigid-block assemblies as an optimisation problem to compute possible internal and equilibrated singular stress states. The contact between blocks is considered having a finite friction capacity and the unilateral behaviour is modelled through a penalty formulation. In particular, the penalty formulation widens the standard admissible solution space of compressive-only forces by allowing for tensile forces appearing on potentially unstable regions. The RBE objective function minimises the interface forces whereas the constraints are linear functions enforcing the static equilibrium of the whole assembly. In this paper, along with the original quadratic objective function, the authors propose a linear function to illustrate and explore the role played by both the nodal forces and the interface resultants. Moreover, the authors show how RBE can be used to explore different admissible internal stress states - for example, due to increasing, static, horizontal actions.
A new numerical limit analysis-based strategy to retrofit masonry curved structures with FRCM systems
Fugger, Rebecca; Maia Avelino, Ricardo; Iannuzzo, Antonino; et al. (2022)
ECCOMAS Congress 2022 - 8th European Congress on Computational Methods in Applied Sciences and Engineering
In most historic masonry structures, curved geometries, such as arches or vaults, are key structural components to the overall building stability. Therefore, it is crucial to assess their safety level with respect to changes in the boundary conditions (increased loads or settlements). If the safety level of the structure needs to be enhanced, a strategy to intervene and retrofit structural members is represented by the use of Fabric Reinforced Cementitious Matrix (FRCM) systems. These types of externally bonded composite materials, made of high-strength textiles embedded in inorganic matrices, are proven to be a particularly advantageous strengthening solution for curved masonry structures. Even though limit analysis approaches such as Thrust Network Analysis (TNA) have been widely used to assess structural stability, their use in a retrofitting framework is seldom explored. This paper proposes an automated procedure to design the FRCM reinforcement required in masonry structures based on an initial TNA assessment analysis. To perform these analyses, a nonlinear programming problem is implemented and solved to compute the minimum reinforcement required for stability. These quantities are then used to design the FRCM reinforcement according to existing regulations. Finally, the load-bearing capacity of the reinforced structure can be re-evaluated for different load cases ensuring that the structure is safe. The effectiveness of the proposed approach is benchmarked against laboratory tests and demonstrated on arched structures.
When cracks are (not) a structural concern: the case of 'Giovanni Vinciguerra' School in Anagni
Ferrero, Chiara; Cusano, Concetta; Yavuzer, Mehmet Nuri; et al. (2022)
International Journal of Masonry Research and Innovation
This paper presents the structural assessment of a portion of 'Giovanni Vinciguerra' School, located in the municipality of Anagni, Italy. In 2009, the presence of some cracks in the vaults of the basement led the authorities to close the building and declare it not usable. In this work, firstly a proper knowledge of the history, geometry and structural configuration of the school was achieved by means of bibliographic research, laser-scanner survey and visual inspections. During onsite inspections, the damage observed was also surveyed and mapped in detail. Then, structural analysis applying graphic statics and inverse piecewise rigid displacement (PRD) analysis was carried out with the aim to identify the causes of damage and evaluate the residual structural safety of the building. The results obtained allowed to prove that the structure is safe despite the occurrence of some damage in the basement.
New strategies to assess the safety of unreinforced masonry structures using Thrust Network Analysis
Maia Avelino, Ricardo; Iannuzzo, Antonino; Van Mele, Tom; et al. (2021)
12th International Conference on Structural Analysis of Historical Constructions (SAHC 2021)
This work develops new strategies to robustly apply Thrust Network Analysis (TNA) for the assessment of unreinforced masonry (URM) structures studied within the frame of limit analysis. It formulates and solves a nonlinear optimisation problem on thrust networks considering relevant constraints for the assessment of URM structures. Geometrical and force constraints are include such as the consideration of the structural envelope and bounds on the reaction forces. The objective functions studied correspond to the minimum and maximum horizontal thrusts of the vaults. To evaluate the level of stability of an existing structure, this work develops a methodology to estimate the geometric safety factor (GSF) and the minimum thickness of masonry vaults by solving sequential optimisation problems for increasingly tightened geometrical bounds. This procedure is implemented in the open-source, Python-based tool, named compas_tna and illustrated here on two- and three-dimensional applications that are relevant for the structural analysis of historical constructions.
An energy-based strategy to find admissible thrust networks compatible with foundation settlements in masonry structures
Maia Avelino, Ricardo; Iannuzzo, Antonino; Van Mele, Tom; et al. (2022)
Mechanics Research Communications
This paper presents an energy-based methodology to compute internal stress states compatible with foundation settlements in masonry structures. The method is based on the application of Thrust Network Analysis (TNA). TNA is a lower-bound method that searches for admissible force networks in masonry structures by solving a constrained nonlinear optimisation problem (NLP) in which constraints enforce the limit analysis’ admissibility criteria. In this paper, the objective function minimises the complementary energy, which directly considers prescribed foundation displacements. This minimum energy criterion allows selecting among the infinite admissible stress states, the ones compatible with the settlements, suggesting potential crack regions at the onset of the motion. Application to general two- and three-dimensional masonry structures under vertical and horizontal loads are presented. The method has the potential to link internal stress states to boundary displacements and, thus, give mechanical meaning to typical crack patterns observed in masonry structures.
Coupled Rigid-Block Analysis: Stability-Aware Design of Complex Discrete-Element Assemblies
Kao, Gene Ting-Chun; Iannuzzo, Antonino; Thomaszewski, Bernhard; et al. (2022)
Computer Aided Design
The rigid-block equilibrium (RBE) method uses a penalty formulation to measure structural infeasibility or to guide the design of stable discrete-element assemblies from unstable geometry. However, RBE is a purely force-based formulation, and it incorrectly describes stability when complex interface geometries are involved. To overcome this issue, this paper introduces the coupled rigid-block analysis (CRA) method, a more robust approach building upon RBE's strengths. The CRA method combines equilibrium and kinematics in a penalty formulation in a nonlinear programming problem. An extensive benchmark campaign is used to show how CRA enables accurate modelling of complex three-dimensional discrete-element assemblies formed by rigid blocks. In addition, an interactive stability-aware design process to guide user design towards structurally-sound assemblies is proposed. Finally, the potential of our method for real-world problems are demonstrated by designing complex and scaffolding-free physical models.
Modelling imperfections in unreinforced masonry structures: Discrete element simulations and scale model experiments of a pavilion vault
Dell'Endice, Alessandro; Iannuzzo, Antonino; DeJong, Matthew J.; et al. (2021)
Engineering Structures
The structural assessment of doubly-curved vaulted masonry structures, such as pavilion vaults, poses challenges specific to their high degree of indeterminacy. Two-dimensional equilibrium analysis methods may provide a lower bound of load or displacement capacity, but they do not accurately describe the three-dimensional (3D) behaviour of these structures, particularly when shear deformation (e.g. sliding) is important. Therefore, discrete element modelling (DEM) methods, which can effectively simulate 3D load re-distribution, have been used to investigate support displacement capacity and corresponding 3D collapse mechanisms. DEM analyses are usually conducted on perfect digital geometries. Meanwhile, both real structures and small-scale physical models have implicit assembly and fabrication imperfections, which may significantly alter their response. The present paper aims to investigate the influence of geometrical and mechanical imperfections by comparing DEM analyses with the results obtained from tests on a scale model. In particular, a new method to simulate imperfections within the DEM framework is proposed, and a DEM parametric analysis is compared to the measured behaviour of a 3D-printed scale model of a pavilion (or cloister) vault on spreading supports. The influence of both mechanical imperfections and geometrical imperfections, due to element geometry deviations or imprecision of the assembly process, have been investigated. Based on these analyses, the three-dimensional behaviour of a pavilion vault subjected to horizontal displacement of the supports is described, and the variability of results due to imperfections is demonstrated. A good agreement between DEM analyses and 3D-printed scale model tests is achieved, in terms of crack patterns and mechanisms. Geometrical imperfections did change the load paths within the vault, as expected, and also influenced the displacement capacity.
A continuous energy-based numerical approach to predict fracture mechanisms in masonry structures: CDF method
Iannuzzo, Antonino; Block, Philippe; Angelillo, Maurizio; et al. (2021)
Computers & Structures
In the present paper, we propose the Continuous Displacement for Fracture (CDF) method, a continuous energy-based numerical approach to find mechanisms and crack patterns exhibited by 2D masonry structures subjected to given loads and settlements. The structure is modelled through the normal, rigid, no-tension material, and the equilibrium problem is solved as the minimum of the total potential energy (TPE). With the CDF method the solution is sought in the space of continuous functions. The CDF performances are compared and illustrated against the PRD approach that finds the TPE minimum in the space of small, piecewise-rigid displacements. The CDF method is displacement-based approach, allowing for a direct control of the effects of foundation settlements. Some problems are proposed to benchmark the methodology against both PRD and analytical solutions to also clearly illustrate its peculiarities. Finally, its use and potentials are benchmarked and compared on a case study. CDF provides results in good agreement with both the PRD approach and another more sophisticated model. The main outcome is that, although more computationally cumbersome, CDF is mesh independent and perfectly captures a clear subdivision of the structural domain into macro-regions behaving as rigid or quasi-rigid bodies.
Influence of settlements and geometrical imperfections on the internal stress state of masonry structures
Dell'Endice, Alessandro; Iannuzzo, Antonino; Van Mele, Tom; et al. (2021)
12th International Conference on Structural Analysis of Historical Constructions (SAHC 2021)
Since a few decades, the Discrete Element Modelling (DEM) method has been adopted by many authors as a reliable tool for the structural assessment of unreinforced masonry (URM) structures. In this paper, through compas_dem and using 3DEC by Itasca as a solver in the background, we investigate the mechanical behaviour of a three-dimensional URM structure combining the effects of foundation displacements and geometrical imperfections. For this purpose, we consider three different models of the above-mentioned structure. The first one is a perfect digital model, while in the other remaining two models, random geometrical imperfections are applied to the perfect model in order to investigate their influence. After post-processing the 3DEC results, the influence of the applied vertical settlement and geometrical imperfections is explored in terms of crack pattern/mechanism, internal stress states, and the thrust exerted on the supports. The aim of this paper is not to find the actual stress state of the highly indeterminate structure, but to investigate the role played by the combined effects of foundation displacement and geometrical imperfections on the internal stress state.

Publications 1 - 10 of 15

Antonino Iannuzzo

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