Dr Marco Francesco Funari

In this paper, we propose an optimised multi-level method to efficiently account for the actual masonry pattern in the pushover analysis of historic masonry structures. The method begins with a rigid block-based limit analysis accounting for the actual masonry pattern to identify realistic failure mechanisms. Next, macro-blocks that outline the failure mechanism are identified using a novel optimised procedure that includes a heuristic search, which minimises the number of blocks and non-linear interfaces in the subsequent analyses. Subsequently, macro-blocks are modelled as homogeneous material interacting via cohesive-frictional interfaces in a finite element environment where pushover analysis produces force–displacement curves. Validation against various structural benchmarks with regular and irregular masonry patterns and different loading configurations demonstrates the method’s accuracy and competitiveness compared to micro-modelling approaches. Results show up to a 90% reduction in computational time and the number of blocks, with a maximum difference of about 5% in numerical prediction of force capacity.

•Generative programming enables the creation of digital representations of built cultural heritage.•The Vesta temple in Tivoli was chosen as a case study for this research.•Francesco Piranesi's 18th-century etchings informed the layout and modular design.•The workflow allows the generating of exportable files compatible with simulation software.•Parametric modelling provides high reusability and adaptability of algorithms. This paper presents a novel method for generating geometric models of architectural heritage in the absence of a digital survey. The method employs a Generative Programming (GP) algorithm for geometric model generation, with the Temple of Vesta in Tivoli chosen as a case study. Francesco Piranesi's 18th-century etchings are utilised as references to identify the architectural layout and modularity. The effectiveness of the proposed generative workflow is highlighted through its time efficiency and the reusability of the algorithm. The workflow includes the capability to generate an export file suitable for structural simulation software packages. The generated geometric model is then used to conduct nonlinear dynamic analysis using a concurrent continuous/block-based approach within a Finite Element environment. The simulations are performed with the structure in its current state and do not account for retrofitting interventions, i.e. anchorages and tie rods are not taken into account. The numerical model reveals how local failure mechanisms of columns and entablature affect the structural safety of the Vesta temple.

A considerable amount of historic masonry structures (HMS) are composed of irregular stone. However, few studies have systematically investigated the influence of masonry patterns (or masonry unit arrangements) on structural behaviour. The main difficulty stems from the pattern acquisition and the definition of adequate parameters that correlate the pattern with the structural behaviour. To this aim, this paper presents a stochastic 2D coursed-rectangular masonry pattern generator that incorporates geometric quality indexes (QI) to generate patterns with consistent masonry quality and structural behaviour. The generator's input parameters separately consider the available stone units and the "virtual mason"'s skill level to cover the range of possible pattern qualities. Finally, micro limit analysis simulations show how deviation from the "rules of art" reduces strength capacity by up to 30%. Furthermore, it has been discussed how masonry patterns generated with selected QI-s show consistent structural behaviour, e.g. reducing the coefficient of variation of the strength capacities by 15%.

This work examines the environmental impact of low-carbon concrete that incorporates supplementary cementitious materials (SCMs). After reviewing near-zero carbon SCMs and low-carbon concrete, a life cycle assessment (LCA) was undertaken for concrete mix designs with normal-to-high compressive strengths, incorporating limestone and fly ash as cement replacements. The analysis includes relevant region-specific life cycle inventory parameters for raw materials, energy production, and transportation. A comparative assessment between embodied carbon emissions and the material mechanical performance is then made. The results of this paper indicate that incorporating limestone and fly ash in concrete can reduce carbon emissions, yet at a proportional decrease in mechanical properties compared to conventional cement concrete. The combination of cement and fly ash produced, on average, a higher strength concrete by 20.5% and lower CO2-eq values by 21.1% when compared to limestone cement blends. The CO2-eq emissions associated with transportation of the main constituents for concrete production were on average below 4% of the total CO2-eq per mix. In addition to eco-mechanical quantitative assessments, the study offers insights and recommendations for the development of concrete materials considering global resource availability of near-zero carbon concrete constituents.

A mechanistic model is presented for the strength prediction of squared columns made of masonry with a periodic arrangement and strengthened with a fibre–polymer composite jacketing. The formulation is based on an incremental plasticity theory that relies on equilibrium, compatibility, and kinematic equations. The strength domain of brick units and mortar joints is bounded by a multi-surface yield criterion: a Mohr–Coulomb strength domain with a linear cap in compression and a Rankine cut-off in tension. An elasto-plastic response with limited ductility is assumed for both masonry components. Differently, the FRP response is assumed elastic with a brittle failure governed by a limited tensile strain. Phenomenological-based assumptions are undertaken and justified. Details are also provided for the computational implementation of the procedure. The model accuracy is validated against experimental data on masonry squared columns and compared with existing standard-based formulas. Results demonstrate it provides real-time and accurate compressive strength solutions for squared masonry columns with or without a polymer-based wrapping and yet requiring few input parameters for the masonry constituents and reinforcement.

This paper presents numerical investigations using the mesoscale approach coupled with the discrete macro-element approach for masonry structures, i.e., each macro-element represents a single unit stone. At first, parametric analyses are performed on a U-shape masonry prototype made with stone. Nonlinear static analyses are performed to investigate parameters that affect the results when a mesoscale masonry pattern representation is adopted. Results demonstrate how mesoscale representation is a powerful alternative to model unreinforced masonry structures within a discrete macro-element approach (particularly if compared with classic homogeneous FE methodologies). However, one of the main challenges in using the mesoscale approach for the structural assessment of masonry buildings, made with stones having different dimensions, is the unit by unit description. The complexity of the problem, and the amount of information needed, usually preclude the study of these structures deterministically. To this end, a digital tool to generate randomised masonry patterns using a few input parameters is proposed. A box structure is adopted as parent geometry, and ten masonry patterns with different degrees of randomness are investigated by performing nonlinear static and dynamic simulations. The outcomes focus on the influence of masonry patterns and demonstrate how irregularity of units can affect the structural response leading to a reduction in terms of strength and ductility if compared to regular distribution of masonry units.

An analysis to show the capability of moving mesh strategy to predict dynamic crack growth phenomena in 2D continuum media is proposed. The numerical method is implemented in the framework of the finite element method, which is coupled with moving mesh strategy to simulate the geometry variation produced by the crack tip motion. In particular, a computational procedure based on the combination of Fracture Mechanics concepts and Arbitrary Lagrangian-Eulerian approach (ALE) is developed. This represents a generalization of previous authors' works in a dynamic framework to propose a unified approach for predicting crack propagation in both static and dynamic frameworks. The crack speed is explicitly evaluated at each time step by using a proper crack tip speed criterion, which can be expressed as a function of energy release rate or stress intensity factor. Experimental and numerical results are proposed to validate the proposed approach. Mesh dependence problem, computational efficiency and numerical complexity arc verified by comparative results.

A digital tool is presented and made available for the rapid structural assessment of historic masonry domes. It is especially suited for masonry domes that present long meridian cracks; ergo partitioned slices governed by a pushing failure mode. The proposed procedure considers a Heyman's no-tension mechanical model that has been implemented within a user-friendly visual programming environment. The numerical approach includes parametric modelling of the failure mechanism that allows exploring the domain of solutions using the kinematic theorem of limit analysis. A heuristic search method is subsequently adopted to refine the geometry of the collapse mechanism and to compute the value of the horizontal trust. Validation of the results has been achieved considering St. Peter's dome. As reported in the literature, the behaviour of this dome shifted from a rigid shell-type - stiffened by hoop stresses - towards a pushing type of dome partitioned by long meridian cracks. Unlike time-consuming and advanced methods of analysis, the present procedure allows the users to perform a structural assessment of a historic masonry dome in a few seconds and offers the possibility of including: (i) the dome's drum in the analysis, if applicable; and (ii) rings as strengthening measure, whose number, position (dome or drum) and material (capacity) are user-defined. The goal is to make the tool easily and freely available at the disposal of students, researchers, and structural engineers.

Masonry structures are highly vulnerable to climate change effects. In particular, over the last few decades, the effects of global warming have caused wetter winters and drier summers. Such phenomenon has produced variations in soil saturation that, in the long term, may trigger consolidation-induced differential settlements. Therefore, the experimental replication of settlement actions is essential for developing appropriate numerical tools and understanding their consequences on masonry structures. This paper describes the installation of a 1.5 × 1m2 settlement table at the University of Minho. Practical issues and first tests on masonry shear walls are also discussed.

•A numerical approach to analyze crack propagation phenomena is proposed.•Moving mesh methodology based on ALE strategy is implemented to predict crack growth.•The model avoids numerical complexities typically observed in classical FE approaches.•Numerical comparisons with existing formulations are developed for the validation. A numerical model based on moving mesh strategy is proposed to simulate the evolution of internal material discontinuities in a continuum medium. The approach combines concepts arising from structural mechanics and moving mesh methodology, which are implemented in a unified framework to predict crack growth on the basis of Fracture Mechanics variables. In particular, moving computational nodes are modified starting from a fixed referential coordinate system on the basis of a crack growth criterion to predict directionality and displacement of the tip front. The use of rezoning mesh methods coupled with a proper advancing crack growth scheme ensures the consistency of mesh motion with small distortions and an unaltered mesh typology. In addition, the moving grid is modified from the initial configuration in such a way that the recourse to re-meshing procedures is strongly reduced. The numerical formulation and its computational implementation show how the proposed approach can be easily embedded in classical finite element software. Finally, numerical examples in the presence of internal material discontinuities and comparisons with existing data obtained by advanced numerical approaches and experimental data are proposed to check the validity of the formulation.

A two-step strategy for the mechanical analysis of unreinforced masonry (URM) structures, either subjected to in-and out-of-plane loading, is presented. At a first step, a semi-automatic digital tool allows the parametric modeling of the structure that, together with an Upper bound limit analysis tool and a heuristic optimization solver, enables tracking the most prone failure mechanism. At a second step, a coupled concurrent FE model with micro-and macro-scales is assumed. A micro-modeling description of the masonry is allocated to regions within the failure mechanism found in the former step. In converse, the other domain regions are modeled via a macro-approach, whose constitutive response is elastic and orthotropic and formulated through closed-form homogenized-based solutions. The application of the framework is based on non-linear static (pushover) analysis and conducted on three benchmarks: (i) an in-plane loaded URM shear wall; (ii) a U-shaped URM structure; and (iii) a URM church. Results are given in terms of load capacity curves, total displacement fields, and computational running time; and compared against those found with a FE microscopic model and with a limit analysis tool. Lastly, conclusions on the potential of the framework and future research streams are addressed.

Predicting the lateral load-carrying capacity of dry-joint unreinforced masonry (URM) walls is often challenging due to the complex interactions between the governing parameters (i.e. geometrical and mechanical properties). The capacity and behavior of dry-joint URM walls depend on boundary conditions, size and location of the openings, bond pattern, vertical load, and aspect ratio, among other factors. In this context, the present research investigates the effect of bond pattern, aspect ratio, vertical load, and boundary condition on the in-plane (IP) behavior and capacity. Two computational methods, the discrete element method (DEM) and micro limit analysis (micro LA), are employed. Through a comprehensive parametric assessment, the result indicates a good agreement between the two approaches. The computational investigations underline the direct relationship of the IP capacity of walls with respect to aspect ratio and applied vertical pressure. Furthermore, fixed-no rotation boundary condition is associated with the increased IP capacity. Finally, a simple analytical equation is proposed to predict the lateral capacity of dry-joint URM walls.

The present work aims to expand the knowledge of the behaviour of masonry corners, which are capital to obtain an integral seismic response in masonry buildings. In particular, the influence of the seismic load orientation (from pi /4 to pi /2) is investigated experimentally, numerically and analytically. Both units and interfaces have been subjected to a material characterisation process, following which pseudo-static 1:4 scaled experiments on a tilting table have been conducted on a symmetric dry-joint masonry corner. The experimental results have also been simulated using a discrete element model. Finally, a new analytical limit analysis model has been devel-oped, which considers both experimental and numerical observations and accounts for rocking-sliding and flexural mechanisms. In general, a good agreement is found between the three approaches, both in terms of collapse mechanism and load multiplier.

Being able to provide outstanding performances under out-of-plane loading, sandwich structures offer great flexibility for the design of lightweight structural systems. However, they can be affected by macroscopic and microscopic damages, which may trigger catastrophic failure modes. As a consequence, a detailed understanding of the propagation of macro-cracks in the core as well as of delamination phenomena at face-to-core interfaces are aspects of great computational interest. Moreover, linking sophisticated numerical models with the measurement of the mechanical properties of materials is fundamental in view of actual engineering applications. The elastic and fracture characterization of the core is particularly relevant because its cracking strongly reduces the capacity of the sandwich structures to carry out loads. To this end, PVC foams typically used as inner core in structural application are investigated over a range of foam densities. Firstly, the elastic properties of foams under compressive uni-axial loading are measured using the full-field methodology. Subsequently, Asymmetric Semi-Circular Bend (ASCB) specimens are tested varying the position of supports to generate all range of mixed fracture modes. Finally, some of the mostly recognized fracture criterions have been considered, and their capability to compute the crack propagation angles in PVC foams have been evaluated. The parameters experimentally determined have been used to test the accuracy of the response provided by a numerical model developed by the authors.

Earthquakes are among the most destructive natural disasters and have resulted in a massive number of fatalities and economic losses all over the world. Simulated ground motion records are valuable, particularly for regions lacking seismic stations or with a limited history of large-magnitude earthquakes. Notably, a significant percentage of monumental masonry buildings are located in regions with limited access to real records; hence, simulated records play a paramount role in their seismic protection. However, few studies have investigated the structural response of heritage buildings via response history analyses to assess the performance of simulated earthquakes against real ones. To accomplish this, this study simulates the recorded time-series of the 9th of July 1998 Faial earthquake in the Azores (Mw = 6.2) at four available stations, using two different simulation approaches, that is, a source-based stochastic finite-fault method and a site-based broadband stochastic method. First, two masonry facades with sidewalls characterized by different slenderness levels are adopted to conduct this research. Moreover, the proposed approach is also applied to an existing monumental structure, that is, São Francisco Church, located at Horta, which was affected by damage during the Faial earthquake. Results demonstrate that both simulation approaches provide similar results in terms of structural response prediction. The proposed framework also demonstrates that a small mismatch in terms of predicted damage patterns can result in a significant relative error in terms of displacement predictions.

A novel numerical strategy to predict dynamic crack propagation phenomena in 2D continuum media is proposed. The numerical method is able to simulate the behavior of materials and structures affected by dynamic crack growth mechanisms. In particular, an efficient computational procedure based on the combination of Fracture Mechanics concepts and Arbitrary Lagrangian and Eulerian approach (ALE) has been developed. This represents a generalization of previous authors' works in a dynamic framework with the purpose to propose a unified approach to predict crack propagation using dynamic or static fracture mechanics and a moving mesh methodology. The crack speed is explicitly evaluated at each time step by using a proper crack tip speed criterion, which can be expressed as function of energy release rate or stress intensity factor. In order to validate the formulation, experimental and numerical results available from the literature are considered. In addition, a parametric study to verify the prediction of proposed modeling in terms of mesh dependence phenomena, computational efficiency and numerical complexity is developed. (C) 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo.

Field earthquake reconnaissance has revealed that masonry corner failure is one of the most common failure mechanisms. In literature, few studies have focused on the experimental investigation of such a mechanism, and they were usually performed considering the seismic action passing from the corner bisector. The present study conducts an experimental campaign on masonry corners and investigates how the orientation of the seismic action affects both the seismic capacity and the collapse mechanism. The experimental campaign involves two masonry corner configurations with different wall aspect ratios. Both configurations are made of a single-leaf dry-joint specimen, built with calcium silicate blocks. Results demonstrate how the orientation of the pseudo-static load simulated by means of a tilting table affects the structural capacity.

Sandwich structures are widely used for the design and fabrication of lightweight structural systems, due to their capability to exhibit excellent structural and thermal performances at low material usage. Understanding the phenomena of propagation of macro-cracks in the core and delamination at the face-to-core interface are aspects of great computational interest. Linking sophisticated models with the actual characterisation of their me-chanical properties is essential in view of real engineering applications. The elastic and fracture characterisation of the materials composing the core is particularly relevant because its cracking affects the capacity of the sandwich structures to carry out transverse loads. In this work, PVC foams typically used as the inner core in structural applications are investigated over a range of foam densities. Firstly, the elastic properties of foams under compressive uniaxial loading are measured using a full-field methodology. Subsequently, Semi-Circular specimens are tested in bending varying the position of supports to generate all range of mixed fracture modes. Suitable fracture criteria are also considered in order to assess their capability to evaluate fracture pa-rameters in PVC foams. Finally, the parameters experimentally determined have been used to validate the response provided by a numerical model developed by the authors.

While the influence of the component strength on the structural behaviour of Historic Masonry Structures (HMS) is relatively well studied, few studies have investigated masonry textures. Such a research gap is due to the actual difficulty of finding parameters that correlate masonry patterns and structural performances. This paper presents a comprehensive review of the existing geometric measures for irregular masonry patterns, highlighting the gaps and possible future trends. Special attention is paid to the Non-destructive Tests (NDT) for surveying masonry textures and algorithms to generate block-based numerical models artificially. Finally, a numerical investigation underlines how masonry textures generated considering quality indexes present more consistent results.

This study aims to improve our current understanding of the seismic assessment of load-bearing unreinforced masonry (URM) systems by proposing a probabilistic computational modeling framework using the discrete element method (DEM). The main objective is to predict the structural behavior and capacity of URM walls with openings subjected to lateral loading, considering uncertainties in material properties. The proposed modeling strategy represents masonry as an assembly of rigid blocks interacting along their boundaries by adopting the point-contact hypothesis. Fracture energy-based softening contact models are implemented into a commercial discrete element code (3DEC) to better simulate both the pre- and post-peak behavior of masonry. The results highlight the influence of material properties on the force capacity, displacement capacity (drift limits), and collapse mechanisms of walls with openings. Based on the applied non-spatial probabilistic analyses, the most commonly observed failure mechanisms are further assessed using a simplified macro-block formulation. As a result, practical, yet necessary, inferences are made, providing valuable contributions. Furthermore, the validated discontinuum analysis framework is demonstrated as an accurate structural analysis strategy and a useful approach to simulating the potential collapse mechanism of load-bearing URM structures. •A probabilistic computational modeling framework is adopted to assess URM walls with openings.•Uncertainty in material properties is taken into consideration in the computational models.•The most and least commonly observed failure mechanisms and their force-displacement capacities are discussed.•The detrimental influence of weak-pier and strong-spandrel systems is highlighted.•A practical macro-block analysis is presented, relying on the pre-defined crack patterns obtained from advanced solutions.

This paper proposes a general equation to assess the crack inclination upper threshold when non-periodic textures characterise masonry walls. The proposed formulation introduces the computation of the frictional resistance at the macro-block interface by evaluating two masonry quality indexes, i.e., vertical and horizontal lines of trace. The proposed equation is adopted in conjunction with a macro-block limit analysis formulation in which the failure mechanism is parametrised and formulated according to the upper bound limit analysis theorem, coupled with a heuristic solver that is able to minimise the load multiplier and identify the geometry of the associated macro-block. The proposed analytical model is verified in a number of case studies by comparing advanced DEM simulations and numerical results arising from the literature.

A systematic literature review on numerical strategies suitable to simulate defects and discontinuities in layered and sandwich structures is presented here. Particular care is given to studies whose scope concerns the so-called Moving Mesh (MM) or Isogeometric Analysis (IGA) methods. A general overview of the peculiarities of each approach is also provided. A total of fifteen and twenty-six journal/conference articles were summarised and categorised for MM and IGA methods, respectively. Based on the available literature, it can be stated that MM approaches generally allow a lower computational burden due to the reduced number of re-meshing steps required when compared to standard finite element approaches. Conversely, IGA approaches bring strong advantages in the geometric description of curved shell structures and, due to a non-uniform rational b-spline interpolation function, ensure higher numerical accuracy in stress analysis problems.

This research investigates the texture influence of masonry walls' lateral capacity by comparing analytical predictions performed via macro and micro limit analysis. In particular, the effect of regular and quasi-periodic bond types, namely Running, Flemish, and English, is investigated. A full factorial dataset involving 81 combinations is generated by varying geometrical (panel and block aspect ratio, bond type) and mechanical (friction coefficient) parameters. Analysis of variance (ANOVA) approach is used to investigate one-way and two-way factor interactions for each parameter in order to assess how it affects the horizontal load multiplier. Macro and micro limit analysis predictions are compared, and the differences in terms of mass-proportional horizontal load multiplier and failure mechanism are critically discussed. Macro and micro limit analysis provide close results, demonstrating the reliability of such approaches. Furthermore, results underline how the panel and block aspect ratio had the most significant effect on both the mean values and scatter of results, while no significant effect could be attributed to the bond types.

Predicting the seismic behavior of unreinforced masonry (URM) structural systems is a complex task, given various inherent sources of uncertainty associated with material properties, geometry, and boundary conditions. As the selection of computational strategies is a trade-off between prediction accuracy and computational cost, it is often challenging to find a consensus. To this end, this study presents three computational modeling strategies that can be used in the seismic analysis of URM structures. The first two approaches utilize the discrete element method (DEM) and are based on pre-defined macro-block mechanisms, whereas the third approach makes use of the computational thrust line analysis (CTLA). Such methods provide accurate predictions on the in-plane lateral load-carrying capacity of URM pier-spandrel structures with a reasonable computational cost and fewer input parameters, making them efficient compared to detailed numerical models. The results are found to be in good agreement with the experimental data on two full-scale pier-spandrel systems with either timber lintel or shallow arch above a central opening. This study also provides a detailed comparison of the applied methods and suggests multi-level use of proposed modeling strategies for better informed decision-making, starting from the most simplified method (CTLA) towards the advanced solutions as more information is collected.

A numerical model to predict crack propagation phenomena in sandwich structures is proposed. The model incorporates shear deformable beams to simulate high performance external skins and a 2D elastic domain to model the internal core. Crack propagation is predicted in both core and external skin-to-core interfaces by means of a numerical strategy based on an Arbitrary Lagrangian-Eulerian (ALE) formulation. Debonding phenomena are simulated by weak based connections, in which moving interfacial elements with damage constitutive laws are able to reproduce the crack evolution. Crack growth in the core is analyzed through a moving mesh approach, where a proper fracture criterion and mesh refitting procedure are introduced to predict crack tip front direction and displacement. The moving mesh technique, combined with a multilayer formulation, ensures a significant reduction of the computational costs. The accuracy of the proposed approach is verified through comparisons with experimental and numerical results. Simulations in a dynamic framework are developed to identify the influence of inertial effects on debonding phenomena arising when different core typologies are employed. Crack propagation in the core of sandwich structures is also analyzed on the basis of fracture parameters experimentally determined on commercially available foams.

Steel Reinforced Grout (SRG) materials are generating considerable interest as strengthening system of reinforced concrete (RC) structures. They are finding increasing use in several civil engineering applications mainly due to the advantages they offer over traditional material such as high strength to weight ratio, ease of application, durability and low price. This paper describes the results of an experimental investigation carried out on SRG shear strengthened RC beams and gives evidence of the Digital Image Correlation (DIC) effectiveness as a measurement system. The tests performed had two main objectives: (i) assess the effectiveness of continuous and discontinuous U-wrapped jackets comprising a different number of layers and strips; (ii) assess the shear crack distribution during the tests by means of the DIC measurements. The results confirmed that reinforcing RC beams with SRG jackets can increase the load-bearing capacity; when the beam was reinforced with a continuous two-layered SRG strip, an increase of 84% was observed (compared to the unreinforced beam). The Linear Variable Differential Transformers (LVDT) measurements validated the results obtained by means of the DIC.

In the last decade, sandwich structures spread a great interest in civil engineering applications. However, despite their excellent mechanical performance, they can be affected by macroscopic and microscopic damages, which may trigger catastrophic failure modes. Detailed understanding of the physical and mechanical properties is needed in order to allow refined numerical models to describe structural behaviour under intensive loading conditions, accurately. The elastic and fracture characterisation of the core material is particularly relevant because cracking phenomenon strongly reduces the capacity of the sandwich structures to carry out loads. PVC foams, typically used as the inner core in a structural application, are investigated over a range of foam densities. PVC foams H100, H130, and H200, produced by DIAB. The elastic properties of foams under compressive uni-axial loading are measured using the full-field methodology.

This paper proposes a methodology to define code-based indicators of the seismic behaviour of existing masonry structures. Given the geometrical information about the structure under investigation, the proposed method performs real-time structural checks according to the EN 1998–1 – “General rules, seismic actions and rules for buildings”. Then, modal analysis is performed to assess the structure's dynamic behaviour under investigation and to assist the user in defining retrofit measures. In this study, 103 masonry buildings located in Zagreb are analysed, accounting for the cross-sectional area of load-bearing walls, geometric requirements for shear walls, regularity of plan configuration and its symmetry, torsional effects induced by the distance of the centres of mass and stiffnesses, and modal analysis. The workflow is implemented into the environment offered by Rhino3D and Grasshopper, which allows for the parametric handle of a large set of information through object-oriented scripts, and it can be valuable for both pre-earthquake and post-earthquake assessments of masonry buildings.

A new methodology to predict dynamic crack propagation under generalized loading conditions is proposed. The numerical modeling combines structural mechanics and moving mesh method with the purpose to predict geometry variation produced by the evolution of existing material discontinuities. In particular, moving mesh method is implemented to enforce crack tip displacements by using an explicit crack criterion based on referential and moving configurations. In this framework, the use of mesh regularization method based on proper rezoning equations is able to reduce the use of remeshing attempts, typically required by standard crack propagation procedures. Dynamic crack growth is predicted by a rate dependent criterion, expressed in terms of crack angle and driven forces based on energy release rate definition. The model is quite suitable to predict the evolution of material discontinuities, typically observed in composite structures. Numerical implementation, developed in the framework of a finite element formulation and details on the solving procedure, are presented. The proposed modeling is validated by several comparisons with experimental and numerical data, which show accuracy and robustness of the numerical approach. Moreover, sensitivity analyses in terms of mesh dependence and time required for the solving procedure are also developed.

Building design codes recommend using nonlinear dynamic analysis for an appropriate assessment of the seismic response of several types of structures. To perform nonlinear dynamic analysis, the recorded ground motion time histories of past events with a certain seismic intensity level compatible with the regional seismological characteristic are usually scarce. Therefore, alternative selection and scaling methods on the previously recorded ground motion data set are commonly employed to overcome this issue. However, the type of method and also the random characteristics of earthquake ground motion data induce variability in the estimation of structural response. In this paper, the effect of code-based ground motion selection approaches is investigated in predicting the seismic demand of masonry structures. The dynamic behaviour of the masonry prototype is simulated through a 3D numerical model. The material non-linearities are taken into account by adopting a proper constitute law. The data set of PEER is used as the pool for selection and scaling based on various codes, including American standard, Eurocode, Turkish seismic code, Iranian seismic code, and New Zealand standard. Results showed that alternative code-based selection approaches reach various seismic demand levels. Keywords: Ground motion records, PEER data set, Scaling, Code-based selection, Masonry structures, Incremental dynamic analysis

This work aims at proposing a novel procedure for the seismic assessment of historic masonry structures which is computationally efficient and does not rely on destructive material tests. Digital datasets describing the geometric configuration of historic masonry structures are employed to automatically generate a non-linear Finite Element (FE) model and investigate on possible collapse modes. A configuration of failure surfaces is therefore detected through the Control Surface Method (CSM), which is here proposed for the first time. In a following step of the analysis, structural macroblocks are identified, whereas an upper bound limit analysis approach is employed to estimate the structural capacity of the structure. Genetic Algorithms are also employed to detect the actual failure mode for the structure. The procedure is implemented into a visual coding environment, which allows one to parametrically explore all possible failure surfaces and immediately visualize the effects of the user assumptions. This is particularly suited to support a decisions-making process which strongly relay on engineering judgement. The procedure is validated by the analysis of two benchmark cases, whose results are presented and discussed.

A new methodology to predict interfacial debonding phenomena in fibre-reinforced polymer (FRP) concrete beams in the serviceability load condition is proposed. The numerical model, formulated in a bi-dimensional context, incorporates moving mesh modelling of cohesive interfaces in order to simulate crack initiation and propagation between concrete and FRP strengthening. Interface elements are used to predict debonding mechanisms. The concrete beams, as well as the FRP strengthening, follow a one-dimensional model based on Timoshenko beam kinematics theory, whereas the adhesive layer is simulated by using a 2D plane stress formulation. The implementation, which is developed in the framework of a finite element (FE) formulation, as well as the solution scheme and a numerical case study are presented.

New technologies are changing the way engineers work within the construction sector. Newly developed software solutions have provided effective methods to explore the design space at the interface between Structural Engineering and Architecture, allowing more efficient design strategies. These technologies are based on the integration of parametric generation and visualisation of geometries with powerful numerical solvers, employing user-customised routines. While the construction industry is rapidly moving the design of new construction towards a fully digitalised process, the assessment and the analysis of existing structures with such tools are still largely unexplored. In this context, a visual script for the structural assessment of out-of-plane mechanisms in historic masonry structures subject to seismic loading has recently been proposed by the authors. This relies on two successive steps of analysis, which are integrated into a digital work-flow. Datasets describing the geometric configuration of masonry structures are employed to automatically generate a non-linear Finite Element (FE) model and investigate possible collapse modes. A preliminary global analysis is performed using the commercial software ABAQUS CAE. This, in combination with the Control Surface Method (CSM), allows identifying the most likely failure mechanisms which are described by the geometry of the macro-blocks. The parametric modelling of the macro-blocks geometry allows exploring the domain of possible solutions using the upper bound method of limit analysis. A Genetic Algorithms (GA) solver is used to refine the geometry of the macro-blocks and search the minimum of the upper-bound load multipliers, which guarantees equilibrium. The script is implemented in the visual programming environment offered by Rhino3D+Grasshopper. In this paper, a set of parametric analyses considering various input variables such as friction coefficient and opening incidence are performed to verify both the sensitivity and the accuracy of the proposed method.

This study investigates the effect of spatially varying material properties on the in-plane seismic behaviour and capacity of an unreinforced pier-spandrel masonry system. The discontinuous nature of masonry is represented via a system of rigid blocks that can mechanically interact with each other along their boundaries. In the discontinuous modelling strategy, denoted as discrete rigid block analysis (D-RBA), deformations are lumped at the joints, and masonry units are replicated using two rigid blocks with a potential crack plane using the discrete element method (DEM). The obtained collapse mechanisms are automatically classified into two main categories via an algorithm processing the results of D-RBA. The adopted methodology offers a robust and time-efficient categorization of different collapse modes obtained from the computational model, which is required for better understanding the possible mechanisms developing in pier-spandrel structures and their occurrence rate. Accordingly, the most recurrent failure mechanisms are further investigated via upper- and lower-bound theorems of limit equilibrium analysis (LEA) by adopting an ad hoc coded optimization algorithm to ensure the solution's uniqueness. The results show that the DEM-based modelling approach provides a comprehensive understanding of the structural behaviour and capacity of pier-spandrel systems subjected to in-plane lateral loads. Further, the proposed probabilistic assessment workflow offers a broader perspective than deterministic analysis.

The purpose of this study is to explore Artificial Neural Networks (ANNs) to predict the compressive and tensile strengths of natural fibre-reinforced Compressed Earth Blocks (CEBs). To this end, a database was created by collecting data from the available literature. Data relating to 332 specimens (Database 1) were used for the prediction of the compressive strength (ANN1), and, due to the lack of some information, those relating to 130 specimens (Database 2) were used for the prediction of the tensile strength (ANN2). The developed tools showed high accuracy, i.e., correlation coefficients (R-value) equal to 0.97 for ANN1 and 0.91 for ANN2. Such promising results prompt their applicability for the design and orientation of experimental campaigns and support numerical investigations.

Featured Application Rapid seismic assessment of historic masonry structures. This paper presents a user-friendly, CAD-interfaced methodology for the rapid seismic assessment of historic masonry structures. The proposed multi-level procedure consists of a two-step analysis that combines upper bound limit analysis with non-linear dynamic (rocking) analysis to solve for seismic collapse in a computationally-efficient manner. In the first step, the failure mechanisms are defined by means of parameterization of the failure surfaces. Hence, the upper bound limit theorem of the limit analysis, coupled with a heuristic solver, is subsequently adopted to search for the load multiplier's minimum value and the macro-block geometry. In the second step, the kinematic constants defining the rocking equation of motion are automatically computed for the refined macro-block model, which can be solved for representative time-histories. The proposed methodology has been entirely integrated in the user-friendly visual programming environment offered by Rhinoceros3D + Grasshopper, allowing it to be used by students, researchers and practicing structural engineers. Unlike time-consuming advanced methods of analysis, the proposed method allows users to perform a seismic assessment of masonry buildings in a rapid and computationally-efficient manner. Such an approach is particularly useful for territorial scale vulnerability analysis (e.g., for risk assessment and mitigation historic city centres) or as post-seismic event response (when the safety and stability of a large number of buildings need to be assessed with limited resources). The capabilities of the tool are demonstrated by comparing its predictions with those arising from the literature as well as from code-based assessment methods for three case studies.

Historic masonry buildings are characterised by uniqueness, which is intrinsically present in their building techniques, morphological features, architectural decorations, artworks, etc. From the modelling point of view, the degree of detail reached on transforming discrete digital representations of historic buildings, e.g., point clouds, into 3D objects and elements strongly depends on the final purpose of the project. For instance, structural engineers involved in the conservation process of built heritage aim to represent the structural system rigorously, neglecting architectural decorations and other details. Following this principle, the software industry is focusing on the definition of a parametric modelling approach, which allows performing the transition from half-raw survey data (point clouds) to geometrical entities in nearly no time. In this paper, a novel parametric Scan-to-FEM approach suitable for architectural heritage is presented. The proposed strategy uses the Generative Programming paradigm implementing a modelling framework into a visual programming environment. Such an approach starts from the 3D survey of the case-study structure and culminates with the definition of a detailed finite element model that can be exploited to predict future scenarios. This approach is appropriate for architectural heritage characterised by symmetries, repetition of modules and architectural orders, making the Scan-to-FEM transition fast and efficient. A Portuguese monument is adopted as a pilot case to validate the proposed procedure. In order to obtain a proper digital twin of this structure, the generated parametric model is imported into an FE environment and then calibrated via an inverse dynamic problem, using as reference metrics the modal properties identified from field acceleration data recorded before and after a retrofitting intervention. After assessing the effectiveness of the strengthening measures, the digital twin ability of reproducing past and future damage scenarios of the church is validated through nonlinear static analyses.

Undoubtedly, heritage buildings serve as essential embodiments of the cultural richness and diversity of the world's states, and their conservation is of the utmost importance. Specifically, the protection of the structural integrity of these buildings is highly relevant not only because of the buildings themselves but also because they often contain precious artworks, such as sculptures, paintings, and frescoes. When a disaster causes damage to heritage buildings, these artworks will likely be damaged, resulting in the loss of historical and artistic materials and an intangible loss of memory and identity for people. To preserve heritage buildings, state-of-the-art recommendations inspired by the Venice Charter of 1964 suggest real-time monitoring of the progressive damage of existing structures, avoiding massive interventions, and providing immediate action in the case of a disaster. The most up-to-date digital information and analysis technologies, such as digital twins, can be employed to fulfil this approach. The implementation of the digital twin paradigm can be crucial in developing a preventive approach for built cultural heritage conservation, considering its key features of continuous data exchange with the physical system and predictive analysis. This paper presents a comprehensive overview of the digital twin concept in the architecture, engineering, construction, and operation (AECO) domain. It also critically discusses some applications within the context of preserving the structural integrity of architectural heritage, with a particular emphasis on masonry structures. Finally, a prototype of the digital twin paradigm for the preservation of heritage buildings' structural integrity is proposed.

The Digital Twin (DT) technology has shown promise in transforming complex engineered systems. However, its adoption in the Architecture, Engineering, Construction, and Operation (AECO) field, particularly for Built Cultural Heritage (BCH) conservation, is still in its early stages. This study presents a systematic literature review of 85 academic publications to evaluate the current state of DT implementation in heritage building conservation and identifies areas for optimising preventive management. In addition, this review explores interpretations of the DT concept in this field, addressing overlaps with Historical/Heritage Building Information Modelling (HBIM), discusses DT functionalities and presents existing frameworks. The findings demonstrate the potential of DT to revolutionise BCH conservation through a holistic approach. However, further focus is needed on features and tools for enhancing performance-based management with targeted strategies and advanced data analysis. Future research should prioritise developing these aspects to fully leverage the potential of the DT paradigm in BCH conservation.

Masonry bond patterns can considerably affect the seismic performance of in-plane walls. Although several numerical and experimental works addressed this topic, few attempts tried to investigate such an issue using analytical formulations. This paper aims to compare macro and micro limit analysis models investigating masonry walls arranged with different bond types, namely Running, Flemish and English. A dataset involving 81 combinations is generated by varying geometrical (panel aspect ratio, block aspect ratio, bond type) and mechanical (friction coefficient) parameters. Finally, one-way and two-way factor interactions are used to evaluate how each parameter affects the horizontal load multiplier and assess matching among the two adopted formulations.