Search

Structural health monitoring is an essential tool for assessing the performance of buildings and infrastructure, especially after critical events or the application of structural interventions. When dealing with architectural heritage structures, both structural health monitoring instrumentation and intervention materials need to be as inconspicuous and unintrusive as possible, both in terms of mechanical compatibility and aesthetics. Therefore, the design of smart sensors based on construction materials used in conservation engineering promises to provide an acceptable integrated structural health monitoring and upgrading solution for historic structures, Postprint (updated version)

his paper presents the results from an experimental campaign to characterise the shear behaviour of the brickwork-backfill interaction in masonry arch bridges. Two representative backfill materials found in real masonry arch bridges (compacted crushed limestone and clay) were sheared against brickwork masonry specimens with two different bond patterns (a soldier course bond and an English bond), This work was funded by the EPSRC project ‘Exploiting the resilience of masonry arch bridge infrastructure: 3D multi-level modelling framework’ (ref. EP/T001348/1)., Postprint (published version)

Masonry structures composed of two distinct material phases (units and mortar) with potentially vastly different elastic properties are characterised by strong orthotropy. The variety of commonly employed bond typologies for masonry walls, featuring unit groups and mortar joints with different orientation with respect to the plane of the wall, result in complex stress and strain interactions between the material phases., Postprint (published version)

This thesis aims to develop a low-cost data acquisition system to record electrical resistance and deformation data in self-sensing smart cement specimens. Subsequently, the developed system must be tested with cyclic load tests, a text file must be generated with the data obtained and said data must be analysed to extract conclusions about the performance of the system and the piezoresistive "smartness" of the materials. The most interesting application of this thesis is to implement the system designed in an intelligent cement for Structural Health Monitoring applications, where a structure can be continuously monitored to detect deformations and possible failures before they happen. For this reason, the research on this thesis’s state of the art has focused on the current applications of smart cement, current SHM systems and research about low-cost solutions. To achieve the thesis goals, fluent communication has been established between the thesis director and the author, both by exchanging emails and face-to-face meetings. In addition, face-to-face sessions have been held in the Resistance of Materials laboratory, such as preparing the test specimens and testing the data acquisition system at different points in the thesis. The results show that the developed system can record electrical resistance and deformation data and generate text files for its processing. The analysis of the obtained data also illustrates the linear relationship between the fractional change in the electrical resistance and the deformation, allowing in this way to characterize the specimens with their gauge factor and thus determine their "smartness”. To sum up, it can be established that this thesis manages to develop a low-cost system for the acquisition of reliable and replicable data and, due to its linear relationship, the cement can be considered "self-sensing" since the application of a load is translated into a change into the electrical resistance, eliminating in this way the nee

This thesis investigates interpolation techniques for modeling the velocity field in the Lid-Driven Cavity with Stokes flow, inspired by the potential utility of these techniques in the aeronautical field to reduce computational costs. The aim is to compare and evaluate interpolation approaches for accurately predicting the velocity distribution during horizontal and vertical deformations. The study begins with one-parameter interpolation using right singular vectors. Singular value decomposition (SVD) is employed to decompose the data and approximate the velocity distribution for values of the horizontal elongation of the cavity which fall within the range of values considered during the study. This interpolation demonstrates to allow extrapolation within a limited scope. Building upon the insights gained, the research progresses to two-parameter interpolation using right singular vectors, considering both horizontal and vertical deformations. However, as deformations increase, accuracy significantly diminishes, raising concerns about result reliability. Interpolation using right singular vectors lacks compliance with the fundamental Navier-Stokes equations, so this thesis explores alternative approaches. Specifically, Model Order Reduction (MOR) is introduced as a means to reduce computational costs. It is important to note that MOR for the Navier-Stokes equations is not performed in this study. Instead, the focus is on investigating interpolation techniques that generate matrices of basis vectors, which play a key role in MOR. These matrices, if used in future MOR investigations, can facilitate estimating the resultant velocity field by interpolating parameter values. The interpolation technique using principal angles enables computation of the subspace matrix containing velocity field results, demonstrating sufficient accuracy through error analysis. However, the method has limitations in extrapolating beyond the studied deformation range and studying interpolat

The study focuses on the case of the Church Santa Maria de Barberà de la Conca, a three-nave baroque masonry Church, built during 18th century, located in Catalonia. Because of the significant damage that the Church is suffering, and the fact that the ground movement and the opening of cracks are continuing, it is necessary to quickly implement stabilization or strengthening solutions because the Church is threatened with collapse. The severely damaged Rose Chapel was demolished recently, and the Church and its surroundings are closed. The study also describes the current monitoring of progressively growing soil cracks. Existing structure calculation was done based on graphic static analysis, a simple, fast, convenient, and straightforward method to determine the Church's stability in the initial state versus the stability in the currently damaged stage. The second goal of the graphic static analysis was to determine the internal forces and base reactions as input for the strengthening solution calculation. By considering possible alternative solutions for the strengthening of the Church, it was established that it is necessary to strengthen the Church at the foundation level. A chosen solution with sufficient capacity to resist the large tensile forces that the movements of the soil may cause can be provided in the form of a prestressed concrete grillage rigidly connected to the existing masonry walls. The solution is designed as a reversible one, in the way that the transverse prestressing is without grouting. Additionally, the maintenance plan and monitoring of the prestressed structure is foreseen to monitor the level of force achieved with the strengthening solution. Finally, repair and strengthening operations designed for the rest of the structure (walls, pillars, arches, and vaults) are briefly described to stabilize the Church entirely and restore it, enabling its public use again.

This thesis presents the development of a research methodology oriented to the analysis of an aircraft structure in terms of operational reliability and maintainability requirements regarding its airworthiness. The study has been focused on modern commercial aircraft models, carrying out a market research and model selection according to different criteria. The study then develops a practical implementation consisting of the design approach of the aircraft airframe and main structural components for its subsequent numerical analysis and simulation. The numerical simulations will be computed by application of the Finite Elements Method on the main structural systems of the aircraft and establishment of boundary conditions. These simulations will allow the development of a computational study on linear, non-linear, and transient simulations of static loads, buckling, modal analysis, temperature, fatigue and thermal stress of individual structures and full assembly in different conditions. Finally, these results will be assessed and exported to a Matlab code which will compute an algorithmic methodology in order to approach the operational reliability and safety of the aircraft in the studied conditions. The thesis will conclude with a review of airworthiness regulations a proposal of research paths and further development of the methodology implemented.

This project starts by studying the finite element method for the steady state Navier-Stokes equations, afterwards it is implemented in Matlab and optimized via Vectorization achieving up to 5000x speed-up in some calculations. Then a reduced order model is studied to decrease the computational time of performing different simulations with slight modifications to the input parameters. Finally, the results obtained are compared against an already tested FEM code, Kratos Multiphysics, and against literature, and the performance of the developed solver for the equations is analyzed. It has been observed that the results obtained with the present work’s solver are almost equal to those made by the reference alternatives.

This paper aims to present a systematic framework for material characterisation to assess brickwork masonry arch bridges. An extensive laboratory campaign was carried out to characterise brickwork and backfill material in masonry arch bridges. Initially, the strength and Young’s modulus of bricks and mortar, as well as the internal friction angle and cohesion of the backfill materials (e.g., crushed limestone and puddling clay), were characterised by undertaking small-scale material level tests., This work was funded by the EPSRC project ‘Exploiting the resilience of masonry arch bridge infrastructure: a 3D multi-level modelling framework’ (ref. EP/T001348/1). The financial contribution is very much appreciated. Moreover, the authors would like to gratefully acknowledge the valuable support received from the technicians in the George Earle Lab at the University of Leeds; in particular, the authors are thankful to: Mr. Ian Day, Mr. Marvin Wilman, Mr. Robert Clarke, and Mr. Patrick Gregory., Peer Reviewed, Postprint (published version)

Through simulation-based study, this thesis explores the possible benefits of using Carbon Fibre Reinforced Polymer (CFRP) materials for A320neo fan blades rather than Ti6Al4V. The study seeks to evaluate the viability and performance advantages of CFRP composites with a focus on electrical and mechanical qualities. At first SolidWorks is used to generate a 3D solid model of the fan blade as a realistic representation for the simulations. After that, I compared the electrical conductivity, dielectric constant and mechanical properties, such as, Young’s Modulus of CFRP samples to the typical Ti6Al4V alloy, simulations are run using MATLAB. In order to get knowledge on the state of CFRP materials today, their manufacturing procedures, and their electrical and mechanical properties, the study methodology entails a thorough literature review. In order to faithfully reproduce the behaviour of CFRP under the operational circumstances encountered by A320neo fan blades, the simulation framework is created in MATLAB using well-established models and techniques. In order to verify the correctness and dependability of the simulation approach, the simulated outcomes are compared and analysed against the available data and industry standards. The results of this study help to clarify how CFRP’s electrical and mechanical characteristics relate to A320neo fan blades. The simulation results provide important light on the possible advantages of CFRP materials, such as weight reduction, which is essential in aviation. The models also make it possible to investigate electrical conductivity, which helps determine if CFRP is suitable for electrical grounding and lightning strike protection. In order to fully represent the component in the simulations, the study also entails building a realistic 3D solid model of the fan blade using SolidWorks. This makes it easier to evaluate CFRP materials mechanical behaviour more precisely, facilitating a more thorough evaluation of their appropriate

Due to the complex interaction of its constituent materials, arising from their brittleness and staggered geometric arrangement, masonry as a composite material is often characterised by pronounced orthotropy, both in elasticity and strength [20]. This orthotropy is particularly important in the study of earthquake induced damage and collapse mechanisms of large masonry structural elements [23]. Accurate prediction of the force capacity of masonry elements, therefore, relies not only on the careful mechanical character- isation of its comprising materials, but also on modelling their interaction at the material scale [32]. Finite element (FE) analysis of masonry structures can assume different levels of detail for the representation of the mechanical features and potential failure modes of the material. For example, in a macro-modelling approach the material may be treated as an isotropic [7] or orthotropic [26] continuum. The large number of material parameters in need of characterisation for the execution of these simulations has led to the development of experimental frameworks [12], empirical approaches [11] and numerically-driven calibration methods [16] for determining these parameters. While both approaches have been successfully used for nonlinear anal- ysis [8,21,28], it is the latter that provides a truer representation of the mechanical properties of masonry. Continuum modelling can be very attractive due to the geometrical simplicity of the resulting models and the reduced computational costs, especially for modelling large structures. However, orthotropic models must still rely on complex experiments, well-founded assumptions or ancillary computations for actually determining the orthotropic properties of the continuum. Stemming from the inherent attractiveness of continuum modelling and the need for deriving macroscopic orthotropy from ma- terials that are themselves often isotropic, constitutive approaches have been developed for taking into account t, Peer Reviewed, Postprint (published version)

The mechanical properties of masonry, both in the linear elastic range and after the onset of damage, are dependent on the geometric and mechanical properties of its constituent materials: the units and the mortar. Finite element micromodelling, while capable of providing accurate and comprehensive results, is associated with high computational costs and modelling effort. On the other hand, micromechanical homogenisation of the masonry composite provides an attractive alternative to detailed micromodelling, in which the stress and strain interaction between the material phases can be modelled without excessive computational cost and in which interpretation of the damage state of the phases is more straightforward. However, nonlinear micromechanical homogenisation of masonry elements through varied numerical and analytical approaches remains a subject of intense study. In this paper, an inclusion-based homogenisation scheme for masonry structures is proposed for plane stress conditions. The scheme is combined with constitutive laws for damage in the constituent materials of the masonry composite and implemented in finite element models. The proposed modelling approach is validated in terms of its capacity to predict the elastic properties against experimental results and a finite element benchmark. Finally, finite element analyses of walls subjected to in-plane shear under varying levels of vertical stress are performed and favourably compared with experimental results in terms of predicted capacity and obtained failure mode. The low computational cost of the proposed model makes it suitable for future application in digital twinning operations., Peer Reviewed, Postprint (published version)

A homogenisation scheme based on inclusion modelling is coupled with constitutive laws for damage and implemented in a finite element model for the simulation of concrete and reinforcement bar damage in reinforced concrete structures. The scheme is employed for simulating the behaviour of evenly distributed reinforcement and adapted for the simulation of zones with concentrated reinforcement in structural members. The model is validated against experimental tests from the literature carried out on reinforced concrete members subjected to bending and direct tension. The model captures the main characteristics of the behaviour of and damage in the constituent materials of reinforced concrete without resorting to individual meshing of the embedded bars and with very low computational cost., Peer Reviewed, Postprint (published version)

Masonry structures are characterised by low tensile strength and limited ductility. Excessive static or high-cyclic loading or seismic excitation can lead to large localised strains and cracking. It is therefore essential to monitor the response of masonry structures to external loading, especially in the case of historic buildings and infrastructure. The present work aims at designing novel smart intervention materials for multifunctional application in historic masonry structures as a means of SHM, simultaneously structurally and chemically compatible with the in-situ material. The materials investigated consist of lime mortars mixed with different conductive micro- and nanofillers dispersed in the binder. Smartness stems from the materials’ enhanced piezoresistivity, namely the constitutive relation between strain and electrical resistivity. Through application as a repointing agent in existing structures, these materials can be used as deformation and damage sensors. Electromechanical testing employing cyclic compression was conducted on mortars with different doping levels of three conductive fillers: graphite powder, carbon nanotubes and carbon microfibres. The electromechanical study involved the determination of the piezoresistive gauge factors of the different mixes for determining the optimal doping level for each employed filler. The mortars were evaluated in terms of piezoresistive sensitivity and structural application scalability., This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No.101023384 (S-RePaIR: Smart Restoration with Particle Infused Repointing)., Peer Reviewed, Postprint (author's final draft)

Masonry panels consisting of piers and spandrels in buildings are vulnerable to in-plane actions caused by seismicity and soil subsidence. Tectonic seismicity is a safety hazard for masonry structures, whereas low-magnitude induced seismicity can be detrimental to their durability due to the accumulation of light damage. This is particularly true in the case of unreinforced masonry. Therefore, the development of models for the accurate prediction of both damage initiation and force capacity for masonry elements and structures is necessary. In this study, a method was developed based on analytical modeling for the prediction of the damage initiation mode and capacity of stand-alone masonry piers; the model was then expanded through a modular approach to masonry walls with asymmetric openings. The models account for all potential damage and failure modes for in-plane loaded walls. The stand-alone piers model is applicable to all types of masonry construction. The model for walls with openings can be applied as is to simple buildings but can also be extended to more complex structures with simple modifications. Model results were compared with numerous experimental cases and exhibited very good accuracy., Peer Reviewed, Postprint (author's final draft)

A vital aspect when modelling the mechanical behaviour of existing masonry structures is the accuracy in which the geometry of the real structure is transferred in the numerical model. Commonly, the geometry of masonry is captured with traditional techniques (e.g. visual inspection and manual surveying methods), which are labour intensive and error-prone. Over the last ten years, advances in photogrammetry and image processing have started to change the building industry since it is possible to capture rapidly and remotely digital records of objects and features. Although limited work exists in detecting distinct features from masonry structures, up to now there is no automated procedure leading from image-based recording to their numerical modelling. To address this, an innovative framework, based on image-processing, has been developed that automatically extracts geometrical features from masonry structures (i.e. masonry units, mortar, existing cracks and pathologies, etc.) and generate the geometry for their advanced numerical modelling. The proposed watershed-based algorithm initially deconstructs the features of the segmentation, then reconstructs them in the form of shared vertices and edges, and finally converts them to scalable polylines. The polylines extracted are simplified using a contour generalisation procedure. The geometry of the masonry elements is further modified to facilitate the transition to a numerical modelling environment. The proposed framework is tested by comparing the numerical analysis results of an undamaged and a damaged masonry structures, using models generated through manual and the proposed algorithmic approaches. Although the methodology is demonstrated here for use in discrete element modelling, it can be applied to other computational approaches based on the simplified and detailed micro-modelling approach for evaluating the structural behaviour of masonry structures., This work was partially funded by European Union's Framework Programme for Research and Innovation Horizon 2020, under the H2020-Marie–Skłodowska Curie Actions-COFUND scheme (Grant Agreement ID: 754511), and from the banking foundation Compagnia di San Paolo., Peer Reviewed, Postprint (published version)

This paper aims to quantify the evolution of damage in masonry walls under induced seismicity. A damage index equation, which is a function of the evolution of shear slippage and opening of the mortar joints, as well as of the drift ratio of masonry walls, was proposed herein. Initially, a dataset of experimental tests from in-plane quasi-static and cyclic tests on masonry walls was considered. The experimentally obtained crack patterns were investigated and their correlation with damage propagation was studied. Using a software based on the Distinct Element Method, a numerical model was developed and validated against full-scale experimental tests obtained from the literature. Wall panels representing common typologies of house façades of unreinforced masonry buildings in Northern Europe i.e. near the Groningen gas field in the Netherlands, were numerically investigated. The accumulated damage within the seismic response of the masonry walls was investigated by means of representative harmonic load excitations and an incremental dynamic analysis based on induced seismicity records from Groningen region. The ability of this index to capture different damage situations is demonstrated. The proposed methodology could also be applied to quantify damage and accumulation in masonry during strong earthquakes and aftershocks too., The work presented in this paper is supported by the – Seismic Monitoring, Design and Strengthening For thE GrOningen Region, Project number: RAAK.MKB09.021., Peer Reviewed, Postprint (published version)

The article proposes a methodology for assessing the development of damage in building structures, subjected to differential settlement and uplift, using the analysis of Interferometry Synthetic Aperture Radar (InSAR) data. The proposed methodology is targeted towards general applicability, capable of providing assessment results for measurements over wide geographic areas and for varying structural typologies. The methodology is not limited to ground movement measurements linked to tunnelling, as is the common case. Instead it extends to the monitoring of arbitrary movement in buildings, for example, due to ground consolidation, water table changes or excavation. The methodology is designed for use alongside patrimonial building databases, from which data on individual building geometry and typology are extracted on a region or country scale. Ground movement monitoring data are used for the calculation of the building deformation, expressed in different types of deformation parameters. The combined use of this data with analytical models for settlement damage classification in building structures enables the assessment in patrimonial building structures, at a country scale. The methodology is elaborated and applied on the patrimonial inventory of Belgium for the evaluation of potential settlement and uplift damage on buildings over a period of nearly three decades. The analysis results are compared to on-site observations., The authors would like to acknowledge the funding received by BRAIN.be, BelSPO in support of the GEPATAR research project (“GEotechnical and Patrimonial Archives Toolbox for ARchitectural conservation in Belgium” BR/132/A6/Gepatar)., Peer Reviewed, Postprint (published version)

Three-leaf masonry panels are typically composed of external leaves of irregularly bonded units and a rouble infill. The complexity of the response of these structures to mechanical loading arises from: a) the interaction of the leaves and b) the irregularity of the bond pattern of the outer leaves. This complexity makes analytical and computational modelling of these structures difficult and costly, respectively. This paper proposes a computational approach for the calculation of the mechanical properties of the three- leaf masonry from the properties of its constituent materials and its geometry. Using micro-mechanical anal- ysis approaches applied in composite materials and accounting for the interaction of the leaves through a simple analytical approach, the homogenised elastic stiffness and strength of a representative volume element of three- leaf masonry can be calculated with very low computational cost. The analysis method is validated against experimental results from the literature. It is found that the proposed model provides accurate results for a relatively wide range of case studies. These results are expanded upon through a sensitivity study, highlighting the most important material and geometric parameters influencing the predicted compressive strength of three-leaf masonry walls, This work was funded by the EPSRC project “Exploiting the resilience of masonry arch bridge infrastructure: a 3D multi-level modelling framework” (ref. EP/T001348/1)., Peer Reviewed, Postprint (published version)

The province of Groningen in the Netherlands is experiencing the continuous impact of gas extraction in the form of induced seismicity. Due to the absence of naturally occurring seismicity in the region, the historic building stock of Groningen was constructed without empirical design features typically encountered in naturally seismic regions. Further, gas extraction, in combination with soft topsoil, is responsible for substantial amounts of ground subsidence. This subsidence may compromise the capacity of existing structures to bear seismic loading. Historic masonry structures, particularly those lacking traditional earthquake-resistant features, are vulner- able to seismic loads. Further, their substantial weight, in-plane stiffness, low tensile strength and brittleness renders them vulnerable to settlement-induced damage. Given the cultural significance of architectural heritage, the performance of historic buildings in the Damage Limitation (DL) state is a matter of importance. Additionally, due to the incorporation of both vernacular and monumental architectural heritage buildings in the urban setting, their performance in the Near Collapse (NC) state is as important as that of ordinary building structures. Therefore, methods and techniques for enhancing the behaviour of historic buildings in both States need to be devised and evaluated. This paper focuses on the application and assessment of a retrofitting technique commonly used for damage prevention and repair in unreinforced masonry structures in the Netherlands, namely bed joint reinforced re- pointing. The technique consists in the embedment of stainless-steel bars in continuous bed joints, as well as their dry placement across cracks in the masonry. The technique is applied on a masonry wall tested under quasi- static cyclic in-plane shear loading for the evaluation of its performance not only in the DL state for which it was conceived, but also in the NC states. The wall features artificially introduc, This research was funded by the Rijksdienst voor het Cultureel Erfgoed (RCE), part of the Ministerie van Onderwijs, Cultuur en Wetenschap (OCW), the Netherlands, subsidy No. MS-2018-189, which is gratefully acknowledged., Peer Reviewed, Postprint (published version)