Dissertations / Theses on the topic 'Masonry'

This dissertation examines the collapse of masonry structures in response to large support displacements and horizontal ground accelerations. There are two main classes of masonry structure: arches that thrust, and supporting elements, such as walls and buttresses, which resist the thrust. This dissertation analyses the safety of arches and buttresses and identifies the resulting collapse mechanisms due to support displacements or horizontal accelerations. In particular, this research investigates the stability of a masonry arch supported on buttresses and the conditions necessary for collapse to occur. Engineers are frequently asked to determine the safety of masonry structures that have been severely distorted over the years, often due to subsidence or other long-term movements in the foundations, and this dissertation provides guidance in the assessment of such structures. The resistance of masonry buttresses to high-level horizontal loads is examined. In the case of failure due to overturning, a fracture will develop in the masonry, significantly reducing the resistance of the buttress. The capacity is further reduced by outward leaning of the buttresses, a common source of distress for masonry structures due to movements in the supporting foundations. Based on these considerations, new measures of safety are proposed for buttresses under horizontal loading. Outward leaning of the buttresses increases the span of the arch or vault. Spreading supports will cause large deformations in the arch, which increase the horizontal thrust of the arch and may lead to collapse. In addition, lateral ground accelerations can cause the collapse of arches. The influence of seismic action can be approximated to first order by equivalent static analysis to determine the initial collapse mechanism. These problems are analysed for circular masonry arches, and the collapse conditions are identified for various geometries. The findings are combined to investigate the stability of the masonry arch supported on buttresses. The safety of the system is examined by studying the influence of imposed displacements. As the buttresses lean, the thrust of the vault increases and the resistance of the buttress decreases. The collapse mechanisms are identified for both the static case of leaning buttresses and the dynamic case of horizontal acceleration. This analysis illustrates that the arch will collapse and the buttresses will remain standing in most cases. Based on these considerations, new methods are proposed for assessing the safety of masonry structures and determining the influence of future movements on the stability of existing masonry structures.

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2009.
Includes bibliographical references (leaf 40).
Infrastructure in the United States is comprised of numerous structures that are decades old. The Longfellow Bridge is one of the oldest pieces of this infrastructure that is still in use and has become one of the most historic structures of the Boston area. Currently, the steel superstructure of the bridge is in poor condition while the masonry piers and abutments remain in good condition. In the near future, a major replacement of the superstructure will be required. In order for the masonry elements to be approved for a renewed design life, they must be assessed for their ability to withstand seismic loads. This assessment presents an investigation of original construction documents and identifies critical components of the bridge that require more in depth analysis. It also shows a qualitative review of expected seismic activity for the region surrounding Boston. A review of current theory related to unreinforced masonry structures is introduced and analysis is then performed on critical wall sections. Specific ground motions are applied using both constant acceleration and impulse loadings to the structure. The results of the analyses reveal a need for further investigation into retrofitting schemes as there is not a sufficient factor of safety that exists with certain pier elements. Furthermore, a failure envelope is developed and presented for several types of impulse loads in order to serve as a basis for understanding the behavioral response to potential earthquake loading.
by Nathan D. Boutin.
M.Eng.

The behaviour of concrete masonry under in-plane compression combined with out-of-plane bending was examined both experimentally and analytically. Ungrouted and grouted masonry, both fully bedded or face-shell bedded, were included in the study. It was found that the masonry under the above stated loading conditions may suffer loss of capacity either due to splitting or shear type of material failure, or by instability. Different loading conditions yield different failure mechanisms, which in turn correspond to different apparent strengths. Theoretical developments are presented leading to estimates of capacity for each of these cases. An extensive experimental program involving 104 masonry prism specimens, was conducted to assist and to verify these analyses. Theoretical developments include those directed to explain splitting failure phenomena, to investigate the mortar joint effect, the deformation compatibility of grouted masonry, and to examine the slenderness of tall masonry wall. Experimental measurements and observations made on the specimens include capacity, deformation and failure pattern.
Applied Science, Faculty of
Civil Engineering, Department of
Graduate

Masonry structures are especially vulnerable to earthquakes. Previous studies have focused mostly on their mechanical characteristics, while masonry structures vary greatly in terms of structural and material properties. This thesis aims to present the post-crack dynamic behaviour of masonry structures on mechanism. Systematic studies, including pseudo-static experiments, shaking-table experiments and mathematical modelling, were carried out. In the pseudo-static experiments, scaled masonry walls with different geometric forms, bond types and corner connections were tested. The static-phase in-plane and out-of-plane damage mechanisms of masonry walls were classified. Their load factors and the influence of structural configurations were discussed. Experimental load factors are compared with theoretical ones derived from a limit-analysis procedure. The shaking-table experiments successfully captured the dynamic-phase response mechanisms. Three 3D dry masonry models were tested according to sinusoidal excitation based on either constant amplitudes or constant peak accelerations. Conclusions on the dynamic behaviour of the masonry structure were presented. The experimental basis for the theoretical model was presented. The influence of structural configuration and excitation figure were clarified. The critical factors were clarified as being the excitation frequency and L/H ratio of the façade. The consistent damage behaviour variations arising from these two factors were analyzed. A nonlinear dynamic mathematical model for the rocking of the masonry façade was developed, using a two-rigid-body model. The loads and frictional force on the top were included, with a horizontal excitation being applied. Assumptions of rigid ground, inelastic impact and point contact were applied. Six possible patterns were defined. The rocking, the impact and the possible transitions were formulated. Models in the shaking-table experiments were simulated to evaluate this model. Parametric studies were performed and future works were recommended.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Architecture, 2006.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 121-123).
This thesis developed a new method to analyze the structural behavior of masonry domes: the modified thrust line analysis. This graphical-based method offers several advantages to existing methods. It is the first to account for the ability of domes to achieve a range of internal forces, gaining potentially an infinite number of equilibrium solutions that could not be derived otherwise. This method can also analyze non-conventional axisymmetrical dome geometries that are difficult or impossible to analyze with existing methods. Abiding by limit state conditions and the principles of the lower bound theorem, the modified thrust line method was used to ascertain the theoretical minimum thrust of spherical and pointed domes, a parameter that was previously unsolved. Several methods to estimate minimum thrust to-weight ratio were provided. For spherical domes, this ratio may be estimated as -0.583[alpha] + 1.123; for pointed domes, the estimated ratio is 0.551[delta] -1.061[delta]/[alpha] -0.615[alpha] + 1.164, where [alpha] and [delta] are the embrace and truncating angles, respectively.
(cont.) From the results, salient relationships between minimum thrust and dome geometry were derived, including an inverse relationship between the minimum thrust and the thickness-to-radius ratio, angle of embrace, and, for pointed domes, the truncation angle of the crown for a constant angle of embrace. The capabilities of the modified thrust line method were demonstrated in two masonry dome case studies that existing methods could not successfully analyze. The potential of this method to predict the ultimate load capacity of masonry domes was also explored. The method overpredicted the capacity of two small-scale masonry domes loaded to failure by a concentrated applied load at the crown; however the small size of the domes compared to real-world domes suggested that scale effects may have influenced their behavior. Finally, interactive geometry programs of the modified thrust line method and other existing graphical analysis methods were created to disseminate these illustrative tools to understanding the structural behavior of masonry domes.
by Wanda W. Lau.
S.M.

Thesis: M. Eng., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2016.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 59-60).
Earthquakes throughout the world can be devastating catastrophes, especially in developing nations. Confined masonry (CM) structures have proven to be a viable solution for seismic resiliency in the unique restraints and conditions of developing nations. CM provides benefits of increased shear capacity with smaller concrete frame members that provides economic benefit as well. However, the behavior of CM is highly non-linear during a seismic event and requires expertise to correctly model and analyze structures. A need for simplified guidelines are required for successful implementation of CM as a low cost solution for developing nations. The study parameterizes a simplified procedure for the design of CM buildings that takes into account irregularities and torsional effects in order to provide a tool to aid in the development of simplified design guidelines for CM. Different building configurations are sampled in geometric and material studies to provide recommendations for the design guidelines. The design guidelines are developed for the context of the Kathmandu Valley in Nepal to aid in their reconstruction efforts following the 2015 Gorkha earthquake. The parameters can be easily changed according to the country location to develop similar guidelines. Then a prototypic study on school buildings will show the structural and economic benefit of CM structures. Building shape typologies (L-, T-, and C-shaped plans) are explored in the geometric study. In the context of Nepal, only 3 story buildings have significant torsional effects. Design guidelines are recommended based on the building plan parameters. The material study aids in the understanding of the influence of wall thickness and brick strength. In the study, the increase in wall thickness and masonry compressive strength does decrease the utilization of the structure. However, there is a diminishing return and a limit on amount of improvement with the increase of both parameters. In an effort to contribute to the school sector as well, a prototypic study of approved school designs from Nepal is performed. While the approved school designs are for other material types (RC frame with brick infill, stone and mud, earthbag, etc.), the proposed architectural layout is maintained and analyzed as CM. Then the designs are compared with the same layout but a more economical design in CM. Saving in material quantities for the school building, the study shows that CM provides superior economic and structural benefits.
by Mark Bryant Membreño.
M. Eng.

Thesis (M. Arch.)--Massachusetts Institute of Technology, Dept. of Architecture, 2010.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 132).
This design-research thesis - The 4-Dimensional Masonry Construction - presents innovation in the design and construction of thin-shell tile vaulted structures. The core research contributions of this thesis are: #1 Testing limit states of unit hinging + displacement in single-layer tile vaults. #2 Introducing modified masonry units to achieve directional surfaces with high degrees of double-curvature and porosity. The 4-Dimensional Masonry Construction operates as a heuristic device to conceptualize, visualize and represent the way in which a masonry unit hinges in space within a complex, doubly-curved structural surface. By modifying masonry units, the resulting system of aggregation can produce asymmetrical and disaggregating tile coursing geometries - predictable yet geometrically incomprehensible systems. By establishing reciprocity between the modified unit/ system relation and the method of vault assembly, new forms in structural masonry are possible. Such structural forms are a product of these unique unit/ system geometries, the constraint of structural geometries (catenary systems and double curvature for lateral stiffness), the techniques of graphical analysis to define such a structure spatially, and the logic of sequencing to maintain the units' systematic relation, to constrain units inherently given to push the limits of constructibility.
by Lara K. Davis.
M.Arch.

The thesis comprises of 44 published papers mainly dealing with various aspects of structural masonry. The success of masonry and its use in high-rise buildings and other civil engineering works required better understanding of materials and its structural behaviour. The thesis describes the most comprehensive and systematic research investigation undertaken in the area of material science relevant to structure, structural performance and design methodology for plain, reinforced and prestressed masonry. Novel test methods for obtaining tensile strength of individual brick and bi-axial strength of masonry in flexure are described. Several series of full-scale tests to investigate the behaviours of brickwork subjected to combined compression and shear, multi-storey brick shear wall structure subjected to wind loading, progressive collapse, lateral strength of wall panels with and without precompression, interaction between wall and floor slabs are also described. Based on the tests of real structures, design methods for multi-storey masonry structures subjected to vertical and wind loading, and to limit the progressive collapse due to accidental loading are recommended. A Coulomb type of equation is suggested to calculate the ultimate shear strength of masonry. A theory to predict the lateral strength of masonry subjected to precompression has also been described. Methods developed to predict the shear and flexural strengths of reinforced and prestressed masonry are elucidated. A plastic method, similar to concrete, is used for the theoretical prediction of the shear strength of prestressed beams. An analytical technique for calculating the load-deflection and the ultimate moment capacity of reinforced and prestressed sections is also presented. The technique takes into account all the sources of non-linearity; such as non-linear material behaviour, cracking and tension stiffening.

The objective of the research programme has been to investigate the behaviour of masonry arch vault collapse mechanisms in the context of the problems besetting the national bridge stock. The programme has primarily involved masonry constitutive theoretical studies, supported by laboratory experimentation, which have led to the formulation of novel masonry hinge modelling. The modelling has been developed for practical application in a four hinge masonry vault mechanism analysis and subjected to testing. The technique has been applied in the field supported by a novel application of information technology (IT) image processing, reflecting the growing importance of IT within the construction industry. All theoretical studies have been mounted as micro-computer software with graphics. The accent is upon engineering requirements in practice. Chapter One reviews the context and history of the masonry vault structural form, whose presence has long been commonplace in the United Kingdom, especially on the nation's road network. It is noted that elderly arched road bridges are under continual pressure to carry ever greater loads yet their strength is uncertain. Historically, structural analysts have attempted to resolve the arch's behaviour but present methods are still inexact. Chapter Two describes how, traditionally, masonry has been assumed to possess either a linear stress-strain property or infinite stiffness and strength. An alternative, novel equation for modelling masonry stress-strain laws is presented which may be configured to mimic the behaviour of real materials as well as that of the infinite strength and linear laws it replaces. A numerical analytical procedure has been developed to 'solve' rectangular masonry sections under combined bending and thrust thereby rendering the earlier approximations unnecessary. Chapter Three develops the theme further leading to the numerical determination of limit state hinge characteristics which furnish a static limit state axial thrust/bending moment interaction diagram and a corresponding serviceability limit state, prevention of cracking interaction diagram. Differentiation is thus made possible between hitherto identically-treated though varying natural materials and comparisons made. It is further postulated that any point on a static limit state interaction diagram locus represents a masonry hinge and an extensive series of laboratory model hinge tests is undertaken to demonstrate the point by testing the foregoing theoretical studies. Chapter Four describes the incorporation of the hinge theory into a mechanism-type computer analytical tool. Crucially, the analysis is different from other mechanism analyses by virtue of the hinge modelling, enabling the effects of material properties on arch behaviour to be studied. The software is tested in Chapter Five against prototype data for laboratory model and full size masonry bridges. Chapter Six introduces computer vision, an IT technique that is relatively novel to the structures field. It is adapted to monitor the above laboratory model arch tests and then extended to the monitoring of a multi-span arch bridge test in the field. Computer vision permits the formulation of a hypothesis regarding the unusual mode of failure that occurred and this is supported by a generalisation of the mechanism hinge theory, thereby demonstrating the merits of both techniques. Finally, Chapter Seven draws conclusions on the foregoing and makes suggestions for further work. Supporting documentation is given in the Appendices.

The aim of the present research was to provide a practical theoretical model based on elementary statics, for assessment for masonry arch bridges, that benefits from the large scale experimental programme at Salford University, together with insight gained from the Distinct Element numerical modelling work. The need for large scale laboratory controlled load tests of physical models that may be reliably confined to a specific domain of behaviour with known parameters and modelling constraints, was highlighted in chapter 2 with reference to literature. Load tests on various distributions of surcharge were carried and the mechanisms of failure observed. The numerical modelled was shown to agree with expected theoretical behaviour and shown good agreement with experimental results. A theoretical model was developed which benefitted from insight from the experimental and numerical work to provide a means of predicting the failure load of the arch-fill system for the lading arrangements carried out in the physical and numerical tests. The model provided predicted failure loads for a range of material variation within a reasonable expected range and showed promising resemblance to the physical modelling results.

Masonry spires are a typical part of church architecture. Since it is rare that masonry is used as a load-bearing material in the western world today, it is important to maintain and increase the knowledge of modelling masonry structures both from a maintenance point of view and to build new masonry structures. The purpose of this master thesis is to look at and evaluate some different methods to model masonry spires exposed to common loads such as gravity, settlement and wind. The spire of the Salisbury Cathedral is used as a template regarding geometry and mechanical properties for the modelling methods. Two modelling methods are used in the master’s thesis. The first one is the limit analysis method applied to masonry. It is used to calculate a critical thickness for the masonry of the spire for a severe wind load. The second method is the Finite Element Method (FEM). The commercial finite element software Abaqus is used to create the model and the discretization used with the FE modelling is the macro-modelling approach. Concrete Damage Plasticity (CDP) in Abaqus is used as the material model and adapted to masonry. The finite element model consists of the spire itself along with the supporting structure beneath it down to the piers. Four different simulations (jobs) are run with varying wind direction and two of them have settling piers. The results from the finite element simulations indicate that the membrane stresses in the spire faces for the various jobs were not significantly different from one another. One of the jobs with settling piers could not be completed because the tensile stresses in the arches reached the tensile strength capacity of the material. The other simulation with a settlement that did complete did not have any significant difference in stress compared with the simulations without settlements. While the arches and the piers underwent plastic straining the spire itself did not. The stress levels there remained in the linear range for all the completed simulations. The finite element results also agree with the limit analysis. These findings call into question some of the modelling choices. The inclusion of the structure beneath the spire in the finite element model, as a way to study the effect of settlements, did not give more insight into the spire’s behaviour. Furthermore, the method to implement settlements was too inaccurate and another approach should be used to study the effect of settlements on the state of spires. Further work needs to be done on that topic. Improvements can also be made regarding how CDP was adapted for masonry.
Murade tornspiror är en vanlig takkonstruktion inom kyrkoarkitekturen. Eftersom det numera är sällsynt att murverk fungerar som lastbärande material i västvärlden, är det viktigt att upprätthålla och utöka kunskapen om murverkskonstruktioner för både underhåll och nybyggnation. Syftet med denna masteruppsats är att betrakta och utvärdera några olika modelleringsmetoder för murade tornspiror som är utsatta för några typiska laster såsom egentyngd, sättningar och vind. Katedralen i Salisbury används som en modelleringsmall i uppsatsen med avseende på katedralens geometri och materialegenskaper. Två modelleringsmetoder används i uppsatsen. Den första är gränsanalys tillämpad på murverkskonstruktioner. Den används för att beräkna en kritisk tjocklek för tornspiran under en stor vindlast. Den andra metoden är Finita Elementmetoden (FEM). Den kommersiella finita elementprogramvaran Abaqus används för finita elementanalysen och diskretiseringen som används för murverket i finita elementmodellen är makromodellering. Concrete Damage Plasticity (CDP) i Abaqus används som materialmodell och anpassas för murverk. Finita elementmodellen består utav själva tornspiran inklusive de bärande delarna under spiran och ned till pelarna. Fyra olika simuleringar ("jobb") körs med vindlast som angriper från olika riktningar och två av simuleringarna har pelare som sätter sig. Resultaten från simuleringarna visar att membranspänningarna i tornspirans väggar, för de olika jobben, inte skilde sig i någon betydelig grad från varandra. Ett av jobben med pelare som satte sig kunde inte köras klart eftersom dragspänningarna i valvbågarna överskred draghållfastheten på murverket i modellen. Den andra simuleringen med sättningar som kördes klart uppvisade inte några avsevärda skillnader i spänningar i tornspiran jämfört med simuleringarna utan sättningar. Medan plastiska töjningar uppkom i både valvbågarna och pelarna i modellen, uppkom de inte i tornspiran. Spänningsnivåerna i tornspiran var inom det linjära intervallet för alla simuleringar. Resultaten från finita elementanalysen stämde överens med resultaten från gränsanalysen. Analysresultaten ifrågasätter vissa av modelleringsvalen. Att inkludera de bärande delarna under tornspiran i finita elementmodellen, för att undersöka effekten av sättningar, gav inte en större insikt i hur sättningar påverkar tornspiran. Dessutom, var metoden för att tillämpa sättningar för oprecis och en annan metod borde användas. Mer arbete måste utföras vad gäller det ämnet. Sättet att tillämpa CDP för murverk kan också förbättras.

In January 1999, the maximum axle weight increased from IN to 11.5t for the assessmenot f highway bridges and structures. At the samet ime, the maximum vehicle weight also increased from 38t to 44t. Highway authorities are urgently searching for a more refined assessmenmt ethod to predict the behaviour of masonry arch bridges. LUSAS finite element analysis was used to study the behaviour of masonry arch bridges. Load versus deflection curves and collapse loads are given for some of the full and large scale arches previously tested to collapse. A parametric study was also performed to determine the influence of the arch material properties and the load dispersal angle: the arch tensile strength and the load dispersal angle were found to have the most significant influence on the collapse load predictions. Repeatability tests were carried out by building three nominally identical large scale arch bridges in the laboratory and testing them to collapse. The first, second and third arches collapsed at 2lkNm', 16kNm', and 25kNm 1 respectively. Finite element analysis predicted a range of 18kNm' to 39kNm 1 for the same arches. This led to an examination of a statistical, risk based, approach to bridge assessment. Two novel risk assessment programs were developed by integrating Monte Carlo simulation with the MEXE and the mechanism methods. Statistical information about the predicted collapse load and allowable axle load is given. These risk assessment tools are offered for incorporation within routine assessmenmt ethods. Their principal benefit lies in providing engineers with a feel for the reliability of their analyses. A modification has been made to the mechanism method by considering arch deflection. A mechanism prediction is accurate only when all the forces and their positions are accurately located. The modified mechanism method was used to analyse some of the full scale arch bridges, previously tested to collapse, which revealed that arch deflections had a significant influence on the collapse load prediction.

The recycling of demolished masonry rubble as the coarse aggregate in new concrete represents an interesting possibility at a time when the cost of dumping such material is on the increase. With growing concerns over the environmental impact of aggregate extraction and the continued rise in aggregate demand in the UK, it is clear that the market is now there for recycled and secondary aggregates. The present investigation consists of experimental and theoretical studies into the effects of using recycled aggregates to produce concrete instead of virgin aggregates. The aggregates used have been recycled from construction and demolition waste. The recycled aggregates were predominately made up of crushed bricks but the aggregates did contain impurities such as timber and mortar. New bricks were crushed to form an aggregate in order to investigate the properties of brick as a material without impurities. The physical properties of the various aggregates were firstly examined and compared with granite aggregate, an aggregate proven in the production of good quality concrete. Concrete was then produced with the aggregates and all the physical and mechanical properties of the concretes were examined in some detail. The results showed that recycled masonry aggregates can be used successfully to produce· concrete of an acceptable standard. New test methods were presented in this investigation to determine brick porosity and water absorption. This involved the testing of broken brick fragments under vacuum, rather than the testing of whole brick units by 5hrs boiling or 24hrs submersion in cold water. The new test methods proved to be easy to perform and provided accurate results. A new test method for estimating the strength of bricks was presented. This involved point-loading of masonry specimens to obtain strength index values. From the pointload results, equations were presented relating the strength index values of brick fragments to the compressive strength of whole brick units. This involved the development of shape factors for different masonry specimens. The point-load test is easy to perform, presents a cheaper alternative to heavy compression machines and can be used on site to determine the suitability of recycled bricks as the aggregate in new concrete.

Master of Science
Architectural Engineering and Construction Science
Kimberly W. Kramer
The term hybrid masonry describes three variations of a lateral force resisting system that utilizes masonry panels inside steel framing to resist lateral loads from wind or earthquakes. The system originates from the rich history of masonry in the construction industry and is currently used in low-rise, low-seismic, wind-governed locations within the United States. Considerable research is focused on hybrid systems to prove their validity in high-seismic applications. The three variations of hybrid masonry are known by number. Type I hybrid masonry utilizes the masonry panel as a non-load-bearing masonry shear wall. Shear loads from the diaphragm are transferred into the beam, through metal plates, and over an air gap to the top of the masonry panel. The masonry panel transfers the shear to the beam below the panel using compression at the toe of the wall and tension through the reinforcement that is welded to the beam supporting the masonry. Steel framing in this system is designed to resist all gravity loads and effects from the shear wall. Type II hybrid masonry utilizes the masonry as a load-bearing masonry shear wall. The masonry wall, which is constructed from the ground up, supports the floor live loads and dead load of the wall, as well as the lateral seismic load. Shear is transferred from the diaphragm to the steel beam and into the attached masonry panel via shear studs. The masonry panel transfers the seismic load using compression at the toe and opposite corner of the panel. Type III hybrid masonry also utilizes the masonry panel as a load-bearing masonry shear wall, but the load transfer mechanisms are more complicated since the panel is attached to the surrounding steel framing on all four sides of the panel. This study created standard building designs for hybrid systems and a standard moment frame system with masonry infill in order to evaluate the validity of Type I and II hybrid masonry. The hybrid systems were compared to the standard of a moment frame system based on constructability, design, and economics.

Masonry is an ancient building material that has been used throughout the history, and it is still used nowadays. Masonry constitutes the main building technique adopted in historical constructions, and a deep understanding of its behavior is of primary importance for the preservation of our cultural heritage. Despite its extensive usage, masonry has always been used following a trial and error approach and rules-of-thumb, due to a poor understanding of the complex mechanical behavior of such a composite material. Advanced numerical methods are therefore attractive tools to understand and predict the behavior of masonry up to and including its complete failure, allowing to estimate the residual strength and safety of structures. Several numerical methods have been proposed in recent years, either based on a full micro-modeling of masonry constituents, or on phenomenological macro models. In-between these two approaches, computational homogenization techniques have recently emerged as a promising tool joining their advantages. The problem is split into two scales: the structural scale is treated as an equivalent homogeneous medium, while the complex behavior of the heterogeneous micro-structure is taken into account solving a micro-scale problem on a representative sample of the micro-structure. The aim of this research is the development of a computational multiscale homogenization technique for the analysis of masonry structure, subjected to quasi-static in-plane and out-of-plane loadings. Classical Cauchy continuum theory is used at both scales, thus using the so-called first order computational homogenization. Due to the brittle nature of masonry constituents, particular attention is given to the problem of strain localization. In this context, the present research proposes an extension of the fracture-energy-based regularization to the two-scale homogenization problem, allowing the use of first order computational homogenization in problems involving strain localization. The method is first stated for the standard continuum case, and it is applied to the two-dimensional analysis of in-plane loaded shear walls made of periodic brick masonry. Then, the aforementioned method is extended to the case of shell structures for the analysis of out-of-plane loaded masonry walls. For this purpose, a novel homogenization technique based on thick shell theory is developed. Both in the in-plane and in the out-of-plane loading conditions, the accuracy of the proposed method is validated comparing it with experimental evidences and with micro-model analyses. The regularization properties are also assessed. The obtained results show how computational homogenization is an ideal tool for an accurate evaluation of the structural response of masonry structures, accounting for the complex behavior of its micro-structure.
La obra de fábrica es un material de construcción tradicional que ha sido utilizado a lo largo de la historia y que sigue siendo utilizado hoy en día. La obra de fábrica constituye la principal técnica de construcción adoptada en estructuras históricas, y una comprensión profunda de su comportamiento es de vital importancia para la conservación de nuestro patrimonio cultural. A pesar de su amplio uso, la obra de fábrica ha sido utilizada frecuentemente adoptando un enfoque empírico, debido a un escaso conocimiento del comportamiento mecánico complejo de este tipo de material compuesto. Los métodos numéricos avanzados son herramientas atractivas para entender y predecir el comportamiento de la obra de fábrica hasta su fallo, permitiendo estimar la resistencia residual y la seguridad de las estructuras. Durante los últimos años, han sido propuestos diferentes modelos computacionales, basados bien en una micro-modelización completa de los constituyentes del material (ladrillos y juntas de mortero), o bien en macro-modelos fenomenológicos. A partir de estos dos enfoques, los métodos de homogenización computacional han emergido recientemente como una herramienta prometedora que puede combinar las ventajas de la micro- y macro-modelización. El problema se divide en dos pasos: la escala estructural se trata como un medio homogéneo equivalente, mientras el comportamiento complejo de la microestructura heterogénea se tiene en cuenta mediante la resolución de un problema micro-mecánico reconducible a una muestra representativa de la microestructura. El objetivo de esta investigación es el desarrollo de una técnica de homogenización computacional multi-escala para el análisis de estructuras de obra de fábrica sometidas a cargas horizontales cuasi-estáticas que actúan en el plano y fuera del plano. Se adopta la teoría clásica del medio continuo de Cauchy en ambas las escalas, utilizando así la homogeneización computacional del primer orden. Debido a la naturaleza frágil de los componentes de la obra de fábrica, el estudio contempla también el problema de la localización de la deformación en el marco del enfoque numérico de fisura distribuida. En este contexto, la presente investigación propone una extensión de la regularización basada en la energía de fractura para el problema de homogenización en dos escalas, permitiendo el uso de la homogenización computacional del primer orden en problemas que implican la localización de la deformación. El método se plantea en primer lugar para el caso continuo general, y a continuación se aplica al análisis de muros de corte cargados en su plano y hechos de fábrica de ladrillos con aparejo periódico. Posteriormente, el método se extiende al caso de estructuras tipo placa para el análisis de muros de obra de fábrica cargados fuera de su plano. Para este propósito, se desarrolla una nueva técnica de homogenización basada en la teoría de placas gruesas. En ambos los casos de carga en el plano y fuera del plano, la precisión del método propuesto se valida mediante la comparación con ensayos experimentales y análisis de micro-modelización. También se validan las propiedades de regularización. Los resultados obtenidos muestran cómo la homogeneización computacional pueda resultar una herramienta válida para una evaluación precisa de la respuesta estructural de las estructuras de obra de fábrica, teniendo en cuenta el comportamiento complejo de la micro-estructura.
La muratura è un antico materiale da costruzione che è stato utilizzato in special modo nel corso della storia, ma che è ancora oggi piuttosto diffuso. La muratura è la tecnica principale di costruzione adottata in edifici storici, e una profonda comprensione del suo comportamento è di vitale importanza per la conservazione del nostro patrimonio culturale. Nonostante il suo ampio utilizzo, la muratura è sempre stata utilizzata seguendo un approccio empirico, a causa di una scarsa comprensione del complesso comportamento meccanico di tale materiale composito. I metodi numerici avanzati sono, quindi, strumenti attraenti per studiare e comprendere il comportamento della muratura fino al suo collasso, permettendo di stimare la resistenza residua e la sicurezza delle strutture. Diversi metodi numerici sono stati proposti negli ultimi anni, basati o sulla completa micro-modellazione dei componenti della muratura (mattoni e giunti di malta), o su macro-modelli fenomenologici. A metà strada tra questi due approcci, le tecniche di omogeneizzazione computazionale sono emerse recentemente come uno strumento promettente che unisce i vantaggi della micro- e macromodellazione. Il problema viene diviso in due scale: la scala strutturale viene trattata come un mezzo omogeneo equivalente, mentre il complesso comportamento della microstruttura eterogenea viene preso in considerazione risolvendo un problema di micro-scala su un volume rappresentativo della microstruttura. Lo scopo di questa ricerca è lo sviluppo di una tecnica di omogeneizzazione computazionale multiscala per l’analisi di strutture in muratura, sottoposte a carichi orizzontali quasi-statici agenti nel piano e fuori dal piano. La teoria classica del continuo di Cauchy è adottata in entrambe le scale, utilizzando quindi la cosiddetta omogeneizzazione computazionale del primo ordine. A causa della natura fragile dei costituenti della muratura, particolare attenzione viene dedicata al problema della local-izzazione delle deformazioni nel modello numerico a danneggiamento distribuito. In questo contesto, la presente ricerca propone un’estensione della regolarizzazione basata sull’energia di frattura al problema di omogeneizzazione a due scale, permettendo l’uso dell’omogeneizzazione computazionale di primo ordine in problemi che coinvolgono localizzazione delle deformazioni. Il metodo viene prima impostato per il caso continuo generale, e viene in seguito applicato all’analisi bidimensionale di pareti a taglio, caricate nel piano, fatte di muratura di mattoni a disposizione periodica. Poi, il suddetto metodo viene esteso al caso di strutture tipo piastra per l’analisi di pareti in muratura caricate fuori dal piano. A questo scopo, si sviluppa una nuova tecnica di omogeneizzazione basata sulla teoria delle piastre spesse. In entrambi i casi di carico nel piano e fuori dal piano, l’accuratezza del metodo proposto è validata mediante il confronto con evidenze sperimentali e con analisi di micro-modellazione. Allo stesso modo, le proprietà di regolarizzazione vengono validate. I risultati ottenuti evidenziano come l’omogeneizzazione computazionale sia uno strumento valido per una valutazione accurata della risposta strutturale delle strutture in muratura, tenendo conto del comportamento complesso della sua microstruttura.

This thesis focuses on the seismic performance of unreinforced masonry wall perforated with a door opening representing typical URM walls of many aged masonry buildings in Indonesia. To obtain a test result that will be able to represent the local conditions, the experiments have been conducted in the Research Institute for Human Settlements (RIHS) laboratory in Bandung-Indonesia. Two 75 % unreinforced masonry (URM) walls with a 1½-wythe of solid clay-brick were constructed in Dutch bond configuration and tested until failure under quasi-static-reversed cyclic loading. Both units were loaded vertically by constant loads representing gravity loads on the URM wall’s tributary area. Both models were constructed using local materials and local labours. Two features were taken into account. First, it accommodated the influence of flanged wall and second, the URM wall was built on the stone foundation. The first URM wall represent the plain existing URM building in Indonesia and second strengthened by Kevlar fibre. It was observed from the test results that the URM wall Unit-1 did not behave as a brittle structure. It could dissipate energy without loss of strength and had a post-elastic behaviour in terms of “overall displacement ductility” value of around 8 to 10. As predicted, the masonry material was variable and non homogeneous which caused the hysteresis loop to be non symmetrical between push and pull lateral load directions. It can be summarized that Kevlar fibre strengthening technique is promising and with great ease of installation. Although Kevlar material is more expensive when compared to other fabrics as long as it was applied at the essential locations and in limited volumes, it can significantly increase the in-plane URM wall capacity. With appropriate arrangements of Kevlar fibre, a practicing engineer will be able to obtain a desired rocking mechanism in the masonry structure. Another advantage for the architectural point of view, very thin Kevlar fibres do not reduce the architectural space. Studies have also been undertaken to analyze the in-plane response of plain URM wall before and after retrofiting using the current seismic standard and the Finite Element Method (FEM).

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Architecture, 2009.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 181-189).
Masonry structures are vulnerable to earthquakes, but their seismic assessment remains a challenge. This dissertation develops and improves several strategies to better understand the behavior of masonry structures under seismic loading, and to determine their safety. The primary focus is on historic arched or vaulted structures, but more modern unreinforced masonry structures are also considered. Assessment strategies which employ simplified quasi-static loading to simulate seismic effects are initially addressed. New analysis methods which focus on stability or strength are presented, and the merits of these strategies are clarified. First, a new parametric graphical equilibrium method is developed which allows real-time analysis and illuminates the complex stability of vaulted masonry structures. Second, a finite element strategy for predicting brittle fracture of masonry structures is extended to incorporate non-proportional loading and shell elements. These extensions enable prediction of damage and collapse mechanisms in general, but are specifically used to predict the response of a full-scale masonry structure to quasi-static cyclic loading. Subsequently, assessment methods based on the dynamic response of masonry structures under earthquake loading are presented. First, rigid body dynamics and an experimental testing program are used to characterize the rocking response of the masonry arch for the first time.
(cont.) An assessment criterion is developed which successfully predicts experimentally observed arch collapse under a variety of earthquake time histories. Second, the behavior of rocking structures is addressed in general, and clearly distinguished from typical dynamic oscillators. The rocking response is time dependent, evoking the development of a statistical method for predicting collapse. Finally, the ability of discrete element methods to predict the dynamics of masonry structures is evaluated through comparison with analytical and experimental results, and a rational method for assigning modeling parameters is proposed.
by Matthew J. DeJong.
Ph.D.

Thesis: M. Eng., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2016.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 53-54).
This thesis investigates the viability of shallow, unreinforced masonry domes for the roof and floor systems of residential construction. In recent years, reinforced concrete (RCC) framed construction has been established as the dominant structural form for residential and commercial usage in the developing world, with the flat two-way slab as the most common (almost universal in northern India) spanning solution for these designs. Over the same time period, local artisans in the Muzzafarnagar region of Uttar Pradesh in northern India have combined shallow brick vaulting techniques with an RCC tension ring as a small to medium scale spanning solution. While these vaults are a cost-effective alternative to a concrete slab roof/floor system, improperly designed and detailed masonry construction can prove dangerous, especially in seismic zones. This thesis is an exploration of the structural behavior and design of these domes, intended to produce broadly applicable design guidelines to ensure the strength and stability of this structural typology in order to valorize their broad usage, where appropriate, in India's housing sector. Simplified design calculations for unreinforced masonry which match experimental data are generated using equilibrium methods and plastic design theory. Influence of geometric and material parameters on strength and stability are investigated, and discussion of proper detailing and the limitations of this spanning technology is included.
by Samuel Hodin Wilson.
M. Eng.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Architecture, 2005.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (leaves 38-40).
This thesis presents new interactive computational analysis tools for masonry structures based on limit state analysis. Thrust lines are used to clearly visualize the forces within the masonry and to predict possible collapse modes. The models are interactive and parametric to explore the relation between the different geometrical parameters and the possible equilibrium conditions. Collapse mechanism analyses are determined by combining kinematics and statics. Complex three-dimensional problems are analyzed using the same methods. This thesis presents a series of analysis tools that are fast and easy to use, but at the same time rigorous and highly accurate.
by Philippe Block.
S.M.

Masonry arch bridges continue to play an important role in the UK's transport infrastructure, forming a significant proportion of road, rail and waterway crossings. Many of these bridges are relatively old and are still in service in their original configuration. Increasing vehicle loads and speeds have highlighted the need for reliable estimates of both ultimate and serviceability load levels. Most experimental work and assessment methods have so far been carried out under ultimate load. Only limited work has been undertaken to date on serviceability assessment methods, this project therefore aims to develop a systematic method to assess the serviceability load of masonry bridges under a series of different serviceability criteria. A complex spreadsheet was developed as the main analytical tool for the serviceability assessment and was an encastered elastic analysis based on Castigliano's complementary energy method. The geometric data from a large number of real masonry bridges data was gathered and analysed to develop suitable distribution statistics. Three independent serviceability criteria were then developed based on an attempt to replicate, on average, the existing assessment methods. These three criteria are stress, deflection and cracking depth. Finally, a serviceability assessment method system was fully established within the developed spreadsheet.

The teaching of the user through the clear understanding of the building they encounter on a daily basis is the intent of this thesis. Can a user learn how a brick wall is constructed, by looking and interacting with the brick wall they sleep within at night? Is it easier for one to understand his/her built environment if the construction is done in a manner that makes the means transparent, versus hidden tricks within the materials. Through the study of honest and truthful use of materials and construction methods, this project explores if a building can teach.
Master of Architecture

This study focuses on the evaluation of seismic safety of masonry buildings in Turkey by using fragility curves. Fragility curves for masonry buildings are generated by two behavior modes for load bearing walls: in-plane and out-of-plane. By considering the previous research and site investigations, four major parameters have been used in order to classify masonry buildings with in-plane behavior mode. These are number of stories, strength of load-bearing wall material, regularity in plan and the arrangement of walls (required length, openings in walls, etc.). In addition to these four parameters, floor type is also taken into account for the generation of fragility curves by considering out-of-plane behavior mode. During generation of fragility curves, a force-based approach has been used. In this study there exist two limit states, or in other words three damage states, in terms of base shear strength for in-plane behavior mode and flexural strength for out-of-plane behavior mode. To assess the seismic vulnerability of unreinforced masonry buildings in Turkey, generated fragility curves in terms of in-plane behavior, which is verified by damage statistics obtained during the 1995 Dinar earthquake, and out-of-plane behavior, which is verified by damage statistics obtained during the 2010 Elazig earthquake, is combined. Throughout the analysis, ground motion uncertainty, material variability and modeling uncertainty have also been considered. In the final part of the study, a single-valued parameter, called as &lsquo
vulnerability score&rdquo
, has been proposed in order to compare the seismic safety of unreinforced masonry buildings in Fatih sub province of Istanbul and to assess the influence of out-of-plane behavior together with the in-plane behavior of these existing masonry buildings.

In order to apply Sprayable Eco-Friendly Ductile Cementitious Composites (EDCC) as a thin overlay material for masonry building upgrade, this study aims at understanding one of the key issues of repair: bond strength between old structure and the new repair overlay. Several influencing factors on bond strength were investigated, including repair thickness, fiber addition, substrate properties, curing age and environment. Bond strength was measured by tensile pull-off and friction-transfer tests. At the conclusion of the research, EDCC was able to achieve satisfactory bond strength provided sufficient penetrability into the substrate, even under field conditions and without curing. Fibers added into EDCC impact bond strength negatively, if they are oriented parallel to the interface as a result of manual casting or if there is a low fractal dimension of the substrate surface. Further, 56 days can be used as the maturity age of bond strength with EDCC overlay. In future applications, penetrability of EDCC overlays can be ensured through sufficient amount of superplasticizer or energy of casting. For example, EDCC with 150mm slump was able to satisfy standard bond strength requirement of concrete in the field, at the age of 45 days. Penetrability of EDCC overlay is of vital importance, since EDCC with low workability (0 slump) can’t achieve requirement of structural repair even under standard curing. To mitigate the negative effect of fiber addition on bond strength, higher substrate roughness and 3D fiber orientation can be of help, through proper surface roughness preparation and the use of spray methods (e.g., shotcrete) instead of hand application. For further study, it is suggested that measures should be taken to obtain more pure bond strength values for simplification of analysis. Also surface roughness variation and long term properties of interface are worth investigation, once proper substrates are chosen for lab research.
Applied Science, Faculty of
Civil Engineering, Department of
Graduate

Most masonry arch structures behave as complex 3-dimensional structures. For the convenience of the analyst such structures are usually modelled as 2-dimensional structures with the effects of their 3-dimensional characteristics being taken into account by modifying the arch parameters and the output of the analysis. The thesis outlines a research programme which fundamentally attempts to model the 3-dimensional nature of 'real' arches. An experimental programme comprising tests on skew multi-ring brickwork arch ribs and point loading of a multi-ring brickwork square span arch with an aspect ratio of 1.25 is used to validate the modelling. The thesis will present the results from the laboratory tests. Class 'A' engineering bricks with 1:2:9 lime mortar were used to construct the two ring arch ribs. A skew angle of 45 was adopted with a square span between the interfaces of the supports of 3 metres. The square span to rise ratio was 4. The ribs were approximately 670 wide. Headers were provided to prevent ring-separations and the English method of skew arch constructions was used which resulted in the mortar bedding planes being square to the elevation at the crown and inclined to the abutments at the springings. Three-dimensional macro-models are used to simulate both the large-scale square arch tests and the two skew arch tests. The results of each of the FE analyses are compared with data obtained from the corresponding experiments. Reasonable agreement between FE analyses and experimental results has been obtained. The values and applicability of the research in engineering practice have been demonstrated.

The development of a computational model for low bond strength brick masonry is described. Cracking and failure in such masonry occurs typically at the interface between the masonry units and the mortar joints. As a result software based on a 2- dimensional discrete element analysis (UDEC) was used. One feature of the research was the method used to identify the material parameters for the constitutive model. The conventional method of obtaining material parameters from the results of testing small samples of masonry was thought to be problematic. Instead, the material parameters were obtained from the results of tests carried out in the laboratory on single leaf wall panels, each containing a large opening. Each panel was subjected to a gradually increasing vertical in-plane static point load until it collapsed. The wall panel tests were also modelled using UDEC. An optimization procedure was then used to tune the parameters used initially in UDEC in order to better simulate the pre- and post-cracking behaviour and the behaviour close to collapse of the panels tested in the laboratory. Having obtained the material parameters for UDEC, the model was then validated by comparing the UDEC-predicted behaviour of wall panels different to those used to determine the material parameters, with those tested in the laboratory. Some of the panels used for the validation process were reinforced with bed joint reinforcement, others were unreinforced but were of deeper and longer span construction. Good correlation was obtained between the results from the computational model and those obtained from tests in the laboratory.

In contrast to concrete, masonry is a complex inhomogenous material, which exhibits distinct directional properties due to the presence of mortar joints. In the past, both finite element and discrete element techniques have been used for modelling of masonry structures. However, no comparison of these two different approaches has been made. In this study, to achieve a fundamental insight into the behaviour of masonry structures, a series of numerical analyses have been carried out using Finite and Discrete Element methods for structures such as shear walls with/out opening, masonry panel under point load, and masonry arches. In Discrete Element analyses, bricks were modelled as conventional continuum elements, while an interface contact law (instead of mortar joints) was used to capture masonry failure mechanisms in the 2D plane-strain analyses. The contact law included softening in tension, shear and compression modes. In Finite Element modelling of the same structures, separate continuum elements were used for both constituents, i.e. the brick and mortar. The results were compared with experimental data. Both methods were able to reproduce the complete deformation pattern of the structures up to and beyond the peak until total degradation of strength, without major numerical difficulties. Parametric studies of the above problems have also been carried out to demonstrate the crucial role of some of the parameters. Comparative studies using the Finite Element and Discrete Element methods have shown that collapse load as well as mechanisms of failure are significantly influenced by the choice of interface parameters used in the Discrete Element method. These parameters are also difficult to determine from experiments. On the other hand, Finite Element analyses indicate lesser influence of parameters of the constituents and no anomalies arise in their choice from experimental data.

The main objective of this research is to develop a numerical model for the analysis of frost damage to masonry and implement it in a program for 3-dimensional analyses of masonry structures using the finite element method. It is shown that the standard FE approach in analysing masonry structures is not economical, so a homogenization technique was used to substitute composite masonry material with an equivalent homogeneous one. Parametric studies of relationships of property between constituents and the equivalent material are presented together with validation of the procedure. Masonry, or its constituents, is treated as a brittle material with a tensile cut-of failure criterion. Again, in order to achieve more computational efficiency, homogenization technique is used to represent cracked material. A set of freeze-thaw tests are described which are important in detecting the most influential factors controlling frost durability of masonry. Models of frost action are investigated on a micro scale - scale of individual pores. A stochastic network model is developed with an aim to investigate permeability characteristics of the porous material. The results of these calculations are used in providing information necessary to calculate stress due to the frost action. Typical examples of frost damage to masonry are simulated showing good agreement with the expected results. The following conclusions are drawn: * The major cause of damage to masonry is the expansion of water on its phase change from a fluid to a solid phase in the 'sealed container' conditions. * Micro structural properties of the material are the most important single factor in deciding the amount of internal loading on the material matrix caused by ice formation. In order to calculate this loading simulation of the process on the micro scale is required. * It is confirmed that a high fraction of small pores in the porous structure causes higher level of frost susceptibility.

This thesis is concerned about the development of computer data base management system for the assessment of masonry bridges. The various techniques of assessment and remedial measures of masonry bridges are outlined, their shortcomings described. A justification for an alternative method of assessment is given. A review of computer data base management systems is carried out. The reasons for adopting data base management systems is given as well as the reasons for choosing a particular type of data base management system. The common faults associated with masonry structures are described and the problems of identifying these faults are described. The part played by the individual components of a masonry arch bridge is given and the significance of faults on the individual components of the structure is described. A detailed description of the type, in general of the data base system chosen is given followed by a detailed description of a special case of the type chosen, which is the system that was used for the project. A description of how the system was developed is given followed by the way the system operates. A detailed description of how the system can be used is then put forward and the problems associated with the development of the system are outlined. Finally, a description of the implications of the system to the practising engineer is given.

This thesis investigates the design of masonry shell structures. Design is understood to involve two main processes; the first one is the specification of shape, form, and thickness, and the second is the justification of such choices through the analysis of its behaviour. The thesis is therefore introduced by an extensive literature review of, first of all, the relevant material properties, such as strength, stiffness, anisotropy, and bi-axial stress states, as well as of some interesting construction techniques, based on minimal or no formworkthe premise being that the contemporary adoption, or otherwise, of masonry shells as a feasible structural solution depends on the "economics" of the construction process. The analysis of the strength of masonry arches and shells is reviewed extensively, with considerable emphasis given to the validity of the application of limit analysis to masonry shells, in view of the presence of finite friction. Techniques for the form-finding of shells and for the optimisation of such forms, are then studied, and a finite-element technique developed for the finding of membrane thrust surfaces for shells incapable of carrying tension (as well as having possibly orthotropic properties). The technique is based on the solution of the partial differential equation relating shape, stress and loading, given a specific loading regime, and specific boundary conditions. The stress distribution, satisfying the given boundary and material conditions, is obtained, not on the basis of a trial-and-error approach, as is often the case, but on a plane stress analysis of the horizontal projection of the shell. The resultant shape hence automatically satisfies the boundary conditions. Various examples of the results of such method are given.

This study presents results from non-destructive testing to evaluate the degradation of the CFRP-masonry bond using thermal imaging. The goal of the research was to identify locations where there was evidence of bond deterioration that could subsequently be verified through destructive pull-off testing. Four full-scale masonry walls were built outdoors at the University of South Florida in 1995 to evaluate the effectiveness of CFRP for repairing settlement damage. Two of the settlement-damaged walls were repaired using single layer, commercially available unidirectional CFRP systems that used Tonen (wall 3) and Henkel (wall 2) epoxies. These two walls were the subject of this investigation. Before non-destructive tests were initiated, historical site data on temperature, humidity and rainfall variation was compiled. Over seventeen years, the walls experienced ambient temperatures as high as 98°F and as low as 25°F. The average rainfall in Tampa is about 34 inches and the annual average high humidity is around 87%#37;. Because of the high temperature and humidity, the CFRP-masonry bond was exposed to a particularly aggressive environment. Three types of thermal evaluation were carried out: thermocouple monitoring and both passive (solar) and active (localized heating) infrared thermal imaging. Twenty-four thermocouples were used to observe the spatial variations in temperature on the wall. Data showed that the surface temperatures of the wall are uneven with one end being hotter than the other. Measurements indicated that the wall temperatures went as high as 103°F during the week of data collection in late March and early April of 2012. In contrast, the highest ambient temperature over the same period was 92°F. The high temperature experienced by the wall is below the glass transition temperature for the epoxies, which ranges from 140°F to 180°F. A FLIR Tau 320 thermal imaging camera was used to identify localized de-bonding. Solar radiation heated the walls and the goal of thermal imaging was to detect hot spots which are indicative of de-bonding. Although this technique is ideal for exterior applications, initial attempts were unsuccessful. Once de-bonds were located by sounding, the camera was capable of confirming two hot spots on wall 2. A thermal scanner built by the university from a series of ten Omega OS137 thermal sensors was used to obtain more complete thermal images of the walls. This scanner had a heating element which supplied heat and allowed for active thermography. The scanner detected 16 hot spots not seen with the thermal camera. Ten of the twelve spots on wall 2 are concentrated on a region of the wall which experienced the highest daily changes in temperature, which indicates that higher thermal and environmental cycling has caused greater de-bond. Based on the number of hot spots found using both active and passive thermography the Tonen epoxy is performing better than the Henkel epoxy. In general, the bond has endured; however, there are a few localized areas that have de-bonded. Pull-off tests are recommended on walls 2 and 3. Five locations in regions suspected to have poor bond and five locations in regions suspected to have good bond are identified for each wall.