The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Paulo B Lourenco - One of the best experts on this subject based on the ideXlab platform.
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experimental bond behavior of frp sheets glued on brick Masonry
Journal of Composites for Construction, 2011Co-Authors: Daniel V Oliveira, Ismael Basilio, Paulo B LourencoAbstract:This paper deals with the experimental characterization of the mechanical tensile and shear bond behavior of fiber-reinforced polymer (FRP) sheets externally glued on Masonry prisms, in terms of load capacity and stress distribution along the bonded length. The brick Masonry adopted tries to replicate ancient brick Masonry, by using handmade low-strength solids bricks and low-strength lime-based mortar. Key parameters relative to the FRP-Masonry interface response, particularly bonded length, FRP materials, anchor scheme adopted, and shape of Masonry substrate, were studied. Finally, an analytical bond stress-slip formulation was developed, allowing deducing local bond stress-slip curves directly from the experiments.
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experimental characterization of stone Masonry in shear and compression
Construction and Building Materials, 2009Co-Authors: Graca Vasconcelos, Paulo B LourencoAbstract:Abstract Shear and compressive mechanical properties are needed for the evaluation of the strength of Masonry shear walls by means of simplified methods or numerical analysis. This, in turn, allows to design or assess Masonry buildings subjected to combined vertical and horizontal loading. Even if many results on the mechanical properties of modern brick and block Masonry are available in the literature, only a few results exist for stone Masonry. Here, the shear and compressive strength parameters of stone Masonry using granite blocks are provided. In addition, a first aspect addressed is the shape of the shear stress–displacement diagrams under monotonic and cyclic loading. A second aspect addressed is the influence of the surface roughness and of the bed joint material on the compressive behavior of Masonry.
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finite element modelling of deformation characteristics of historical stone Masonry shear walls
Engineering Structures, 2009Co-Authors: Ramakrishnan Senthivel, Paulo B LourencoAbstract:Abstract Two dimensional nonlinear finite element analysis based on experimental test data has been carried out to model deformation characteristics, such as load–displacement envelope diagrams and failure modes of historical stone Masonry shear walls subjected to combined axial compression and lateral shear loading. An experimental research work was carried out on three different types of historical stone Masonry shear walls that can be considered representative of ancient stone Masonry constructions. Those three types of Masonry are: (i) sawn dry-stack or dry-stone Masonry without bonding mortar, (ii) irregular stone Masonry with bonding mortar, and (iii) rubble Masonry with irregular bonding mortar thickness. Plasticity theory based micro modelling techniques has been used to carry out the analysis. The stone units were modelled using eight node continuum plane stress elements with full Gauss integration. The joints and unit-joint interfaces were modelled using a six node zero thickness line interface elements with Lobatto integration. This paper outlines the experimental research work, details of numerical modelling carried out and report the numerical lateral load–displacement diagrams and failure modes. The numerical analysis results were compared with the experimental test results and good agreement was found.
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mechanics of hollow concrete block Masonry prisms under compression review and prospects
Cement & Concrete Composites, 2007Co-Authors: Gihad Mohamad, Paulo B Lourenco, Humberto R RomanAbstract:Abstract The aim of this work is to critically assess the mechanical properties of hollow concrete Masonry using experimental results from prisms constructed with blocks of two different strengths and four types of mortar. A key conclusion is that mortar is mostly responsible for the non-linear behavior of Masonry. Moreover, a strongly non-linear relationship between Masonry elasticity modulus and compressive strength is found, which contradicts the simple linear relation proposed by Eurocode 6 [CEN. Eurocode 6: Design of Masonry structures – Part 1 – Common rules for reinforced and unreinforced Masonry structures. EN-1996-1-1; 2005.]. The porosity of mortar and the state of stress that mortar undergoes in the process of compressive loading can be responsible for changes in the mechanical properties, such as elasticity modulus and Poisson’s ratio. Finally, different types of mortars induce different failure modes in the Masonry prisms and there is clear evidence that the failure of hollow concrete Masonry starts after onset of mortar crushing. In order to better reproduce the observed experimental behavior, a tentative model for the mortar Poisson’s ratio variation upon loading is also presented.
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Masonry shear walls subjected to cyclic loading influence of confinement and horizontal reinforcement
2007Co-Authors: Joao Gouveia, Paulo B LourencoAbstract:The behavior of Masonry shear walls is fundamental in the design of Masonry buildings subjected to different actions, namely of seismic nature. The usage of unreinforced, confined or reinforced Masonry is currently subjected to a strong debate in Europe due to the new codes. In particular, the part of Eurocode 8 (Design of structures for earthquake resistance) related to Masonry structures is only a limited compromise for the different countries. A large testing program was started at University of Minho in order to clarify issues regarding confined Masonry and unfilled vertical joints. Confined Masonry is assumed as a hybrid material joining Masonry with small section horizontal and vertical lightly reinforced concrete elements. This project, partly sponsored by the light-weight concrete block industry, aims at defining adequate structural solutions for regions of low to high seismicity in Portugal. This paper discusses the results of the experimental program, consisting mainly of Masonry walls subjected to cyclic actions and constant pre-compression. Sixteen specimens are considered, being the shear strength, ductility, energy dissipation and stiffness discussed. The key aspects under discussion are: (a) the possibility of replacing the filling of the vertical joints by interlocking and horizontal bed joint reinforcement, (b) the need for filling vertical joints in confined Masonry solutions. 1 PhD Student, Department of Civil Engineering, University of Minho, jopamago@isec.pt 2 Associate Professor, Department of Civil Engineering, University of Minho, pbl@civil.uminho.pt Papers contained in these Proceedings have been reviewed in accordance with the policies of The Masonry Society
Jason Ingham - One of the best experts on this subject based on the ideXlab platform.
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experimental study on scale effects in clay brick Masonry prisms and wall panels investigating compression and shear related properties
Construction and Building Materials, 2018Co-Authors: Charlotte Knox, Dmytro Dizhur, Jason InghamAbstract:Abstract Scaled Masonry model testing has been performed for many decades, with earlier researchers establishing that it is possible to model Masonry behaviour at reduced scale, but that strength and stiffness are affected and with many studies suggesting that Masonry is anisotropic. The effects of scale on clay brick Masonry compressive strength, Young’s Modulus, shear modulus and diagonal tensile strength was investigated through material and component testing at two scales. Firstly, the effect of scaling the brick and mortar joints to half scale was assessed, and secondly, the effect of scaling the size of the specimen without scaling the brick and mortar size was assessed. Scale was found to have minimal to no effect in both test cases on the compressive strength characteristics of Masonry and brick, and to have no effect on the stiffness of Masonry in compression. The effects of scale were found to be significant for diagonal shear strength and shear modulus.
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compressive flexural bond and shear bond strengths of in situ new zealand unreinforced clay brick Masonry constructed using lime mortar between the 1880s and 1940s
Journal of Materials in Civil Engineering, 2014Co-Authors: Ronald Lumantarna, David T. Biggs, Jason InghamAbstract:AbstractThe importance of sufficient Masonry mortar joint-bond strength when a structure is subjected to in-plane and out-of-plane loads has been emphasized by several researchers. However, Masonry unit/mortar bond strength is difficult to predict, and performing mechanical tests on existing Masonry buildings to determine Masonry flexural bond and shear bond strengths is generally not practical, such that predictive expressions relating the Masonry flexural bond and shear bond strengths to other Masonry properties are desirable. Although relationships between brick/mortar bond and compressive strength have been investigated previously by researchers located in many different parts of the world, most of these studies were laboratory-based and did not include testing of existing Masonry buildings within their scope. The writers aimed to characterize the material properties of New Zealand unreinforced clay brick Masonry (URM) buildings that were generally built between 1880 and 1930, with in situ testing and...
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uniaxial compressive strength and stiffness of field extracted and laboratory constructed Masonry prisms
Journal of Materials in Civil Engineering, 2014Co-Authors: Ronald Lumantarna, David T. Biggs, Jason InghamAbstract:AbstractMasonry material characteristics such as compression stress-strain behavior and the relationships between brick, mortar, and Masonry compressive strengths are required for the detailed analysis and assessment of Masonry structures. These properties have been investigated previously, but most past studies were laboratory based and did not include within their scope the testing of existing Masonry buildings. This study aimed to characterize the compressive strength and the compression stress-strain relationship of vintage clay brick Masonry used in New Zealand unreinforced Masonry (URM)-bearing wall buildings that were generally constructed between 1880 and 1940. Testing was performed on 45 Masonry prisms that were extracted from eight New Zealand historic URM buildings and on 75 Masonry prisms that were constructed in the laboratory using 14 different brick/mortar combinations. It was found that the laboratory-constructed sample test results adequately replicated those from the field-extracted samp...
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debonding resistance of frp to clay brick Masonry joints
Engineering Structures, 2012Co-Authors: J Kashyap, Jason Ingham, C Willis, M C Griffith, Mark J MasiaAbstract:Abstract Debonding at the FRP-to-Masonry interface has been identified as the preferred failure mechanism in fibre-reinforced polymer (FRP) retrofitted Masonry as it allows for some redistribution of forces. The results of 14 FRP-to-Masonry bond tests are presented, where the FRP was near surface mounted (NSM) to stack-bonded clay brick Masonry. These tests were conducted to investigate the effect that variables such as cyclic loading and FRP strip dimensions have on the debonding resistance of a NSM FRP-to-Masonry joint. These results were then incorporated into a large database of FRP retrofitted Masonry pull test results by various researchers over the past 10 years. The database includes results for both externally bonded (EB) and NSM retrofitting techniques. From this database, local bond–slip parameters such as the maximum interface shear stress, τmax, and the maximum slip, δmax, were investigated to determine correlations between these values and Masonry material properties. Further, 15 existing concrete and Masonry bond strength (maximum load at the FRP-to-substrate interface) models in the literature were assessed for their use with Masonry by comparing these models against the results in the pull test database. Based on the comparative statistics of the test-to-predicted bond strength it is concluded that a new FRP-to-Masonry bond model is required which gives more accurate predictions. Results include a discussion on the global load–slip response and FRP-to-Masonry interface behaviour.
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design expression for the in plane shear strength of reinforced concrete Masonry
Journal of Structural Engineering-asce, 2007Co-Authors: Kok Voon, Jason InghamAbstract:Aspects relating to codification of the in-plane shear strength of concrete Masonry walls when subjected to seismic loading are presented in this paper. Particular emphasis is placed on a model that is capable of representing the interaction between flexural ductility and Masonry shear strength to account for the reduction in shear strength as ductility level increases. The simple method proposed here allows the strength enhancement provided by axial compression load to be separated from the Masonry component of shear strength and is considered to result from strut action. In addition, minor modifications are made to facilitate adoption of the method in the updated version of the New Zealand Masonry design standard, NZS 4230:2004. Prediction of shear strength from NZS 4230:2004 and alternative methods are compared with results from a wide range of Masonry walls tests failing in shear. It was established that the shear equation in the former version of the New Zealand Masonry standard (NZS 4230:1990) was overly conservative in its prediction of Masonry shear strength. The current National Earthquake Hazards Reduction Program (NEHRP) shear expression was found to be commendable, but it does not address Masonry shear strength within plastic hinge regions, therefore limiting its use when designing Masonry structures in seismic regions. Finally, the new shear equation implemented in NZS 4230:2004 was found to provide significantly improved shear strength prediction with respect to its predecessor, with accuracy close to that resulted from NEHRP.
B Venkatarama V Reddy - One of the best experts on this subject based on the ideXlab platform.
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mortar shrinkage and flexure bond strength of stabilized soil brick Masonry
Journal of Materials in Civil Engineering, 2018Co-Authors: B Venkatarama V Reddy, M S LathaAbstract:AbstractThe bond development between the Masonry materials is influenced by the characteristics of the Masonry unit and the mortar. The mortar, sandwiched between the Masonry units, undergoes shrin...
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prediction of solid block Masonry prism compressive strength using fe model
Materials and Structures, 2010Co-Authors: Ch Uday V Vyas, B Venkatarama V ReddyAbstract:Masonry strength is dependent upon characteristics of the Masonry unit, the mortar and the bond between them. Empirical formulae as well as analytical and finite element (FE) models have been developed to predict structural behaviour of Masonry. This paper is focused on developing a three dimensional non-linear FE model based on micro-modelling approach to predict Masonry prism compressive strength and crack pattern. The proposed FE model uses multi-linear stress–strain relationships to model the non-linear behaviour of solid Masonry unit and the mortar. Willam–Warnke’s five parameter failure theory developed for modelling the tri-axial behaviour of concrete has been adopted to model the failure of Masonry materials. The post failure regime has been modelled by applying orthotropic constitutive equations based on the smeared crack approach. Compressive strength of the Masonry prism predicted by the proposed FE model has been compared with experimental values as well as the values predicted by other failure theories and Eurocode formula. The crack pattern predicted by the FE model shows vertical splitting cracks in the prism. The FE model predicts the ultimate failure compressive stress close to 85% of the mean experimental compressive strength value.
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influence of sand grading on the characteristics of mortars and soil cement block Masonry
Construction and Building Materials, 2008Co-Authors: B Venkatarama V Reddy, Ajay GuptaAbstract:Sand constitutes bulk of the mortar volume. Sand grading can influence the characteristics of mortar and Masonry. Influence of sand grading on the characteristics of two types of mortars and soil–cement block Masonry are examined in this paper. Three different sand gradings were used to examine the workability, strength, water retentivity, drying shrinkage and stress–strain characteristics of cement mortar and cement–lime mortar. Bond strength, compressive strength and stress–strain characteristics of soil–cement block Masonry were also examined using these mortars. Major findings of the study are: (a) for a given consistency mortar with fine sand requires 25–30% more water, (b) as the sand becomes fine mortar compressive strength and modulus decreases while drying shrinkage increases, (c) fine sand reduces the tensile bond strength of Masonry, whereas Masonry compressive strength is not sensitive to sand grading variations and (d) Masonry modulus reduces as the sand used in the mortar becomes finer.
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influence of shear bond strength on compressive strength and stress strain characteristics of Masonry
Materials and Structures, 2008Co-Authors: B Venkatarama V Reddy, Ch Uday V VyasAbstract:The paper is focused on shear bond strength–Masonry compressive strength relationships and the influence of bond strength on stress–strain characteristics of Masonry using soil–cement blocks and cement–lime mortar. Methods of enhancing shear bond strength of Masonry couplets without altering the strength and modulus of Masonry unit and the mortar are discussed in detail. Application of surface coatings and manipulation of surface texture of the Masonry unit resulted in 3–4 times increase in shear bond strength. After adopting various bond enhancing techniques Masonry prism strength and stress–strain relations were obtained for the three cases of Masonry unit modulus to mortar modulus ratio of one, less than one and greater than one. Major conclusions of this extensive experimental study are: (1) when the Masonry unit modulus is less than that of the mortar, Masonry compressive strength increases as the bond strength increases and the relationship between Masonry compressive strength and the bond strength is linear and (2) shear bond strength influences modulus of Masonry depending upon relative stiffness of the Masonry unit and mortar.
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strength and elastic properties of stabilized mud block Masonry using cement soil mortars
Journal of Materials in Civil Engineering, 2006Co-Authors: B Venkatarama V ReddyAbstract:Stabilized mud blocks (SMBs) are manufactured by compacting a wetted mixture of soil, sand, and stabilizer in a machine into a high-density block. Such blocks are used for the construction of load-bearing Masonry. Cement soil mortar is commonly used for SMB Masonry. This paper presents the results of an experimental investigation in characterizing the properties of SMB Masonry using cement-soil mortars. The compressive strength, stress-strain relationships, and elastic properties of SMB Masonry using three types of SMBs and cement-soil mortars are discussed. The influence of a cement-soil mortar's composition and strength on Masonry characteristics is examined. The results of Masonry using cement-soil mortars are compared with those using conventional mortars (cement mortar and cement-lime mortar). Some of the major findings are: (1) SMB Masonry strength is sensitive to block strength and increases with increase in block strength; (2) the strength of SMB Masonry using cement-soil mortars is more sensitive to the cement content of the mortar than to the clay fraction of the mortar mix; (3) the Masonry modulus increases as the block strength increases; and (4) SMB Masonry with cement-soil mortars shows higher modulus than the Masonry using cement mortar and cement-lime mortar.
Pankaj Munjal - One of the best experts on this subject based on the ideXlab platform.
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bond strength and compressive stress strain characteristics of brick Masonry
Journal of building engineering, 2017Co-Authors: S B Singh, Pankaj MunjalAbstract:Abstract In this study, Masonry and its material characteristics such as compressive strength of Masonry prisms, bricks, mortars as well as bond strength (i.e., flexural and shear bond strengths) of brick and mortar joint are determined experimentally. The compressive stress-strain curves of brick, mortar, and Masonry have been plotted and five control points have been identified on the stress-strain curve of Masonry. The control points on the stress-strain curve would be useful for performance based design of Masonry. Four types of bricks and three different types of mortars have been used in the experimental study. The compressive strength of Masonry and flexural bond strength are determined with a test on five bricks stack bonded prisms. A bond wrench apparatus fabricated as per ASTM standards was used for flexural bond strength test. The shear bond strength of Masonry is predicted using Masonry triplet. It is observed that the concrete bricks have low flexural as well as shear bond strengths due to less contact area.
Humberto R Roman - One of the best experts on this subject based on the ideXlab platform.
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mechanics of hollow concrete block Masonry prisms under compression review and prospects
Cement & Concrete Composites, 2007Co-Authors: Gihad Mohamad, Paulo B Lourenco, Humberto R RomanAbstract:Abstract The aim of this work is to critically assess the mechanical properties of hollow concrete Masonry using experimental results from prisms constructed with blocks of two different strengths and four types of mortar. A key conclusion is that mortar is mostly responsible for the non-linear behavior of Masonry. Moreover, a strongly non-linear relationship between Masonry elasticity modulus and compressive strength is found, which contradicts the simple linear relation proposed by Eurocode 6 [CEN. Eurocode 6: Design of Masonry structures – Part 1 – Common rules for reinforced and unreinforced Masonry structures. EN-1996-1-1; 2005.]. The porosity of mortar and the state of stress that mortar undergoes in the process of compressive loading can be responsible for changes in the mechanical properties, such as elasticity modulus and Poisson’s ratio. Finally, different types of mortars induce different failure modes in the Masonry prisms and there is clear evidence that the failure of hollow concrete Masonry starts after onset of mortar crushing. In order to better reproduce the observed experimental behavior, a tentative model for the mortar Poisson’s ratio variation upon loading is also presented.
