Masonry Elements Research Articles

The Stress-Strain State Computer Modelling of Reinforced Masonry Under Local Loading

Reinforced masonry elements stress-strain state modelling allows to define places in which stresses and strains are maximum. It is necessary to pay special attention to these places during experimental investigation. Accepted models of structures are adequate and corresponded to real constructions. Using computer modelling by the finite element method, the finite element size influence on the calculation accuracy is determined. The necessary resources of a personal computer to create and calculate such a model are sufficient and suitable for studying modelled structures stress-strain state. Good convergence of the deformations obtained from the resistive-strain sensors during the experimental investigations and according to the numerical modelling results is received.

Structural performance of unreinforced masonry elements made with concrete and horizontally perforated ceramic blocks – Laboratory tests

This paper discusses masonry buildings constructed in Pernambuco and their relationship to several failures that have occurred, some of which included the death of inhabitants. Topics such as the main features of this building technique and its peculiarities that played an important role in its structural behaviour are discussed in detail. Additionally, the paper presents a large characterization of materials and components used constituting the most important current research on this topic in Brazil. Its content analyses in depth, experimentally, the behaviour of single bricks, prisms and wallets that allow the identification and quantification of the influence of several mortar rendering layers on the load capacity of elements tested. A critical analysis concerning the factors that contribute to the performance observed is presented from which it was possible to realize a significant variability of results. A summary with the main results of all experimental tests is presented.

Numerical evaluation of seismic-induced damages in masonry elements of historical arch viaduct

The main purpose of this research was to estimate the seismic response of the historical masonry arch viaduct located in Krakow (Southern Poland) subjected to the representative strong seismic event. For the numerical evaluation a 3D finite element model (FEM) of the masonry viaduct was assembling with the ABAQUS/Standard software program. To represent nonlinear behaviour of the masonry structural elements of the viaduct under the strong seismic event, a Barcelona Model (BM) was assumed as a constitutive material model. Three components of the registered strong seismic shock were applied as kinematic excitation acting in three directions. The results of the numerical simulation showed that evident nonlinear behaviour of the masonry structural elements of the viaduct was observed under the earthquake. The plastic strains as well as the tensile damage (cracking) were obtained in some zones of the walls of the structure after seismic shock. On the basis of the obtained results authors also discussed the methodology for structural health monitoring (SHM) as well as seismic retrofitting which could be dedicated for historical masonry arch viaducts and bridges.

Mineralogical, petrographic and physical-mechanical study of Roman construction materials from the Maritime Theatre of Hadrian's Villa (Rome, Italy)

This paper presents the study of various Roman materials used in the construction of the Maritime Theatre, one of the main buildings in the Hadrian’s Villa complex, a designated UNESCO World Heritage Site located in Tivoli (Rome, Italy), dating to the first half of the II century A.D. The plaster layers (arriccio and intonachino) and overlying original Roman paintings that form the concave wall of the portico as well as some bedding mortars of the pyramidal stone elements (i.e. cubilia) of the circular masonry have been studied in particular. In addition, the acid volcanic rocks of the cubilia have been investigated, aiming to understand their state of alteration and geological origin.By mineralogical-petrographic microscopy (OM), diffractometry (XRPD), Raman spectroscopy, Point Load Tests (PLT), helium pycnometry, and particle size analysis, the composition and granulometric distribution of the aggregate, type and characteristics of the binder, and various physical-mechanical properties (density, porosity, water absorption, imbibition and saturation indices, mechanical resistance) of mortars and stones were defined. In addition, through digital image analysis of thin sections, the binder/aggregate ratio and some geometric characteristics of the aggregates (e.g. circularity) were determined.The research aims to improve the knowledge of the constructive technologies of the Maritime Theatre through the analysis of its materials.

Use of natural fibrous plaster for improving the out of plane lateral resistance of mortarless interlocked masonry walling

Previous studies had shown that the addition of fibres to masonry elements, (i.e. blocks, mortar and plaster), improved their mechanical properties compressive, shear and tensile strength by factors of typically 0.50, 4.25 and 3.0 respectively. The use of natural fibres within plaster did more to enhance the wall strength than fibres within blocks or mortar. In this study, the effectiveness of natural fibrous plaster for improving the out of plane lateral resistance of mortarless interlocked masonry walling was evaluated. Using 1.5 m high columns, the comparisons of mechanical parameters (like elastic stiffness, first crack load, and toughness index) were carried out. Experimental work was concentrated on fibrous plasters. Non-plastered, plain-plastered and fibrous-plastered masonry columns were compared, using both sisal fibres and rice straw. The factor of increase in failure loads over unplastered columns was found to be up to 5 times for plain and up to 21 times for fibrous plastering.

Axial compression behaviour of reinforced wallettes fabricated using wood-wool cement panel

Wood-wool cement composite panel (WWCP) is one of wood based composite material that produced in a stable panel form and suitable to be used as building wall system to replace non-ecofriendly material such as brick and other masonry element. Heavy construction material such as brick requires more manpower and consume a lot of time to build the wall panel. WWCP is a lightweight material with a density range from 300 kg/m3 to 500 kg/m3 and also capable to support an imposed load from the building. This study reported on the axial compression behaviour of prefabricated reinforced wallettes constructed with wood-wool cement panel. A total of six specimens were fabricated using two layers of cross laminated WWCP bonded with normal mortar paste (Portland cement) at a mix ratio of 1:3 (cement : sand). As part of lifting mechanism, the wallettes were equipped with three steel reinforcement (T12) that embedded inside the core of wallettes. Three replicates of wallettes specimens with dimension 600 mm width and 600 mm length were fabricated without surface plaster and with 16 mm thickness of surface plaster. The wallettes were tested under axial compression load after 28 days of fabrication until failure. The result indicated that, the application of surface plaster significantly increases the loading capacity about 35 % and different orientation of the panels improve the bonding strength of the wall.

Static in-plane shear behaviour of prefabricated wood-wool panel wallettes

The green construction material and technique are the current issue toward improving sustainability in the construction industry in Malaysia. The use of construction material that produced from renewable resources is a part of the effort for greening this industry. WWCP (Wood-wool cement panel) is a wood based product available to the construction industry to be used as a structural building wall element. This renewable material has the potential to replace the less eco-friendly materials such as bricks and other masonry element. However, the behaviour of wall subjected to the different load conditions is not well established and therefore, this study aimed to investigate the structural behaviour of the small scale wall (wallettes) subjected to in-plane lateral load. As a comparison, two types of fabrication technique of wallettes with dimension of 1200 mm × 1200 mm (± 30 mm) were considered. The conventional vertical stacking technique was denoted as W1 and new propose techniques (cross laminated) was denoted as W2. Three replicates of each type were fabricated and tested under in-plane lateral load until failure. The test results revealed that, the wallettes fabricated using the new fabrication technique significantly increased two times in load carrying capacity compared to wallettes with conventional technique.

Deflection limitation of beam‐type reinforced masonry constructions – proposals for future requirements

AbstractDeflection limitation of reinforced masonry building elements under bending is undertaken according in DIN EN 1996‐1‐1:2013‐02, Section 5.5.2.6, Table 5.2 [N 4], by limiting the span l ef or the ratio of lef to the effective depth d, for example lef/d ≤ 20 for simply supported beams. A further requirement in DIN EN 1996‐1‐1:2013‐02, Section 7.3, states that reinforced masonry elements should not deflect excessively under serviceability loading conditions. For reinforced masonry with dimensions, which are within the limits stated in clause 5.5.2.6 [N 4], acceptable vertical deflection of a beam can normally be assumed.In this scientific paper, the figures stated in [N 4] for the limitation of the bending slenderness l ef/d of reinforced masonry beams like masonry or prefabricated lintels are checked by calculation with the ”ζ procedure“ from reinforced concrete theory. The suitability of this procedure was first demonstrated by comparing calculated and experimentally obtained values.It was determined that maintenance of the bending slenderness ratio lef/d ≤ 20 for the tested calcium silicate masonry lintels does not always lead to deflection values w/lef ≤ 1/250. For prefabricated straight (flat arch) calcium silicate lintels and horizontal aerated concrete lintels with limit slendernesses of lef/d ≤ 15 and calcium silicate masonry lintels with lef/d ≤ 10, w/lef ≤ 1/250 was fulfilled.With regard to future requirements for the tested reinforced masonry constructions, a method is proposed for the calculation of the limit slenderness ratio lef/d, which leads to maintenance of w/lef ≤ 1/250. Furthermore, the presented ”ζ procedure“ enables reliable calculation of deflection figures at the serviceability limit state considering long‐term effects.

Numerical Investigation of Masonry Strengthened with Composites.

In this work, two main fiber strengthening systems typically applied in masonry structures have been investigated: composites made of basalt and hemp fibers, coupled with inorganic matrix. Starting from the experimental results on composites, the out-of-plane behavior of the strengthened masonry was assessed according to several numerical analyses. In a first step, the ultimate behavior was assessed in terms of P (axial load)-M (bending moment) domain (i.e., failure surface), changing several mechanical parameters. In order to assess the ductility capacity of the strengthened masonry elements, the P-M domain was estimated starting from the bending moment-curvature diagrams. Key information about the impact of several mechanical parameters on both the capacity and the ductility was considered. Furthermore, the numerical analyses allow the assessment of the efficiency of the strengthening system, changing the main mechanical properties. Basalt fibers had lower efficiency when applied to weak masonry. In this case, the elastic properties of the masonry did not influence the structural behavior under a no tension assumption for the masonry. Conversely, their impact became non-negligible, especially for higher values of the compressive strength of the masonry. The stress-strain curve used to model the composite impacted the flexural strength. Natural fibers provided similar outcomes, but a first difference regards the higher mechanical compatibility of the strengthening system with the substrate. In this case, the ultimate condition is due to the failure mode of the composite. The stress-strain curves used to model the strengthening system are crucial in the ductility estimation of the strengthened masonry. However, the behavior of the composite strongly influences the curvature ductility in the case of higher compressive strength for masonry. The numerical results discussed in this paper provide the base to develop normalized capacity models able to provide important information on the out-of-plane behavior of masonry elements strengthened with inorganic matrix and several kinds of fibers, both synthetic and natural.

Experimental Determinations for the Massive Masonry Resistance of Patrimony Buildings Subjected to the Action of Environmental Factors and Mechanical Demands

The paper presents the results of the experimental determinations of the resistance of the massive masonry elements from a patrimony building in the Oltenia Region, the masonry under the action of the environmental factors and the strong seismic movements occurring during their lifetime. Starting from the models of massive masonry behavior specific to the analyzed building type, the short compressive strength of the masonry elements from the analyzed building was determined experimentally. All the researches undertaken bring valuable data needed to predict the collapse of massive masonry buildings in national and world heritage.

Design provisions for FRCM systems bonded to concrete and masonry elements

Abstract Fibre Reinforced Cementitious Matrix (FRCM) materials are becoming an alternative strengthening technique to the well-known Fibre Reinforced Polymer (FRP) materials applied by means of epoxy resin, especially for masonry elements. Experimental tests have shown that the performance of elements strengthened with FRCM systems depends on the bond behaviour at both the reinforcement/substrate and grout/grid interface. Because of the novelty of the FRCM technique and the wide spectrum of FRCM materials (both grouts and grids) present on the market, no design indications are now available for such a strengthening technique, for both concrete and masonry elements. In this paper, a critical analysis of the available literature on bond tests on masonry and concrete elements externally bonded with FRCM materials was done, firstly. Successively, the collected results were examined in terms of failure mode and maximum strain in order to identify the main geometric and mechanical properties of the reinforcement and the substrate influencing the performance of the strengthening technique. Regression analyses were, thus, carried out on the collected experimental results, separately for concrete and masonry elements, in order to asses reliable formulations predicting the maximum strain in function of the axial stiffness of the reinforcement, the mechanical properties of the substrate, and the experimentally observed failure modes. Basing on the average provisions of the maximum strain in the FRCM reinforcement, characteristic values were also assessed according to a ‘design by testing’ procedure.

Measures of the vibration function pass in the wall element diagnostic test

Building constructions as well as their constituent structural elements must meet the strength requirements, which will not jeopardize the safety of their use. As part of the research experiment, the focus was on the issue related to strength testing properties of masonry elements using a non-invasive test method involving the measurement of vibrations. 40 samples of bricks. Half of them were deliberately damaged so that it would be possible to assess the suitability of the measurement method used and its variability resulting from damage to the masonry element.

The influence of the moisture content in historical masonry walls on the load bearing capacity

The moisture content in historical masonry walls, particularly on the ground floor, caused by i.e. lack of damp insulation, is a phenomenon of common occurrence. It is usually analysed in terms of mycological changes, thermal insulation and frost damage. The paper discusses the influence of the increased moisture content on the weight and load bearing capacity of the structure. The determination of moisture content in masonry elements, performed during the inspection of the building, provides information from which an increase in the structure's weight can be defined. Reliable tests for the moisture content and compressive strength of masonry and mortar components are invasive, and the number of testing in historical buildings should be limited to the minimum necessary to preserve their vintage nature. As a result, the received overall picture of the work of masonry may not be consistent with its actual state since historical buildings could have been rebuilt or repaired, and consequently, contain masonry conversions made of various materials with different properties. Absorbability can serve here as an example as it is a factor that disrupts a reliable determination of load bearing capacity values of masonry structures. The article attempts to determine the change in load bearing capacity of a moist masonry structure compared to the original - in the air-dry state - for various types of historical masonry and mortar components. The main influence analysed was due to capillary action, whereas the effect of other sources of moisture, i.e. salinity, was excluded.

Nonlinear analysis of contemporary and historic masonry vaulted elements externally strengthened by FRP

This paper addresses numerical modeling and nonlinear analysis of unreinforced masonry walls and vaults externally strengthened using fiber reinforced polymers (FRP). The aim of the research is to provide a simple method for design of strengthening interventions for masonry arched structures while considering the nonlinear behavior. Several brick masonry walls and vaults externally strengthened by FRP which have been previously tested experimentally are modeled using finite elements. Numerical modeling and nonlinear analysis are performed using commercial software. Description of the modeling, material characterization and solution parameters are given. The obtained numerical results demonstrate that externally applied FRP strengthening increased the ultimate capacity of the walls and vaults and improved their failure mode. The numerical results are in good agreement with the experimentally obtained ultimate failure load, maximum displacement and crack pattern; which demonstrates the capability of the proposed modeling scheme to simulate efficiently the actual behavior of FRP-strengthened masonry elements. Application is made on a historic masonry dome and the numerical analysis managed to explain its structural behavior before and after strengthening. The modeling approach may thus be regarded a practical and valid tool for design of strengthening interventions for contemporary or historic unreinforced masonry elements using externally bonded FRP.

Structure and properties of masonry mortars based on ceramic microspheres

Modern requirements in the field of energy and resource saving determines the need to apply effective fencing structures. To ensure the thermal homogeneity of the structures erected with small-piece masonry elements (ceramic and light-weight concrete units etc.), it is necessary to use lightweight mortars. One of the most effective methods to obtain such mortars is the introduction of hollow ceramic microspheres as a filler into their composition. The purpose of this work is studying of the composition and structure of a cement masonry mortar with hollow ceramic microspheres and modifying additives in correlation with its properties. The methods of thermogravimetric analysis, scanning electron microscopy, X-ray diffraction and standard test methods for the masonry mortars were used. The effect of the structural characteristics of the composite on the properties of final product was analyzed. It is established that the microstructure of the modified mortar samples is more compact in compare with basic composition, and the surface of the microspheres is covered by the products of the chemical interaction of its walls with the cement matrix. The aforesaid research allowed to obtain the high-performance lightweight mortars with hollow ceramic microspheres.

Optimizing mortar extrusion using poplar wood sawdust for masonry building block

The wood industry generates some 12 million tons of waste in France, 60% of which basically stems from sawmills. The reuse of this waste in the most common construction materials (e.g., concrete) may offer a sustainable solution. In the literature, the optimization of composites formulations generally focuses on aggregates plant pretreatment regardless of classical optimization parameters and the implementation process that can afford to get a high strength composite. The work presented herein is intended to optimize the mix design of a mortar made from poplar wood by-products, without involving any pretreatment. The conventional mix design parameters (i.e., paste volume, W/C ratio) have been varied. An optimal implementation technique (i.e., extrusion) was used. The wood mortar mix designs have been optimized in order to obtain composites compliant with French standard NF EN 771-3/CN, with respect to criteria regarding both dimensional tolerance and mechanical strength for structural elements (i.e., above 8 MPa at 7 days).A mortar mix design, optimized by means of extrusion, has been used as a reference. Poplar wood particles have been introduced through substitution for the sand volume. Test results indicate that the blocks produced from two wood mortar mixes with 60 and 70% wood aggregate-for-sand substitution rates are in line with the normative requirements relative to dimensional tolerances and mechanical strength. This material compliance underscores the potential use of such blocks as load-bearing masonry elements, thus facilitating the building of structures with a limited environmental impact.

Non–Linear Analysis of Slender Masonry Beam

Abstract This paper deals with numerical analysis and design of slander prismatic masonry beams loaded predominantly by axial force and bending moment in plane of the principal moment of inertia. Because of the material non-linearity, classical mathematical theory of slender columns cannot be applied for masonry elements, therefore the proposed method uses iterative non–linear calculation considering both material and geometrical non–linearity.

Non-invasive estimation of moisture content in tuff bricks by GPR

Measuring water content in buildings of historical value requires non-invasive techniques to avoid the damage that sample taking or probe insertion may cause to the investigated walls. With this aim, a stepped frequency ground penetrating radar (GPR) system was tested to assess its applicability in moisture measurements of porous masonry elements. The technique was tested on a real scale wall made with yellow Neapolitan tuff bricks, a material commonly found in historical buildings of Campania (Southern Italy). First, the antenna was calibrated to find its characteristic transfer functions. Then 64 GPR acquisitions, coupled with gravimetric measurements of the volumetric water content, were performed on the tuff wall in laboratory controlled conditions. A full inverse modelling of the GPR signal on tuff was used to retrieve dielectric permittivity and electrical conductivity of tuff at various water contents. By linking these characteristic electromagnetic parameters to the water content, the calibration relationships specific for yellow Neapolitan tuff are defined, which can be used for moisture measurements by GPR in real case studies. The experimental results lead to a robust identification of clearly defined monotonic relationships for dielectric permittivity and electrical conductivity. These are characterized by high values of the correlation coefficient, indicating that both parameters are potentially good proxies for water content of tuff. The results indicate that GPR represents a promising indirect technique for reliable measurements of water content in tuff walls and, potentially, in other porous building materials.

Enlightening the use of materials and techniques in earthen architecture in southeast Brazil during the first coffee cycle (19th century)

Abstract The broad ensemble of fine rural and urban constructions erected during the first cycle of coffee production in Brazil (1820–1880) in the middle valley of the Paraiba do Sul River in southeast Brazil, is a legacy of earthen architecture of exceptional importance. A rare example of simultaneous presence of three different earthen architecture techniques (wattle-and-daub, adobe and rammed earth), this heritage faces threat of disappearance due to lack of public concern and loss of know-how directed to earthen techniques. In this paper, the physical and chemical analysis of a large set of samples of local soils and masonry elements formed the basis for a discussion on raw materials and techniques originally used in the construction of those buildings. The information gathered in this work is intended to contribute in the rescue of the immaterial heritage related to building practices in colonial and post-colonial Brazil and to support conservation and restoration actions.

Plane and vaulted masonry elements strengthened by different techniques – Testing, numerical modeling and nonlinear analysis

This paper presents numerical modeling and nonlinear analysis of unreinforced masonry walls and vaults externally strengthened by different techniques. The aim of the research is to provide a simple and reliable calculation method to enable the design and structural evaluation of strengthening measures for masonry plane and arched structures. Numerical modeling by finite elements and nonlinear analysis are carried out using commercial software ANSYS12.0. In order to validate the adopted approach, an experimental program was conducted where unreinforced brick masonry walls and vaults were strengthened by several techniques and loaded until failure. Comparison of experimental and numerical results showed acceptable agreement. Furthermore, a parametric study is conducted to investigate and compare several strengthening configurations for unreinforced masonry vault in order to select the optimum solution. The numerical results are discussed and the deduced conclusions illustrate the applicability of the proposed approach as a practical and valid tool for design of strengthening interventions for contemporary or historic masonry elements and assemblages.