Strength Of Masonry Research Articles

Influence of Loading Direction on Compressive Strength of Concrete Block Masonry

Influence of Loading Direction on Compressive Strength of Concrete Block Masonry

Fast Limit Analysis of Domes Belonging to the Architectural Heritage Under Different Hypotheses on Masonry Strength

ABSTRACT The load-bearing capacity of selected case studies of domes belonging to the architectural heritage is evaluated by means of two different semi-analytical approaches framed in the context of limit analysis. The first method is a static approach known as the “Durand-Claye method” or “stability area method”, and the second is a kinematic approach that combines the virtual power principle with the upper bound theorem of limit analysis. The fundamentals of these two methods were presented in previous works by the authors, under different hypotheses about the strength of masonry. Building on this theoretical background, the current study introduces novel analytical solutions for domes of varying shapes, specifically ogival domes and segmental domes with non-uniform thickness. These solutions are applied to real case studies of significant architectural importance: the ogival dome of the Church of Anime Sante in L’Aquila (Italy); the ogival dome of Escuelas Pías in Valencia (Spain), and the main segmental dome of the Global Vipassana Pagoda in Mumbai (India). The varying sizes of the examined domes allow for an analysis of the impact of limited tensile and compressive strength on collapse behavior, by comparing the results obtained through the static and kinematic methods with those derived from Heyman’s simplified assumptions.

EXPERIMENTAL STUDY ON COMPRESSIVE STRENGTH AND SHEAR STRENGTH OF MASONRY UNIT WITH FIBER GLASS AND POLYPROPYLENE FIBER PAINT COATING

In this study, the effects of fiber layers on the compressive and shear strength properties of masonry are investigated. The aim is to improve the mechanical properties of masonry walls that are prone to earthquakes The experimental investigations provide information on the mechanical properties of Indonesian masonry blocks under two conditions: without and with fiber coating. Two different types of fibers were used in this study: Fibreglass and Polypropylene fiber. The fiber content is 8% for 1 kg of paint with 5% water. The thickness of the coating applied to the masonry ranges from 1 mm to 3 mm. The compressive strength of the samples with a layer of polypropylene fibers with a thickness of 1 mm and 3 mm is 30.32 kg/cm², 31.16 kg/cm² and 47.16 kg/cm², respectively. The compressive strength of the samples with a layer of glass fiber paint with a thickness of 1 mm, 2 mm, and 3 mm is 30.1 kg/cm², 31.22 kg/cm², 53.31 kg/cm² and the value of the control sample is 25.89 kg/cm². The shear strength of masonry with polypropylene-coated fiber with a layer thickness of 1 mm, 2 mm, and 3 mm is 3.93 kg/cm², 4.64 kg/cm², and 5.89 kg/cm². The bricks reinforced with glass fiber paint with a layer thickness of 1 mm, 2 mm, and 3 mm have 3.77 kg/cm², 5.31 kg/cm², and 5.05 kg/cm².

The effects of brick wall and RC tie variables on the seismic performance of low-rise confined masonry buildings

An extensive parametric investigation is carried out to determine the effects of different RC tie system and brick wall variables on the performance of confined masonry walls and buildings. The variables considered include: the number of storeys and adjacent walls, the walls aspect ratio, thickness and compressive strength of masonry walls, presence of openings, the RC tie system dimensions, compressive strength and detailing of the longitudinal and transverse reinforcements. The main aim of the investigation is to verify the efficiency of some of the prescriptive code recommendations and to provide a basis for further descriptive guidelines for low-rise confined masonry buildings. Among the major conclusions, it is found that the main affecting parameters are those of the masonry walls themselves. When the walls have sufficient shear capacities, due to lower aspect ratio, higher compressive strength and wall thickness and lack of, or small openings, the flexural demand on the tie system is small and its elements act mainly as axially-loaded tie elements. Therefore, the least affecting parameters are those of the tie system's reinforcement detailing. However, when the masonry walls are weak in shear (low masonry strength and large openings), the demand on the tie system increases, to the point that instead of acting as an integral part of the wall, it acts similar to a weak, moment-resisting frame having infill masonry walls, for which it has not been designed. The scenarios that this will happen include: the wall aspect ratios AR > 2, the masonry compressive strength, f′m < 5.0 MPa and the ratio of length of opening to the length of the wall, Ol/Wl > 0.5. To avoid such behaviour, it is also suggested that the tensile stresses in the longitudinal bars of the RC tie elements be limited to 0.6fy.

Reliable unit strength correlations to predict the compressive strength of grouted concrete masonry

Compressive strength of grouted concrete masonry is an important parameter to design reinforced/grouted concrete masonry walls. The design standards stipulate two methods to determine the compressive strength of masonry (1) using tabulated unit strength and mortar type, and (2) testing representative masonry prisms. The compressive strength prediction of grouted concrete masonry is influenced by compressive strength values of hollow blocks, mortar and grout, and their geometries. Therefore, a multi-level approach was employed in this study to improve the existing unit strength correlations of the standards for more reliable prediction of compressive strengths of grouted concrete masonry. The existing methods to determine the compressive strength of grouted masonry were critically appraised and a database of compression tests of grouted concrete masonry prisms/wallettes was developed. This database was then used to evaluate the correlations between the compressive strengths of block, mortar, grout and masonry. The applicability of existing unit strength correlations from the design standards and literature were assessed and their relevancy and limitations are highlighted. Subsequently, updated sets of unit strength correlations are proposed in this study, through statistical reliability analyses of the predictions against the experimental results included in the database. The proposed unit strength correlations were classified according to the mortar type/strengths (≤ 10 MPa and > 10 MPa). It has been shown that the new correlations are more structurally reliable than the existing unit strength correlations through comparing the 95th percentile error values.

Development of predictive model for compressive strength of eco-brick masonry walls using numerical method

The usage of waste plastics in the form of eco-bricks for the construction of buildings is gradually gaining traction. However, the performance of eco-brick masonry walls is not sufficiently known, and the process of setting up experimental rigs for the conduct of compressive strength test of masonry are usually cumbersome and expensive. This study investigated the compressive strength performance of eco-brick masonry walls and developed a predictive model for evaluating the strength of eco-brick masonry walls. Waste polyethylene terephthalate (PET) bottles were physically recycled and utilised to manufacture four samples of eco-bricks, strength grades 40.5, 21.02, 13.52 and 3.05 N/mm2 using stone dust, sharp sand and laterite at predetermined moisture contents. The eco-bricks were laid with seven grades of mortar to build 54 eco-brick masonry prisms. A quasi-static compressive loading test was carried out on the masonries, and predictive models were developed using multiple non-linear regression. The study found that eco-brick masonry prisms supported large loads and failed due to the propagation of tensile cracks and debonding of the units. The study also found that the compressive strength of eco-brick masonry is a power function of the compressive strength of eco-bricks and the mortar used for the bonding. It was determined that the mean ratio of the expected to experimental prism strength was 1.002. The mathematical model developed in this study for predicting the strength of eco-brick masonries can significantly evaluate the compressive strength of eco-brick masonry.

Damage to monumental masonry buildings in Hatay and Osmaniye following the 2023 Turkey earthquake sequence: The role of wall geometry, construction quality, and material properties

Damage to monumental masonry buildings in Hatay and Osmaniye following the 2023 Turkey earthquake sequence: The role of wall geometry, construction quality, and material properties

Preliminary evaluation of predictions from compressive strength models for masonry

Compressive strength is the most essential design parameter of load-bearing masonry structures. The performance of masonry under compression depends on numerous parameters and is linked to the properties of its component materials, which enclose high variability, and to its geometrical characteristics and interlocking arrangement. Available predictive models are usually based only on few variables and therefore their estimates are liable to uncertainties. In this paper, the performance of four existing models for the estimation of the compressive strength of masonry made of solid units, is evaluated. To this end, experimental data from tests on single-layered specimens made of solid clay bricks, and subjected to monotonic compression, were collected from the literature. The predictions of the four models are compared to the experimental strength of the masonry specimens. The performance of each model is assessed through statistical analysis indices. From the analysis, it is concluded that the examined predictive models overestimate the masonry specimens with experimental strength less than 5 MPa.

Properties of ultra lightweight foamed concrete utilizing agro waste ashes as an alkaline activated material

In the present investigation, rice husk ash (RHA), bamboo leaf ash (BLA) and palm oil fuel ash (POFA) known as agricultural-waste materials locally available were used to produce ultra lightweight foamed concretes (ULFCs). BLA, RHA, and POFA were used as replacements for cement in ULFCs at different weight percentages of 0 %, 5 %, 10 %, 15 %, and 20 %. To achieve the target density of 350 kg/m3, cement was substituted with agricultural wastes, and a protein foaming agent was added. The properties of ULFCs were examined including, slump test, setting time, fresh density, splitting tensile, compressive and flexural strengths, thermal insulating, microstructural and transport properties, permeability and pore's structure. The experimental results demonstrated that BLA and POFA ashes significantly outperforms in terms of efficiency and improved the mechanical and transport qualities of ULFCs than RHA ash. By increasing the weight fractions of BLA, RHA, and POFA from 5 % to 20 % in ULFC mixes resulted in an improvement in slump, porosity, capillary sorption, water absorption, bulk density, intrinsic air permeability, and specific heat. The ideal results were seen in terms of compressive strength, bending strength, splitting tensile strength, and UPV when 15 % POFA and BLA, and 10 % RHA were used as substitutes for cement. The increase in weight fraction of BLA, RHA, and POFA resulted in a rise in both thermal conductivity and thermal diffusivity of ULFCs. SEM studies revealed that incorporating different agricultural wastes positively affects the pore size distribution within the microstructure decreasing with increased content of ashes related to the development of ULFCs with stronger matrix. As a result, the formulated ULFCs met the masonry strength criteria while also providing economic and environmental benefits.

ESTABLISHING THE RELIABILITY LEVEL OF MASONRY BEARING STRUCTURES BASED ON ITS COMPONENT STRENGTH ANALYSIS

The article discusses aspects related to assessing the reliability of masonry structures. The authors present methods for determining the compressive strength of masonry in existing structures, taking into account reliability theory. We also consider practical solutions for calculating the design strength of masonry, which may help to assess the safety of massive brick walls and pillars that act as core structural elements of existing buildings. Thus, walls and pillars operating in compression are vital elements of stone buildings and require special attention when analysing and assessing their strength. They carry enormous loads and are critical to the stability of the entire structure. There are cases when it may be hard to obtain safe samples for testing masonry mechanical performance, making the analysis of existing masonry structures difficult. However, building codes and methods provide specific methods for determining the strength of existing structures based on reliability theory. These methods assume uniformity of masonry with regularly spaced brick layers. Although such assumptions may simplify the analysis, they can still provide sufficiently accurate results for making decisions about the safety and reliability of the building. It is essential to consider all possible factors and limitations when using these methods to ensure a reliable assessment of the condition of masonry structures. Stone materials are among the most traditional in various areas of construction production. Buildings with brick load-bearing walls represent the lion’s share of the existing housing development in Ukraine. Ensuring its high-quality operation and the safety of residents during the life cycle of such buildings are priority areas. However, changes occurring in the external environment and the state of regulatory support for construction production require a periodic return to the issues of assessing the load-bearing capacity of both previously erected building structures and those under design. Thus, lately, the territories with previously unusual force impacts on building structures, such as horizontal displacements of the base of the building, have significantly expanded. The reasons for this include seismic activity in certain regions of the country and the results of anthropogenic factors, particularly the areas with unstable soils. We should note that many buildings and structures are subject to external influence due to military operations on a large territory of Ukraine. So, in the event of a hit by warheads or the action of a blast wave, they generate new, non-typical, but dangerous effects on the load-bearing structures of the entire building. Keywords: reliability theory, reliability assessment, structural safety, stone structures, masonry strength.

An Empirical Formula for Assessing the Characteristic Strength of Unreinforced Laterite Stone Masonry

This study aims to determine the needed coefficients for evaluating the uniaxial compressive strength characteristic value for masonry structures made of Laterite Stone (LS) and cement mortar, resulting from experiments conducted in the laboratory evaluating the compressive strengths of the laterite stone and mortar separately in masonry. It proposes calculation coefficients for the completion of Eurocode 6 data that fit the behavior of laterite stone-based masonry. The laterite stone blocks are extracted from three quarries in southern Burkina Faso. The dimensions of the masonry samples tested are 800 mm × 800 mm × 135 mm (±5 mm) with a cement mortar joint of 20 mm (±5 mm) thick. The different failure modes of masonry were also explored. The tests carried out on the masonry showed that the failure is initiated by vertical cracks through the block-mortar interface at a quarter of the width of the walls, generally at 40 to 60% of their maximum strength. The statistical analysis made through a linear regression from the standard model of approximation of the characteristic strength of masonry in Eurocode 6 was used to set out parameters for the empirical relation. The proposed formula considers the intrinsic properties of the block and the mortar, the thickness of the mortar, the dimensions of the masonry block, and the geometry of the masonry itself to evaluate its compression strength. The adequacy between the model and the experimental values is evaluated through the coefficient of determination and the standard error of 0.94 and 0.041 MPa, respectively. Doi: 10.28991/CEJ-2024-010-04-07 Full Text: PDF

INVESTIGATION OF DEFECTS IN DECORATIVE BRICK CLADDING OF FACADES OF FRAME BUILDINGS

The use of layered walls in the construction of frame buildings is due to the need to increase the energy efficiency of enclosing structures. At the same time, defects at existing facilities are, for the most part, a consequence of insufficient experience in the design and construction of such facilities. The authors analyzed and summarized the causes of the most common defects in the facing layer of walls known in world scientific practice. Some results of experimental studies carried out by the authors on the strength of masonry under local compression in places where they rest on floor discs are presented. It was established that for masonry made of solid bricks, the compressive resistance Rcom at c = 0.5t decreased by 30% compared to the strength of masonry at c = t. For masonry made of hollow ceramic stones, the decrease in strength was even greater. Issues requiring study have been identified regarding the selection of anchors, the selection of insulation, the selection of mortar components and other equally important components of a complex structure in the form of an external layered wall.

Assessment of the effect of moisture on the strength of concrete and ceramic masonry wall products

Introduction. The material of the article considers the strength characteristics of ceramic and concrete masonry products, the operation of which is carried out in difficult conditions. The analysis of domestic and foreign publications and sources carried out in this work, including the results of previously performed experiments and field studies, showed that the values of the tensile strength of concrete and ceramic masonry products largely depend on moisture saturation.&#x0D; &#x0D; Aim. When analyzing previously performed works, it was found that moisture saturation and operating conditions significantly affect the strength properties of concrete and ceramic masonry products in the form of bricks and small blocks. It is noted that in some cases, the effect of degradation of the physical and mechanical properties of the products was observed. When performing surveys of buildings and structures, it becomes necessary to determine the bearing capacity of the masonry of foundations and basement walls located below the mark of the adjacent ground surface. These structures are located in an environment of excessive humidity, therefore, the masonry products themselves are in a state of increased moisture saturation, for example, due to the absence or damage of waterproofing, violation of the heat and humidity regime of the indoor microclimate.&#x0D; &#x0D; Materials and methods. During the work, masonry ceramic products in the form of bricks were used – new ones made according to State Standard 530-2012; historical bricks selected during the inspection of buildings and structures of historical buildings, as well as concrete wall products made according to State Standard 6133-2019. The test procedure complies with the established standard State Standard R 58527-2019.&#x0D; &#x0D; Results. Conducting of the research and developing of methods to assess the effect of humidification of ceramic and concrete masonry products on the strength of masonry is important for assessing the reliability of buildings and structures.&#x0D; &#x0D; Conclusions. The current problem requires comprehensive studies of the strength characteristics of ceramic and concrete masonry wall products, taking into account the influence of humidity.

Unreinforced masonry walls under two-way out-of-plane bending: Comparison of FE model predictions with analytical models

Four existing design guidelines based on the virtual work method have been compared to predict the out-of-plane (OOP) bending capacities of unreinforced masonry (URM) walls to one-way and two-way actions. The two-way OOP bending design equation as per the Australian masonry standard (AS 3700) and the three subsequent models developed by other researchers are based on specific wall geometries, support conditions, dimensions and strengths of masonry units and mortar. Due to limited experimental data available on URM walls under two-way bending, it is difficult to carry out a detailed investigation of the performance of these two-way design models against all the design parameters. This paper applies the finite element (FE) modelling technique to generate data and extensively investigate the influence of support conditions, pre-compression and aspect ratio on the two-way OOP bending capacity of URM walls. An explicit FE model previously developed by the authors where masonry is macroscopically modelled as an anisotropic composite material, is used for this purpose. Performances of three key parameters (i.e., moment capacity under horizontal bending and diagonal bending and torsional shear strength of masonry) that differentiate the four design models are investigated against varying levels of vertical pre-compression and flexural tensile strength of masonry. The OOP bending capacity predicted by the FE model is compared with the predictions of the design models. Results show that three out of four design models generally overpredict the two-way OOP bending capacities of square and taller walls. Further refinement to the AS 3700 design equation has been proposed in a modified model. The outcomes of this research will help to improve the design of masonry walls under OOP bending.

Survey and preliminary assessment of a baroque vault for refurbishment planning

Abstract Designing the modification of buildings for a new use is a costly and time-consuming process, before which it is often necessary to conduct a preliminary assessment of the feasibility of the intended project. The article discusses the procedure for such a preliminary cost-effective assessment using the example of a historic building with vaulted ceilings. For older historical buildings, archival documents specifying their geometry, construction details and material characteristics are typically not available. For the preliminary design, it is possible to obtain information about the dimensions of the load-bearing elements non-destructively. However, the knowledge of the exact material properties of the masonry exceeds the possibilities of an inexpensive assessment, which must take advantage of the data available in the literature for similar structures. This article presents a methodology and an example of the measurement and assessment of the mechanical response of the Baroque vault to static loading. It shows the process of obtaining data on the geometric shape of the structure by means of geodetic surveying and geometric radar measurements of the thickness of vaults whose upper faces are not accessible. Two models are used to calculate the internal forces in the structure. The first planar model considers a simplified barrel vault strip according to the focused geometry with respect to geometric nonlinearity and without tension, the second model is a linear spatial model of the entire vault. The calculation was performed in ANSYS 17.2, the input parameters of the material are taken from the literature. The calculated stresses in the vault are compared with the values of the design strength of brick masonry, taking into account the characteristic compressive strength of the masonry based on published known data obtained during tests of similar historical materials. The results are then used to decide on the feasibility of the intention to adapt the building for a new use.

Estimating the modulus of elasticity and the compressive strength of brick, mortar and masonry at different scales

This study includes extensive compression tests on clay brick units, gypsum mortar, and masonry configurations, incorporating both gypsum and cement mortar, across four distinct scales 1:1, 1:2, 1:4, and 1:6. It investigates the relationship between compressive strength and modulus of elasticity, with the aim of providing precise estimation tools for these important mechanical properties. Systematic experimentation is employed, and scatter diagrams illustrate the dynamic interplay between modulus of elasticity and compressive strength. The derived coefficients, validated against experimental data, verify the accuracy of the proposed relationships. Specifically, the derived coefficient η, representing the ratio of modulus of elasticity to compressive strength, exhibits scale-dependent variations. For brick units, η ranges from 104 for the 1:1 scale to 126 for the 1:6 scale, emphasising the impact of size. Additionally, the coefficient η for gypsum mortar demonstrates a 20% increase with a rise in the water-to-gypsum ratio. Regarding masonry configurations, the coefficient η in the BS method varies from 91 for the 1:6 scale to 139 for the 1:2 scale. In the RILEM method, the coefficient η ranges from 48 for the 1:6 scale to 105 for the 1:1 scale. The proposed relationships display a negligible deviation from experimental results, affirming their robustness. Furthermore, a relationship is introduced for estimating masonry compressive strength based on the compressive strength of both the brick and the mortar at different scales. The accuracy of this relationship is verified by its minor deviation from experimental results.

Shear Strength of Concrete Block Masonry Using Direct Shear Test

Shear Strength of Concrete Block Masonry Using Direct Shear Test

Experimental investigation of the compressive and shear behaviours of grouted and hollow masonry constructed with PVA fibre-reinforced mortar and grout

Polyvinyl alcohol (PVA) fibres are ultra-high-performance fibres that can be used to reinforce cementitious composites. This study experimentally investigated the compression and shear behaviours of grouted and hollow masonry constructed with fibre-reinforced mortar (FRM) used for the joints and/or PVA fibre-reinforced grout (FRG). In this regard, the effect of increasing the fibre content of 6 mm PVA fibres in the FRM on the behaviour of masonry was investigated. Moreover, the effect of changing the fibre length (8 mm and 13 mm PVA fibres) and the fibre content of 13 mm PVA fibres in the FRG on the behaviour of masonry was investigated. This was accomplished by constructing and testing 31 masonry prisms and 29 masonry assemblages. The behaviour of PVA-reinforced masonry was evaluated based on compressive strength, shear strength, modulus of elasticity, modulus of rigidity, compressive strain at peak compressive stress, shear strain at peak shear stress, compression ductility index and compression toughness. In addition, the compression and shear stress-strain curves, failure modes and crack propagation of PVA-reinforced masonry were compared with unreinforced masonry. It was concluded that using PVA fibres in the grout minimized the masonry face shell spalling, and most of the post-peak deterioration appeared in the form of masonry cracks and less face shell spalling compared with unreinforced masonry. In addition, using PVA-FRM only or PVA-FRM with PVA-FRG could increase the compressive strength of grouted masonry. In contrast, using PVA-FRM did not change the compressive strength of hollow masonry. Furthermore, all grouted assemblages with PVA-FRM and PVA-FRG (except for assemblages with 13 mm PVA-FRG with a fibre content of 0.10% by weight of grout) have similar average shear strength compared with unreinforced assemblages. Finally, As the fibre content of 6 mm PVA fibres in the FRM of hollow assemblages increased, the shear strength and the modulus of rigidity decreased. This study highlights the improvements and drawbacks of using PVA Fibres in mortar and grout on the compressive and shear performances of hollow and grouted masonry.

Detailed investigation of compressive and bond strength for sustainable brick masonry developed by using various types of bricks and green mortars

This experimental study attempts to clarify the compressive and bond strengths of sustainable brick masonry developed by combining three distinct types of bricks and three different types of green mortars, in comparison with the brick masonry comprising of control cement mortar. The masonry prisms were prepared by using handmade clay bricks (HB), fly ash bricks (FB), and machine-made clay bricks (MB) in addition to the control cement mortar (CM), fly ash mortar (FAM), bagasse ash mortar (BAM) and calcined clay cement mortar (C3M). The compressive strength of brick units and masonry mortar cube specimens was investigated. The compressive strength and flexural bond strengths were determined by conducting the tests on prisms composed of five stacked bricks and seven stacked bricks, respectively. While the masonry triplets were utilized to evaluate the shear bond strength of brick masonry. The experiments involving prisms and triplets were conducted at 14, 28, and 90 days to investigate the effect of curing age. The influence of mortar and brick compressive strength on the compressive strength of masonry prisms is also studied. The compressive strength of HB exhibited the highest value compared to both FB and MB. The C3M demonstrated superior compressive strength in comparison to alternative mortar types. As a result, the compressive, shear, and flexural bond strengths of HB-C3M prisms exhibited the highest values across all stages of curing in comparison to other types of masonry prisms. Since, it takes time for the compressive strength of BAM to develop, therefore, the masonry prisms made of BAM demonstrated better performance at longer age.

Influence of type of mortar and unit in the flexural strength parallel to the bed-joints of brick-mortar assemblages

According to EN 1996 Part 1-1, the flexural strength of masonry could be estimated based on information related mainly to the compressive strength of the mortar and the type of material of the unit. However, it is necessary to consider the impact of the interaction between components due to their physical characteristics, such as water absorption of the units and water retentivity of the mortar that may affect the bond between masonry components. Therefore, this paper evaluates the influence of the use of different types of mortar and units on the flexural strength parallel to the joints of masonry. For this, two types of mortar were considered: 1:1:6, and 1:0:5 (Cement: Lime: Sand), by volume. Regarding the units, two types of clay bricks of different geometric configuration (solid and frogged) were chosen. Thus, four combinations of units and mortar types were considered for the construction of the masonry wallets according to the guidelines indicated in EN1052-2. Flexural strength parallel to the bed-joints was tested according to EN1052-2, and compressive strengths of mortar specimens were controlled in accordance with EN1015-11 for the age of 90 days. In addition, characteristics of the units and water retentivity of mortars were also evaluated. The results showed that the compressive strength of the mortar is a significant factor if the failure occurs at the mortar bed-joint and not at the interface between components.