Masonry Walls Research Articles

In-Plane Structural Analysis of Coated Masonry Walls via a Homogenized Model

In-Plane Structural Analysis of Coated Masonry Walls via a Homogenized Model

Farklı Duvar ve Harç Malzemeleri İle Üretilen Duvarların Mekanik Özelliklerinin Belirlenmesi

Walls produced using different masonry materials and mortars are among the structural elements that carry horizontal and vertical loads. In this context, the mechanical properties of walls produced with different wall and mortar materials have been investigated. In the production of wall samples, Harman Brick (HB), Masonry Brick (MB) and Bimsblok (BB) were chosen as the mesh material Reinforced Mortar (RM) and Polypropylene Fiber Added Mortar (PM) were used as binding materials in the construction of the walls produced in 900x900 mm dimensions. The volumetric mixing ratios of the mortar used were prepared as sand:cement:lime=6:1:1, according to the TSE 2510 standard. The bricked wall samples were subjected to diagonal loading tests after being kept in the laboratory environment for 28 days. Flexural and compressive strengths of the mortars used in wall building, displacement values of the walls, shear strength, rigidity modulus, energy absorption capacity and collapse patterns of the walls were determined. The graphs of the displacement values obtained by examining the behaviors observed in the test samples and the cracks formed were interpreted. It was observed that the shear strength of the walls built using PM was higher than the shear strength of the walls built using RM. The energy absorption capacity was highest in the fibrous specimen laid with masonry bricks. The average vertical load value of the wall specimens built with fibrous mortar, which is the BB of the masonry material, was 30% higher than the specimens built with non-fiber mortar.

Improving In-Plane Behavior of Weak Brick Masonry Walls Through Assimilation of Partially Confining RC Bands

ABSTRACT In this work, a numerical study is conducted to investigate the improvement of in-plane behavior of weak brick masonry walls through assimilation of partially confining horizontal and vertical reinforced concrete (RC) bands. The bands are considered to be assimilated with the existing walls by cutting grooves over the partial thickness of the wall in a easy-to-construct manner. For numerical modeling of the wall width and without partially confining elements, a three-dimensional (3D) macro-modeling approach is utilized as it is computationally efficient compared to other modeling approaches while representing the global behavior reasonably well. The components of macro-models are discretely modeled. The concrete damage plasticity (CDP) model is considered to describe the non-linear behavior of the concrete and masonry for crushing and cracking failures. Steel reinforcements are considered as bilinear with hardening and modeled with perfect adhesion with the surrounding concrete using embedded constraints. Experimental results obtained from the full-scale tests at the Structural Engineering laboratory of IIT Kanpur have been utilized to validate the numerical model. The responses obtained from the numerical model of both with and without RC bands demonstrate that the models reasonably capture the experimental behavior such as initial stiffness, peak loads and post-peak behavior. The initial peak load from the numerical model of without and with RC bands was found to be 3.2% and 6.9% lower than the experimental value, respectively. Although post-yield trends of numerical and experimental results show similar behavior for walls without and with RC bands, the numerical model underestimates the post-yield strength for the wall without RC bands. This deviation can be attributed to the masonry dominated post-peak behavior coupled with modeling assumptions and values of model parameters used for the numerical analysis. Finally, to understand the influence of various parameters on lateral strength, a parametric study has been conducted. From the parametric study, it has been found that the compressive strength of masonry and band aspect ratio are the two most important parameters governing the strength of the wall. Finally, it is noted that a wall with band aspect ratio close to unity provides superior ductile behavior.

Improvement of the thermal performance of hollow clay bricks for structural masonry walls

Although structural masonry walls are widely used in construction, achieving lower U-value is crucial to minimize energy losses and greenhouse gas emissions. The effect on the U-value of hollow clay masonry walls is evaluated by modifying the clay and mortar thermal conductivities, as well as the brick grid and thickness. Heat transfer through bricks and walls was modeled using a 3D-finite element method while model validation was based on experimental tests. Smaller rectangular cavities reduce the U-value to 0.761 W/m2K; increasing the brick thickness reduces the U-value to 0.563 W/m2K. Moreover, reducing the clay thermal conductivity showed negligible reductions in the wall U-value.

Cement-Based Mortars with Waste Paper Sludge-Derived Cellulose Fibers for Building Applications

This study assesses the mechanical properties of mortars incorporating waste paper sludge-derived cellulose fibers. Compression and flexural tests were carried out on specimens prepared with cellulose fibers at different proportions, ranging from 0% to 2% of the total weight of the solid mortar constituents (cement, sand, and lime). In addition, a comparative analysis was carried out to evaluate the influence of the preparation method on the mechanical properties of the mortars. To this end, two series of mortars were studied: one prepared following a rigorous control of the preparation parameters and the other made without systematic parameter control to simulate typical on-site conditions. Finally, the applicability of both traditional and eco-friendly mortars in the construction of small-scale masonry walls was assessed through compression tests. Overall, the mechanical properties of mortars with cellulose fibers were comparable to those with 0% waste material, regardless of the production process. Regarding the compressive behavior of masonry walls, experimental tests showed significant similarities between specimens made with traditional and eco-friendly mortar. In conclusion, incorporating cellulose fibers into cement-based mortar shows considerable potential for building applications, enhancing the environmental benefits without compromising the mechanical behavior.

Resistance of natural stone masonry wallettes under centred and eccentric compressive loading: Experimental and numerical approaches

Masonry walls are typically subjected to eccentric compressive loadings in common buildings. However, the design of walls towards this type of solicitation remains very empirical, often leading to oversizing the structure. This is especially true for natural stone masonry, for which experimental data are quite scarce. This paper presents an experimental campaign on 15 natural stone masonry wallettes subjected to centred and eccentric compression until failure. Different values of the eccentricity of the load, ranging from h/12 to h/4 (where h is the thickness of the wallette) were investigated, highlighting the noticeable effect of such a value on the compressive failure load. During the tests, the displacements were recorded by a Digital Image Correlation system, providing insights into the different failure mechanisms that depend on the value of the eccentricity. The so-obtained experimental failure loads are then compared to the predictions of Eurocode 6. Finally, a finite-element yield-design analysis of these tests is proposed which shows that this modelling framework is suitable to find the ultimate bearing capacity of a masonry wallette.

COMPARATIVE ANALYSIS OF COSTS AND TIMES OF RED BRICK AND LIGHT BRICK WORK ON THE MADRASAH MALLIMIN MUALLIMAT TAMBAK BERAS JOMBANG BUILDING PROJECT

The problem in implementing the construction of the Madrasah Muallimin Muallimat Tambak Beras Jombang Building is that the available funds and time are limited. The approach regarding the material needed for this building work is light brick compared to other work items. In wall masonry work using light brick/hebel, it is necessary to analyze whether the work time can be faster and whether the price comparison obtained is cheaper. The research method used is Value Engineering analysis to produce cost savings. The results of this research include: a) Based on the results of cost and time analysis for wall items, namely by proposing alternative materials as replacements for the initial materials, resulting in cost savings of Rp. 28,298,995.61, and b) When compared with productivity, a builder is able to complete a red brick wall in 133 days, whereas with light brick wall material a builder is able to complete the work in 66 days. So, in terms of work speed, lightweight bricks are faster than red brick walls.

An Investigative Study for the Seismic Performance of Composite-Reinforced Masonry Wall with Prestressing Technology

Prestressing technology is an effective way to improve the seismic performance of masonry structures such as concrete masonry wall. Therefore, bonded prestressing technology applied to integrated concrete masonry wall (ICMW) was proposed in this study, and a cyclic loading test on specimens with different section types was conducted. It was found that the prestressing technology rendered thinner and denser cracks on the load-bearing component of the specimens, while the failure mode remained unchanged. The prestressing technology increased the initial stiffness of the specimens and accelerated their stiffness degradation. Although the prestressing technology advanced the yield displacement of the specimens, it had a positive influence on the displacement ductility of the specimens. Additionally, the energy dissipation of the specimens increased with the deepening of the damage state, while the influence of the prestressing on the energy dissipation of the specimens decreased with an increased in the drift ratio. Furthermore, the equivalent viscous damping of the specimens with a rectangular and T-shaped section finally converged at 8% and 14%, respectively. Overall, the aforementioned findings indicate that the prestressing technology proposed in this study is a useful method for improving the damage propagation and seismic performance of ICMW, which could be used to construct low-rise masonry structures in the future.

Improved Bond Stress-Slip Relationships for Carbon Fibre-Reinforced Polymer-Strengthened Masonry Triplets

Carbon fibre-reinforced polymer (CFRP) emerges as a viable solution for reinforcing unreinforced masonry (URM) walls subjected to shear loads. While masonry structures are straightforward to construct, the complexity of the construction materials, especially in terms of their mechanical properties, poses challenges for numerical studies of their structural behaviour. Walls, being fundamental components in masonry construction, play a crucial role in transferring both horizontal and vertical lateral forces. This study investigates the enhancement of masonry wall behaviour through the reinforcement of CFRP. CFRP reinforcement increases ductility and strength, reducing the risk of failure under shear conditions. Additionally, CFRP composites present a practical solution to strengthening masonry structures compared to traditional reinforcement. However, brick, mortar, and CFRP have not been thoroughly investigated. Experimental tests on the bond behaviour of different configurations of CFRP-retrofitted masonry triplets have not been performed before and are therefore presented in this paper. Triplet specimens, comprising three bricks and two mortar joints, both with and without CFRP strengthening, were subjected to bond testing. The study affirms that masonry triplets strengthened with CFRP under shear loads exhibit strength levels at least four to six times greater than those without CFRP. The experimental work was carried out with eight different CFRP configurations on triplet masonry, and each test was repeated four times. Further, the bond stress-slip relationship in the case of masonry triplets with and without CFRP was predicted with new mathematical equations based on the conducted test results. These equations were included in the commercial finite element software ANSYS and used to conduct simulations of CFRP-reinforced masonry triplets. The numerical results indicate good agreement between the finite element model and the test results. The outcome of this research improves the current knowledge on the use of CFRP to reinforce masonry walls with brick and mortar, which will contribute to the understanding of the effect of CFRP on masonry structures.

Drying of an aerogel-based coating system in Swedish climates: Field tests and simulations

Aerogel-based coating mortars (ACM-systems) introduce new solutions for energy-retrofit of uninsulated building envelopes, preserving their characteristics while minimizing the material thickness. However, when introducing new solutions, the long-term durability needs to be investigated. The hygrothermal (heat and moisture) performance is one aspect that needs to be secured. The aim of this study is to investigate the hygrothermal performance, with specific focus on moisture drying, of an ACM-system for external applications in Swedish climates. A field test was conducted where an ACM-system with 40 mm of ACM was applied on the exterior of a brick masonry wall partition. The temperature and relative humidity in the wall were monitored for 15 months. Furthermore, numerical hygrothermal simulations were used to predict the early stage drying and long-term performance of the ACM-system in four Swedish climates. The field measurements showed that the built-in moisture dried out after approximately 6 months, after which the ACM-system followed the variations in the surrounding climate for the remaining period. The simulations predicted that the early stage drying time ranged from 134 to 336 days, depending on climate and time of application. Furthermore, the elevated relative humidity in the ACM due to rainwater absorption resulted in an average thermal conductivity of up to 9 % above the rated value. Consequently, mitigating water absorption at the exterior is crucial for enhancing the long-term thermal performance in high rain load scenarios.

Failure mode dependent shear strength of unreinforced concrete brick masonry wall panels

This study conducted diagonal compression tests to propose the failure mode dependent shear strength for unreinforced concrete brick wall panels. The test variable was the bed-joint mortar mixing ratio. Six brick wall panels were manufactured for each variable, and finally thirty specimens were tested. The test results showed five failure modes in the unreinforced masonry wall panels: diagonal tension, combined, bed-joint sliding, toe crushing, and non-diagonal failure. Furthermore, the shear strength of unreinforced brick wall panels was highly dependent on the failure mode. Based on the test results, the shear strength is suggested according to each failure mode. Additionally, the shear modulus of concrete brick wall panels was suggested as half of the value presented in the current codes for masonry structures.

Experimental Study on the Seismic Performance of Brick Walls Strengthened by Small-Spaced Reinforced-Concrete–Masonry Composite Columns

Through low-cycle reciprocating tests on 11 masonry wall specimens strengthened using reinforced-concrete–masonry composite columns, the effects of the position of the composite column, height-to-width ratio, column reinforcement ratio, and axial load ratio on their load-carrying capacity, stiffness, ductility, and energy dissipation capacity were investigated. It was experimentally found that, by strengthening brick walls with RC–masonry composite columns, the concrete and masonry parts can work together effectively, the failure mode shifts from shear to flexural failure, and the strengthened walls exhibit improved bearing capacity, ductility, and energy dissipation performance compared to unstrengthened masonry walls. It is suggested the composite columns can be placed at the ends of the wall if a strengthening measure is required. For walls with height-to-width ratios greater than 1, placing composite columns in the middle of a wall has little effect on the bearing capacity and stiffness of the wall but can improve the ductility of the wall. The height-to-width ratio is a primary factor influencing the structural performance of masonry walls strengthened using composite columns. A smaller height-to-width ratio leads to higher load-carrying capacity and stiffness but may result in reduced ductility. In comparison, the impact of the column reinforcement ratio and axial load ratio is relatively weaker. The flexural capacity of the masonry wall after strengthening can be obtained using the calculation method for concrete members subjected to a combined action of flexure and compression, in which the compressive strength of the masonry is considered.

Reliability updating for lateral failure of historic quay walls

ABSTRACT The historic canal walls of Amsterdam, stretching 200 km in total, are constructed as a masonry wall on a timber deck supported by vertical timber piles. Understanding the resistance against lateral failure of these quays has been challenging due to uncertainties in their working principles, geometry, soil and structural properties. This paper proposes a Bayesian approach to include evidence from past loading situations and corresponding deformations into the reliability assessment. This approach enables refinement of the reliability predictions and parameter distribution uncertainties, leading to a more accurate prediction of the resistance against the lateral failure of historic quay wall. Depending on the type of evidence, an a-priori reliability prediction for a quay wall that fails to meet safety standards can be updated to any of the three consequence classes outlined in NEN8700. In a case study, a quay wall with an a-priori reliability of β = 1.5 has been increased to β = 3.2 by including evidence of an extreme survived load of 10 kN/m2 that resulted in displacements of less than 4 mm. This is a decrease in failure probability by two orders of magnitude, showing the potential impact of using observational information in combination with Bayesian updating.

Exploring the Cyclic Behaviour of URM Walls with and without Damp-Proof Course (DPC) Membranes through Discrete Element Method

Unreinforced masonry (URM) walls are common load-bearing structural elements in most existing buildings, consisting of masonry units (bricks) and mortar joints. They indicate a highly nonlinear and complex behaviour when subjected to combined compression–shear loading influenced by different factors, such as pre-compression load and boundary conditions, among many others, which makes predicting their structural response challenging. To this end, the present study offers a discontinuum-based modelling strategy based on the discrete element method (DEM) to investigate the in-plane cyclic response of URM panels under different vertical pressures with and without a damp-proof course (DPC) membrane. The adopted modelling strategy represents URM walls as a group of discrete rigid block systems interacting along their boundaries through the contact points. A novel contact constitutive model addressing the elasto-softening stress–displacement behaviour of unit–mortar interfaces and the associated stiffness degradation in tension–compression regimes is adopted within the implemented discontinuum-based modelling framework. The proposed modelling strategy is validated by comparing a recent experimental campaign where the essential data regarding geometrical features, material properties and loading histories are obtained. The results show that while the proposed computational modelling strategy can accurately capture the hysteric response of URM walls without a DPC membrane, it may underestimate the load-carrying capacity of URM walls with a DPC membrane.

Utilizing advanced machine learning approaches to assess the seismic fragility of non-engineered masonry structures

Seismic fragility assessment provides a substantial tool for assessing the seismic resilience of these buildings. However, using traditional numerical methods to derive fragility curves poses significant challenges. These methods often overlook the diverse range of buildings found in different regions, as they rely on standardized assumptions and parameters. Consequently, they may not accurately capture the seismic response of various building types. Alternatively, extensive data collection becomes essential to address this knowledge gap by understanding local construction techniques and identifying the relevant parameters. This data is crucial for developing reliable analytical approaches that can accurately derive fragility curves. To overcome these challenges, this research employs four Machine Learning (ML) techniques, namely Support Vector Regression (SVR), Stochastic Gradient Descent (SGD), Random Forest (RF), and Linear Regression (LR), to derive fragility curves for probability of collapse in terms of Peak Ground Acceleration (PGA). To achieve the research objective, a comprehensive input/output dataset consisting of on-site data collected from 646 masonry walls in Malawi is used. Adopted ML models are trained and tested using the entire dataset and then again using only the most highly correlated features. The study includes a comparative analysis of the efficiency and accuracy of each ML approach and the influence of the data used in the analyses. Random Forest (RF) technique emerges as the most efficient ML approach for deriving fragility curves for the surveyed dataset in terms of achieved lowest values for evaluation metrics of the ML methods. This technique scored the lowest Mean Absolute Percentage Error (MAPE) of 16.8 %, and the lowest Root Mean Square Error (RMSE) of 0.0547. These results highlight the potential of ML techniques, particularly RF, in derivation of fragility curves with proper levels of accuracy.

A novel semi-empirical approach to non-destructively evaluate the effect of infills on frame buildings

Masonry infilled frame (MIF) structures are commonly used as building system in many regions, and particularly in Latin American, Mediterranean, and Pacific countries, which are areas highly exposed to seismic events. It is well known that the influence of the infilled frames on the seismic response is affected by several sources of uncertainties which create unsafe unaccuracies in the seismic behaviour of a building. The use of existing complex models is an option which require a large number of specialized input values and data mostly obtained from in-situ destructive tests, thus making them infeasible in many practical cases. This research is a first attempt to provide an approach which provides prediction of the structural behaviour of a MIF with quantified uncertainty, and using as inputs values that can be obtained through a low-cost non-destructive test. The proposed method exploits the known interaction between the in-plane (IP) and out-of-plane (OoP) behaviour of the masonry wall by providing a semi-empirical model which predicts the IP stiffness of the MIF in terms of the measured OoP fundamental frequency. The semi-empirical approach has been nurtured with five experimental tests over one-fourth scale MIFs, where the OoP fundamental frequency variation has been obtained in terms of the IP deformation history. The results indicate that the proposed method can become a practical tool to experimentally quantify the contribution of the masonry infills of existing frame buildings, and also to theoretically predict it during design phase. However, a larger dataset of tests should be used on the calibration of the method before its application in real cases.

Conditional diffusion model-based generation of speckle patterns for digital image correlation

Generating speckle images is crucial for calibrating errors in digital image correlation (DIC) algorithms, alleviating the scarcity of training data for deep learning-based DIC algorithms, and even for the broader application of digital speckle methods. Traditional methods for speckle image synthesis struggle to accurately replicate the brightness variations in the foreground and background of realistic speckle images, and these methods come with high computational costs. Additionally, there needs to be more scientific and systematic evaluation methods for the quality of generated DIC speckle images. Our study presents a high-fidelity method for generating DIC speckle images with cracks based on a conditional diffusion model. We established evaluation metrics for generated DIC speckle images based on multiscale spatial and spectrum domains. We verified them on an open-source dataset of DIC speckle images depicting cracks in stone masonry walls. The conditional diffusion model excels at forward tasks (DIC crack image segmentation) and inverse tasks (DIC speckle image generation), with particular strength in the latter. The proposed spatial and multiscale spectrum domain metrics allow for the comprehensive and accurate evaluation of the alignment between the synthetic and natural speckle images. The conditional diffusion model for DIC speckle image generation and evaluation proposed in this paper has the potential to enhance further the accuracy and robustness of DIC technology in experimental mechanics and engineering applications.

Natural Fiber Textile Reinforced Mortar (NFTRM) for Integrated Masonry Upgrading

The construction and building industry is responsible for a significant amount of carbon emissions due to its high energy consumption throughout the lifecycle of buildings. Many masonry buildings were constructed without following any seismic or energy standards, making them vulnerable to both natural and man-made disasters.This paper discusses the use of a Natural Fiber (NF) in the Textile Reinforced Mortar (TRM) system, to upgrade or retrofit masonry walls, addressing both structural and thermal issues.During this campaign, various jute fiber products have been used to upgrade or retrofit the masonry wall to achieve a balanced thermo-structural property for the NFTRM system. Notably, jute fiber nets (with mesh type “2.5 cm x 2.5 cm”) and diatons have been used to enhance the strength of the masonry wall. For the thermal upgrading of masonry walls, a combination of 30 mm jute fiber length and 1% jute fiber (based on the dry mortar mass) was chosen for composite mortar preparation.The use of the jute NFTRM system has resulted in an increased load-bearing capacity (kN) of more than 450% and whereas, an improved insulation capacity, with a reduction of thermal transmittance (W/m2K) of about 36% have been observed for the upgraded masonry wall, when compared to the un-strengthened masonry wall.

Investigation of the bed joint reinforcement effect on the drift capacity of modern unreinforced masonry walls

Bed joint reinforcement significantly affects the shear capacity of masonry walls due to its effective ability to transfer shear forces through a diagonal crack, but how does this phenomenon impact its drift capacity? This paper presents an experimental study containing a series of four quasi-static cyclic tests conducted on masonry walls of same size. Two of them incorporated truss-type bed joint reinforcement, while the other two were completely unreinforced. All specimens were subjected to double bending boundary conditions to observe shear-controlled behaviour and were tested under two levels of compression load. The primary objective of this research is to determine the role of horizontal reinforcement in the seismic properties of unreinforced masonry walls focusing on the displacement capacity. The findings from this experimental study are expected to provide empirical evidence for subsequent numerical simulations and contribute to the development of analytical formulations. The results aim to enhance our understanding of the seismic response of masonry walls, ultimately informing design practices and seismic retrofitting strategies.

Mixed Model and Gaussian Process to Investigate the External Influence on the Propagation Time of Ultrasonic Waves on Masonry Walls

The ultrasonic testing has been considered a promising method for diagnosing and characterizing masonry walls. As ultrasonic waves tend to travel faster in denser materials, their use is common in evaluating the conditions of various materials. Presence of internal voids, e.g., would alter the wave path, and this distinct behavior could be employed to identify unknown conditions within the material, allowing for the assessment of its condition. Therefore, we applied mixed models and Gaussian processes to analyze the behavior of ultrasonic waves on masonry walls and identify relevant factors impacting their propagation. We observed that the average propagation time behavior differs depending on the material for both models. Additionally, the condition of the wall influences the propagation time. Gaussian process and mixed model performances are compared, and we conclude that these models can be useful in a classification model to automatically identify anomalies within masonry walls.