Stone Masonry Walls Research Articles

Experimental and Numerical Investigation on Strengthening Techniques for Double-Wythe Stone Masonry Walls

Masonry structures represent the architectural and cultural heritage of great historical importance. They have been used for public and residential buildings for several thousand years. Many well-preserved old masonry structures still exist, proving that this construction can overcome loads and environmental impact. These structures have been exposed to lateral and vertical loads and atmospheric influences throughout their lives. In masonry structures, undesirable damage, cracks, and voids may occur due to environmental factors or various natural disasters, such as earthquakes, which may cause the structure to collapse. Different conventional strengthening techniques are available depending on the purpose required for stone masonry walls. This study aims to evaluate the structural behavior of double-wythe travertine stone masonry walls strengthened by carbon fiber reinforced polymer (CFRP). For this purpose, two masonry stone walls, which are made of saw-cut travertine stones and constructed with English bond, a pattern formed by laying alternate courses of stretchers and headers, were constructed and tested under in-plane monotonic lateral load and constant axial load. Lateral load-displacement relations and failure mechanisms were discussed. In addition, triaxial compression tests of stone, mortar, grout, and stone-mortar composite materials were performed to determine constitutive relationships. Furthermore, three-dimensional (3D) nonlinear finite element analysis (NLFEA) of stone masonry walls using the Drucker-Prager (DP) yield criterion was performed for unstrengthened stone masonry walls and strengthened ones with grout injection and CFRP. The study findings revealed that the proposed numerical modeling approach can accurately predict the experimental lateral load-displacement behavior of both strengthened and unstrengthened specimens subjected to in-plane combined axial loading and shear. Additionally, the model demonstrated its capability to simulate the experimental load-displacement and cracking patterns effectively.

Seismic Resilience of Geogrid Reinforced Concrete Earth-Retaining Wall of Various Incremental Panels Based on Physical and Numerical Modelling

The dynamic response for different earth-retaining walls having geogrid as a reinforcement, combined with cohesionless granular material for backfill to mitigate earth pressure, has been examined through scale-down shaking table experiments and full-scale 3D FE analysis, utilizing ABAQUS as the finite element software. The scale factor is 1/4th for scaled-down. This study included various physical modelling experiments using different geogrid-reinforced earth retaining (GRER) walls (1m height, 7.5cm, thickness, and length 1m). Additionally, comprehensive 3D finite element analysis were conducted with the configurations measuring (4m, height 0.3m, thickness, and length 4m). This study examines hollow prefabricated concrete panels with shear key (PC-W), stone masonry walls of gravity type (GM-W), and traditional reinforced concrete (RC-W) walls. It also presents comparative investigations, such as lateral horizontal displacement of the wall, lateral pressure to the backfill, backfill soil settlement, and settlement of the wall foundation of various (GRER) walls. The accuracy of the Finite Element simulation framework has also been assessed in the shaking table experiment, as well as the FE analyses. According to the results, a PC-W wall with a shear key is the most effective type because it shows more resistance toward displacement. As per the comparison of the test models, GRER walls’ seismic response was more affected by the earthquake waves from the far field having long-term high acceleration values. In contrast, seismic waves from the close field had a smaller impact on the walls’ seismic response. However, the geogrid could improve the GRER seismic resilience deformation. Geogrid layers may reduce backfill pressures and backfill settlements. The geogrids located in the central portion within the reinforced soil and the geogrid roots connected to the walls were essential to the seismic design of the geogrid-reinforced earth retaining wall. To evaluate the reliability of the findings, the models have a predicted R2 variance below 0.1, indicating a consistent relationship between these two variables.

Natural materials modified mud mortar for rubble stone masonry: An experimental and numerical study

Rubble stone masonry is a long-standing construction. However, its binding material and mud mortar exhibit shortcomings, including low tensile and shear strength and poor water resistance. To overcome these limitations, researchers have initiated investigations into modifying mud mortar, specifically focusing on the influence of natural materials on their performance. This study used straw (0-1wt%) and starch (0-7wt%) as modifiers for mud mortar. The modified mortar underwent compression, straight shear, split tensile, water immersion, and abrasion tests to investigate its mechanical properties and water resistance. Additionally, electron microscope scanning was employed to reveal the modification mechanism of mud mortar at the microstructural level. The study results showed that 0.5wt% straw/ 5wt% starch was the optimal blended mortar. In contrast, for compressive strength, tensile strength, cohesion, and water absorption capacity, starch was better than straw, and for internal friction angle and abrasion resistance, straw was better than starch. The modification mechanisms of both were bridging and gelling effects, respectively. Lastly, finite element numerical simulations were employed in this study to analyze how modified mud mortar influences the shear performance of rubble stone masonry walls. The results demonstrated that adding both straw and starch substantially enhanced the shear strength and ductility of the walls. Specifically, the additions of 0.5wt% straw and 5wt% starch increased the shear strength by 18.12% and 9.1% and the ductility by 8.48% and 0.83%, respectively. This study significantly advances low-carbon, green buildings, and sustainable development.

Biaxial shaking table tests on a full-scale single-storey traditional Greek stone masonry and timber-framed composite structure

Biaxial shaking table tests were carried out on a full-scale, single-story specimen of a traditional Ottoman-period Greek structure, comprising a stone masonry wall with timber ties and three timber-framed masonry walls with fired clay brick infill. Timber posts and beams were connected with cylindrical mortise-tenon joints. The dynamic characteristics before and after seismic testing were determined with sine sweep tests. The specimen proved capable of withstanding peak ground accelerations equal to the highest seismic zone of Greece. Most damage concentrated in the stone wall, while rocking behavior at the post-sill-beam joints was observed for the timber-framed ones, which only showed minor damages. Finally, interventions are suggested based on the experimental results.

Experimental on-site measurement of thermal conductance by means of heat flow meter applied to nanocomposite thermal insulating mortar coating

Abstract In the energy refurbishment of buildings, the declared thermal conductivity is the key to meet the minimum requirements concerning energy efficiency and tax incentives. Regardless of the assessment method for thermal conductivity, in situ measurements using the heat flow meter technique can be always performed, especially in case of very low and self-declared thermal conductivities. In the present work, the reliability of the heat flow meter approach is validated considering a multilayer wall, with all thermal properties declared by means of technical regulations or CE marking. The measured total conductance of the wall is in very good accordance with the calculated one. Then, the heat flow meter has been applied to a plastered stone masonry wall before and after the application of a nanocomposite, thermal insulating, mortar coating 8 mm thick, with a self-declared thermal conductivity of 0.0019 W/(m K) without CE marking or appropriate laboratory tests. The thermal conductance obtained from the on-site measurements is about five times greater than the expected one. The increase in thermal resistance due to the mortar is comparable to a material with the same thickness, but with the thermal conductivity one order of magnitude greater than the self-declared value.

Topological data analysis-based damage indices for plastered stone masonry walls under cyclic loading

The qualitative aspect of visual inspection of damaged structures can be largely benefited by incorporating quantitative metrics. Moreover, automating this process requires the development of effective computational tools capable of making reliable assessments, appropriately calibrated to the mechanical and structural characteristics of the systems under analysis. In this paper, two damage indices are determined based on the topology of crack patterns. The results of an experimental campaign involving six plastered stone masonry walls are used to show that, for walls constructed with uncut limestone blocks and pebbles, these damage indices are correlated with strength degradation. To this end, topological data analysis is employed to estimate persistent diagrams and minimum spanning trees of crack patterns extracted from digital images using convolutional neural networks and signal processing techniques. The results show that the topological complexity of crack patterns is a strong indicator of the damage level in structures.

Applying a 2D Variational Rigid Block Modeling Method to Rubble Stone Masonry Walls Considering Uncertainty in Material Properties

ABSTRACT The computational cost of detailed micro-modeling of masonry structures can be minimized with rigid block analysis methods, where a variational formulation is particularly interesting as it allows for nonlinear pushover analysis. This work investigates the accuracy of this modeling method in predicting the response of rubble stone masonry walls in shear compression tests. To this end, we extend the mathematical programming problem by including cohesion, compressive strength, and tensile strength in the formulation and implement an improved pushover procedure, which guards compatibility of the displaced shape and crack patterns at the intersection of elastic and rigid contact models. Additionally, we reduce model uncertainty, introduced through sampling material properties with distributions estimated based on results from tests on mortar masonry joints and on mortar specimens, by correlating the predicted crack patterns with the observed ones. The findings show that (i) model falsification based on crack pattern is an effective method for reducing the parameter uncertainty of stone masonry walls; and that (ii) the improved pushover procedure predicts the pre- and post-peak response of stone masonry walls very well with analysis times of less than 20 minutes for 2D models where stones and mortar are modeled explicitly.

Shear Strengthening of Stone Masonry Walls Using Textile-Reinforced Sarooj Mortar

Most historical buildings and structures in Oman were built using unreinforced stone masonry. These structures have deteriorated due to the aging of materials, environmental degradation, and lack of maintenance. This research investigates the physical, chemical, and mechanical properties of the local building materials. It also presents the findings of an experimental study on the in-plane shear effectiveness of a modern strengthening technique applied to existing stone masonry walls. The technique consists of the application of a textile-reinforced mortar (TRM) on one or two faces of the walls. Shear loading tests of full-scale masonry samples (1000 mm width, 1000 mm height, and 350 mm depth) were carried out on one unreinforced specimen and six different cases of reinforced specimens. The performances of the unreinforced and reinforced specimens were analyzed and compared. We found that strengthened specimens can resist in-plane shear stresses 1.5–2.1 times greater than those of the unreinforced specimen; moreover, they demonstrate ductility rather than sudden failure, due to the presence of fiberglass and basalt meshes, which restrict the opening of cracks.

Simulating the damage of rubble stone masonry walls using FDEM with a detailed micro-modelling approach

Simulating the damage of rubble stone masonry walls using FDEM with a detailed micro-modelling approach

Dynamic characteristics of stone masonry walls before and after damage: Experimental and numerical investigations

Seismic behavior of masonry walls has been heavily investigated, especially by means of laboratory experiments employing cyclic tests to determine the mechanical parameters and seismic capacity. Nevertheless, the dynamic properties of the tested walls often remain unknown, even though the nature of the seismic response is dynamic and profoundly affected by the structure's dynamic properties. This paper presents an investigation on the dynamic properties of three different masonry wall panels in healthy and damaged states, and examines if damage quantification via tracking the changes in dynamic properties is feasible. Ambient vibration and impact measurements are used for the dynamic identification of wall panels, before and after they are tested in reversed-cyclic in-plane shear-compression tests. The natural frequencies, damping ratios, and mode shapes of the walls are determined and compared to each other. Moreover, the damage progression and its effect on the dynamic features of the URM wall panel is investigated using a discrete element model of the benchmark wall that is validated in terms of the force-displacement response and damage pattern of the wall. The results of the study indicate that changes in natural frequencies and mode shapes are traceable, although it is difficult to infer damage quantification relationships from these changes. The outcomes of this study also highlight that numerical models verified with the nonlinear quasi-static behavior do not necessarily match the wall's dynamic behavior, and that more research is required to update nonlinear numerical models. Overall, the results contribute to the knowledge regarding the dynamic characteristics of masonry walls in healthy and damaged conditions, and to quantify the damage in masonry walls as well as the changes in their dynamic properties.

An image convolution-based method for the irregular stone packing problem in masonry wall construction

The use of natural stones as building material can help reducing the carbon footprint of the construction industry. However, their non-uniform shapes makes the construction of stone masonry structures challenging. Therefore, the development of efficient algorithms for the stacking of irregular stones obeying structural and architectonic requirements is essential. In this paper, we propose an image-based method for automating the stacking of non-uniform stones in the construction of 2D load-resistant stone masonry walls. Stone wedging, a traditional technique employed by skilled masons, is implemented to reinforce the stability of stone placements. We use image processing for accelerating the stone selection and placement, and determine the wall’s resistance using a variational rigid-block modeling approach. It is demonstrated that the developed method is efficient and robust in challenging conditions. The analysis of the computational performance of the presented method shows that it is suitable for automated construction.

Enhancing the fiber-based modeling approach for flexure-shear behavior in seismic evaluation of long-span railway masonry arch bridges

Masonry arch bridges are considered a significant part of the rail and road transportation infrastructures in many countries, and seismic assessment of these structures is of great importance for increasing their resilience. Despite some shortcomings in comparison to more complicated modeling techniques, i.e. continuous and discrete techniques, one-dimensional continuous modeling approaches such as the fiber beam approach are more practical for engineering purposes. Although the fiber models can acceptably predict the axial and flexural behavior of structural members, shear or flexure-shear failure behavior, which could be one of the dominant failure modes in masonry structures, cannot be predicted appropriately in this approach. The purpose of this article is to enhance fiber-based modeling approach to consider these brittle failure modes for the seismic assessments of long-span masonry arch bridges. Using the existing analytical-empirical prediction equations reported on the results of stone masonry walls, an iterative approach is proposed to enhance fiber-based model to include flexure-shear interaction. the proposed method is verified with a series of arch samples with different geometric properties with results from discontinuous models of the sample arches. Following that, different models of a span of a case-study masonry arch bridge is created, verified with health monitoring field observation, and analyzed to compare from different aspects and validate the application of the fiber beam method along with its enhancements. The results of the proposed method for fiber models show promising conformity with the results of more precise numerical models, and it can be used for the seismic evaluation of long-span stone masonry bridges.

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.

Numerical model for the cyclic behaviour of a rubble stone masonry wall with opening and reinforcement

Numerical model for the cyclic behaviour of a rubble stone masonry wall with opening and reinforcement

Numerical model for the cyclic behaviour of a rubble stone masonry wall with opening and reinforcement

Numerical model for the cyclic behaviour of a rubble stone masonry wall with opening and reinforcement

Roman stone masonry walls: The application of Ground Penetrating Radar to ancient structures

An investigation on estimating Roman stone masonry wall thickness using non-invasive Ground Penetrating Radar (GPR) and Light Detection and Ranging (LiDAR) technology is presented in this paper. Historical building conservation and structural evaluation require correct wall thickness measurements. The methodology encapsulates data collection, signal processing, and interpretation techniques, including the use of local frequency attributes tailored for historical masonry structures. The main perimeter wall at the Circus of Maxentius, Rome, Italy, is used as the case study. The results indicate that GPR is capable of accurately estimating the thickness of Roman stone masonry walls. By conducting a comparative analysis against a wall section with a known thickness, it has been demonstrated that GPR is a dependable and precise method for conducting archaeological and architectural research. This study highlights the potential of using GPR attributes as a non-destructive investigative methodology in the field of heritage preservation. Future research includes extracting and improving further attributes and applying this approach to other historical structures.

Behavior of grout injected solid stone masonry walls under in-plane loading

It is a shared duty of all humanity to ensure the preservation of historical structures for future generations. The discontinuities, cracks, and gaps in the masonry walls, especially in historical structures, prevent the building from working monolithically. For this reason, historical buildings need repair and strengthening efforts in time. Grouting is an effective technique for consolidating and strengthening masonry structures. This study aims to establish a general evaluation of the injection method used to repair damaged stone walls. For this purpose, solid stone masonry walls were constructed and tested under in-plane loading to simulate the actual conditions. The solid stone masonry walls are made of saw-cut travertine stones and plastered with English bond, a pattern formed by laying alternate courses of stretchers and headers. The mechanical behavior of the solid stone masonry walls, both in non-damaged condition and with grout injected into the cracks caused by the preloading, was monitored and demonstrated in terms of the load-displacement relationship. As a result of the wall tests, it was observed that there was an increase of up to 28% in the maximum lateral load that the walls can withstand without any crack formation after grout injection.

A new method of seismic strengthening stone masonry with CRM coatings on one side

The paper presents the results of a research study aimed at assessing the effectiveness of composite-reinforced mortar (CRM) for the seismic strengthening of existing stone masonry walls. The experimental research focused on the strengthening performance of a coating applied only on one side of the masonry wall. Such an application is interesting because it does not require the temporary relocation of residents. The historic two-wythe stone masonry used in the research represents Adriatic’s coastal and surrounding regions. The coating was made of hydraulic lime mortar reinforced with a glass fibre–reinforced polymer mesh attached to the wall using two types of anchors. In-plane cyclic shear compression tests and cyclic out-of-plane tests were conducted, and the performances of the coating on one and both sides were compared. The results showed that the coating on one side was effective, improving all aspects of the seismic response, which was successfully simulated using existing design models.

Flexural Strengthening of Stone Masonry Walls Using Textile-Reinforced Sarooj Mortar.

The majority of historical buildings and structures in Oman were built using unreinforced stone masonry. These structures have deteriorated due to ageing of materials, environmental degradation, and lack of maintenance. This research investigates the physical, chemical, and mechanical properties of local building materials and the results of an experimental study on the out-of-plane bending effectiveness of an innovative strengthening method applied to existing masonry walls. The technique consists of the application of a basalt textile-reinforced sarooj mortar (TRM) on one face of the walls. Bending tests of masonry wall samples (1000 mm width, 2000 mm height, and 350 mm depth) were carried out on one unreinforced specimen and three different cases of reinforced specimens. The performance of unreinforced and reinforced specimens was analyzed and compared. The strengthened specimens were able to resist moments of out-of-plane bending 2.5 to 3 times greater than those of unreinforced specimen (160-233% increase). Moreover, the strengthened walls were able to sustain higher deformations (deflections) than the unreinforced specimen ranging from 20 to 130%. The results showed that using TRM was effective for the out-of-plane strengthening of stone masonry using a local material (sarooj) that is compatible with existing stone masonry building materials.

Geometrical digital twins of the as-built microstructure of three-leaf stone masonry walls with laser scanning

Research on irregular stone masonry walls is hampered by the lack of detailed geometrical models of their internal micro-structure, i.e. the shape and size of each stone and its position within the wall. Without such a geometric digital twin of walls tested in the laboratory, it is difficult to evaluate the accuracy of existing numerical simulation techniques. Here, we describe the generation of geometrical digital twins of three irregular stone masonry walls built in the laboratory. We labelled each stone manually and then obtained the geometry of the individual stones using a portable laser scanning device. With the same device we scanned the wall after the construction of each layer. We then registered the position of each stone in the layer. This paper outlines the methodology for the data acquisition and digital reconstruction and presents the datasets for the walls. The developed geometrical digital twins provide unique information regarding the micro-structure of constructed walls that is key for the development and validation of numerical simulation techniques for stone masonry.