Historical Masonry Research Articles

Behavior of unreinforced multi-leaf stone masonry walls under axial compression: Experimental and numerical investigation

This paper presents an experimental and numerical investigation on the behavior and failure mechanisms of unreinforced multi-leaf masonry walls. The main objective of this study is to explore the propagation of cracking, ultimate load, and deformation characteristics of different typologies of three-leaf walls commonly found in historic masonry. Axial compression tests on scaled three-leaf wallettes built of limestone units and lime-based mortar, as well as experiments on constituent materials for each leaf, were carried out. The main results obtained from the experimental tests are the mechanical characteristics, stress–strain curves, stress distributions in multi-leaf masonry walls. The research findings elucidate a strong correlation between the bearing capacity of multi-leaf walls and the thickness ratio of the inner-core layer to the external layers. This relationship underscores the critical significance of the inner-core layer in efficiently carrying the applied vertical loads. Furthermore, the extent to which the inner-core layer actively contributes to load-bearing is contingent upon the interconnectivity among the three layers. Walls with keyed collar joints have a higher strength and stiffness than the walls without transverse tying, with the strength being comparatively higher by about 9–13 %. This clarifies the contribution of the inner core layer and that of the two outer layers in resisting vertical loads and enhancing the overall composite behavior of the wall. Finally, these results allow for validating non-linear numerical procedures based on two-dimensional plane strain modelling along wall thickness and a simplified micro-modelling approach, which prove to be adequate tools for detailed modelling of masonry components of similar nature.

Experimental collapse investigation and nonlinear modeling of a single-span stone masonry arch bridge

Determining appropriate intervention methods for rehabilitation and restoration of historic masonry bridges requires understanding the true behavior of the structural system. The presented study addresses this need by focusing on nonlinear structural behavior of stone masonry arch bridges and investigates the effect of different constitutive material laws, modeling approaches, and multiple spans on simulating the true behavior of the structural system. An extensive experimental program was conducted on a ¼-scaled model of a selected span of the multi-span arch bridge consisting of the arch ring, spandrel walls, and the fill. The model was tested with and without the presence of an in-plane steel bracing system supporting the spandrel walls to study the effect of adjacent spans on the selected span. Line loading applied at the quarter-span was increased with constant increments until. Destructive experimental investigation was followed by numerical studies of the tested specimen by means of both macro and simplified micro modeling approaches with DIANA FEA software utilizing different constitutive material models including Multi-Directional Fixed Crack Model with/without Drucker-Prager plasticity material law and Total Strain Based Fixed Crack Model. Comparison of the experimentally measured values with those of the numerical model validates that both modeling approaches can accurately predict the collapse load and collapse mechanism. Although simplified micro model offers advantages such as capturing the observed local damage states and cracking at masonry joints between the units; the added requirements of time, computational effort, and detailed material knowledge to model such structures accurately, makes macro modeling technique more preferable for masonry bridges having a complex geometry.

Investigation of GRC Retrofitting Effect on Masonry Dome Using FEM

Historical buildings are the cultural heritage of the world. Preservation of historical buildings is important in the past and today. In particular, material fatigue, environmental vibration effects and natural disasters that occur over time cause great damage to historical structures. It is thought that many historical buildings will not reach the next years due to neglect. In order to prevent this situation, historical buildings should be maintained and strengthened if necessary. In addition, historical buildings should have sufficient stiffness to prevent collapse against pre-disaster situations. Masonry domes are often seen in historical buildings. Many masonries dome historical structures are frequently encountered today. In order for masonry dome in historical building to be transferred to the future, care should be taken and they may need to be strengthened periodically, especially after disasters. For all these reasons, in this study, the GRC retrofitting method, which is one of the retrofitting methods of buildings, is mentioned. Thus, the effect of the GRC retrofitting method applied on an exemplary historical masonry dome on modal parameters has been demonstrated. In this comparative study, it was observed that the stiffness of the masonry dome increased with the GRC retrofitting method. As a result of this study, it is suggested to retrofitting masonry dome with the GRC retrofitting method, taking into account the state of the historical building and environmental factors.

Structural morphology and seismic evaluation of intersecting masonry space structure (Karbandi system)

Research into the historical masonry buildings of the city of Tabriz have resulted in determining the fundamental features of some important masonry structural systems. These features include architectural and structural morphologies, force flow/management in the structures, and understanding the interplay of different structural elements. In this paper, these features are assessed by analyzing the structural response of the Haj Mohammad-Qoli Timche in the Tabriz Bazaar, a registered UNESCO World Heritage site. This study was carried out in three main stages. First, the architectural and structural morphologies of the Timche were investigated. The results demonstrated that Karbandi is a highly-efficient structural system in the construction of arched historical buildings. Thereafter, two scaled experimental models of the Haj Mohammad-Qoli Timche were constructed to perform experimental and numerical evaluations. A suitable agreement exists between the numerical and experimental results, to the point that the frequency error percentages for the first and second specimens are equal to 0.5% and less than 1%, respectively. Finally, the seismic behavior of the structure was assessed using Incremental Dynamic Analyses. The results indicated that due to collapse initiating at higher stress intensities, the Karbandi is a suitable structural system capable of withstanding seismic loads. The results also revealed that the arch intersection points eliminate the tension regions, thereby improving the seismic behavior of the Karbandi. Buttress elements were added to the structure during the restoration of the Timche as a seismic enhancement measure.

Seismic assessment and strengthening of a historical masonry bridge considering soil-structure interaction

A holistic methodology for developing the digital twins and conducting seismic vulnerability assessments of masonry arch bridges is proposed and applied to a historical stone masonry bridge. In this light, digital cameras, drones, and 3D laser scanners were utilized for 3D geometric documentation of the bridge. 3D finite element (FE) models were constructed and calibrated based on the operational modal analysis results derived from the accelerometer sensors. The fragility curves for different limit states were derived by performing a multi-stripe analysis (MSA). The effect of soil-structure interaction (SSI) on the calibration results and seismic response of the bridge was evaluated. The results of the visual inspection, model calibration, and seismic analysis revealed that the central pier and the arches are the most susceptible parts of the bridge. Therefore, three strengthening techniques were proposed, and corresponding numerical models were developed. The first model was developed by enhancing the mechanical properties of the vulnerable parts of the bridge, and the two other models were built by covering the central pier’s outer surface with polyparaphenylene benzobisoxazole (PBO) and carbon fiber-reinforced concrete mortar (FRCM) layers. Results revealed that the strengthening techniques improved the seismic response of the bridge when subjected to transverse seismic excitations. Negligible differences in the displacement response and crack width of the strengthened models were observed from the nonlinear dynamic analysis.

Post-earthquake assessment of monumental building in Croatia by 3Muri software

Abstract. A series of earthquakes in and close to city of Zagreb, Croatia during the 2020 severely damaged the masonry cultural heritage buildings built in the 19th century. The article presents the assessment of post-earthquake design of retrofitting of damaged historic masonry structure of the former synagogue in city of Sisak, Croatia erected in 1890. The former synagogue was severely damaged during the recent earthquake. For the purposes of the post-earthquake retrofitting and strengthening, an analysis of the damaged and retrofitted structure has been carried out to justify the selected retrofitting measures that included a partial reconstruction of heavily damaged structure. The equivalent frame model based on the discretization in terms of piers and spandrels was created (SEM - Structural Elements Model) to obtain the simulation of earthquake response of structure using the 3Muri 13.9 software. In this paper the procedure and results of the analysis of seismic resistance of the strengthened structure is presented because of the successful cooperation of structural engineers, architects and conservators.

Seismic Analysis of Historical Masonry Towers with Different Support Conditions

ABSTRACT In this paper, a series of incremental dynamic analyses were performed on five masonry towers resting on the base, whose geometry was taken from the literature, in order to determine how the difference in geometric characteristics and deformability of the subsoil affect the global behaviour, failure mechanism and seismic resistance of the towers. Special attention was attributed to determining whether masonry towers experience rocking motion mechanism during seismic excitation, which proved to be suitable in terms of seismic energy dissipation and earthquake resistance. Analyses were carried out using the planar numerical model based on the Combined Finite-Discrete Element Method (FDEM) at the macro level. The conclusions obtained on the basis of the conducted analyses can serve the researchers as guidelines to gain an insight into the expected failure mechanism of masonry towers for the assessment of their seismic resistance, as well as for making decisions about actions during their rehabilitation.

Experimental investigation of the behaviour of injection anchors in rubble stone masonry

The seismic response of historical masonry buildings is largely controlled by the effectiveness of wall-to-diaphragm connections, which can be improved using injection anchors. Despite their use, there is a need for a better understanding of the performance of such anchoring system in stone masonry walls. This paper presents quasi-static pull-out tests performed on twelve specimens to investigate the behaviour of injection anchors in rubble stone masonry walls when breakout failure occurs. For each specimen, the experimental results are presented in terms of force–displacement curves, propagation of damage and crack pattern. It is shown that the anchoring details adopted in this study had a negligible influence on the pull-out force capacity of the anchoring system, while an increase in peak pull-out force was observed with increasing overburden stress applied. Because stone masonry specific capacity formulations have not yet been presented in the literature, the capacity is predicted using state-of-the art formulations for the pull-out load capacity of anchors installed in brick masonry. The limits of their applicability are discussed using the obtained experimental results.

Pore structure and fractal dimension analysis of ancient city wall bricks in China

Comprehensive quantitative characterization of the pore structures of ancient city wall bricks is important for predicting the durability of historical masonry buildings. However, in most previous studies, only one or two methods were used to analyse the pore structures of fired clay bricks. In this study, mercury intrusion porosimetry (MIP), low-temperature nitrogen adsorption (LTNA), and low-field nuclear magnetic resonance (LF-NMR) were used to characterize the pore structure and fractal dimension of nine different ancient city wall bricks. The results show that the surface relaxivity of ancient bricks measured via the Hahn spin echo (HSE) in LF-NMR ranged from 1.55 to 1.75 μm/s. Furthermore, the porosity of the blue bricks measured via LF-NMR were much lower than that obtained via the gravimetric method owing to a higher number of paramagnetic iron mineral phases. LTNA was not suitable for describing pore size distribution of ancient bricks as the pore diameters were mainly concentrated in the range of 100–1000 nm. The pore structures of ancient bricks in dried and water-saturated states were different, the pore size of the white bricks obtained via LF-NMR was smaller than the MIP-derived pore-throat size by a factor of approximately 2.

Structural design and engineering of Striatus, an unreinforced 3D-concrete-printed masonry arch bridge

This paper describes the structural design and engineering of “Striatus”, a 3D-concrete-printed unreinforced masonry pedestrian bridge built in Venice in 2021 as part of the Time Space Existence exhibition organised by the European Cultural Centre. The project combines the latest developments in 3D concrete printing with the structural principles of historic unreinforced masonry. Typically, the structural applications of 3D concrete printing are limited to elements such as columns and walls loaded vertically, perpendicularly to the horizontal printing layers, to formwork elements or secondary structural elements. Indeed, fabrication constraints, delamination issues and the low tensile strength of the concrete have been seen as limiting factors to 3D concrete printing for structural applications demanding resistance to bending or predominant loading directions not perpendicular to the printing layers. By using unreinforced-masonry structural principles, this paper shows that structural elements spanning space horizontally, such as a pedestrian bridge, can be built by using the 3D concrete printing components as the main structure, working only in compression, loaded perpendicularly to the printed layers. Furthermore, as a compression-only structure following masonry principles, Striatus enabled the use of unreinforced concrete without any mechanical or chemical connections between the elements and the separation of concrete and steel, only used for the supports and to equilibrate the horizontal thrust of the arch effect through the tension ties. This work shows how the application of unreinforced masonry principles to 3D concrete printing offers new opportunities in terms of structural design and represents a strategy to increase sustainability by reducing material consumption and allowing reusability and recyclability of the structure. Finally, this paper discusses the critical aspects related to the design of Striatus from an engineering and construction point of view.

The evaluation of the adhesion defects in FRCM reinforcements for masonry constructions by Sideband Peak Count based nonlinear acoustic technique

Fabric-reinforced cementitious matrix (FRCM) composites have emerged as reliable strengthening materials especially for historical masonry constructions. Their strengthening effectiveness strongly depends on the bond at the matrix-fibers interface and at the matrix-substrate interface; thus, the analysis of FRCM bond behavior is of crucial relevance. The strong diffusion of the FRCM composites for the reinforcement of masonry and concrete constructions requires suitable experimental techniques for assessing possible defects in the adhesion between FRCM and masonry, and between FRCM layers. To this aim, in this paper, an innovative nonlinear ultrasonic approach based on the sideband peak count technique is proposed. This approach is discussed and validated through acoustic (sonic and ultrasonic) tests performed on masonry tuff substrates reinforced with FRCM mortars embedding a basalt fibers grid and having known artificial defects at the adhesion between masonry and the reinforcement as well as in the fiber grid.

Investigating the historical building materials with spectroscopic and geophysical methods: A case study of Mardin Castle

Today, the building materials form the historical buildings are being exposed to various deteriorations increasingly due to different causes. Many historical masonry constructions in the world are on the edge of extinction due to the increasing frequency and changing models of material deterioration. The materials as close as possible to the original materials in terms of their chemical compositions and physical properties are required in the reconstruction and maintenance of the buildings that have historical importance. In addition, the properties of the materials used in the historical buildings are generally not known with a sufficient accuracy. This causes misapplications in case of emergencies, and also may lead to future potential greater damages on the building. The lack of data regarding the engineering properties of these buildings causes long-term damages on the buildings due to inappropriate conservation methods and materials. Therefore, it is necessary to investigate the properties of certain materials for application in the renewal of the historical buildings. Within this context, in this study the construction materials of Mardin Castle, which is located in Mardin Province, Turkey and existing for centuries as the symbol of the city, are investigated and its properties are reached. Experimental research methods were used in the study. Primarily, the castle structure was examined on-site by field study and sampling was carried out from the areas determined. The samples were analyzed via various spectroscopic and geophysical methods, and various findings were achieved. Relatively variable and high levels of salinization were determined in the findings regarding the average values in stone samples of Mardin Castle’s Fortification Walls. Results of the research document the conservation status regarding Mardin Castle and provide an experimental base and also a theoretical support for the conservation of historical buildings in Turkey; and present indicative suggestions to establish conservation schemes of the historical buildings.

Investigating of the Reasons for the Collapse on the Entrance Arches of the Harran Grand Mosque (Ulu Cami) During the Kahramanmaraş Earthquakes (Mw 7.7 and Mw 7.6)

Although historical masonry structures are highly aesthetic, they harbor numerous structural uncertainties. These structures encompass information such as the date of construction, construction methods, material properties, design details and more. They possess diverse identities in various aspects, making the structural assessment of historical buildings a challenging task. Consequently, all historical buildings should be treated with special consideration, and suitable solutions must be devised. In this study, the structural damage causes of the entrance gate of the Harran Grand Mosque (Ulu Cami), which had undergone recent restoration but suffered damage once again during the Kahramanmaraş earthquakes on 6 February 2023 have been investigated. A three-dimensional finite element model of the structure was developed using Abaqus software. In the numerical studies the static as well as non-linear dynamic earthquake analyses were conducted to evaluate the reasons of the collapse of the structure. The structure was subjected to earthquakes from different directions and its compatibility with actual damage scenarios was observed. The study results are presented with contour diagrams of displacement, stress and damage situations. Upon reviewing the numerical findings obtained from the study, it is evident that the actual damage condition of the structure can be reasonably simulated. As a result, it is thought that the earthquake hit the entrance arches from out of plane which caused the collapse. To sum up, by evaluating the damage conditions resulting from such numerical studies, restoration applications can be handled more effectively, ensuring that correct interventions are carried out.

Automated image-based generation of finite element models for masonry buildings

To predict the response of masonry buildings to various types of loads, engineers use finite element models, specifically solid-element and macro-element models. For predicting masonry responses to seismic events in particular, equivalent frame models—a subcategory of macro-element models—are a common choice because of their low computational cost. However, an existing bottleneck in modeling pipelines is generating the geometry of the model, which is currently a slow and laborious process that is done manually using computer-aided design tools. In this paper, we address this by automating the modelling process using recent advancements in computer vision and machine learning. We present an image-based end-to-end pipeline that automatically generates finite element meshes for solid-element and equivalent-frame models of the outer walls of free-standing historical masonry buildings. As the input, our framework requires RGB images of the buildings that are processed using structure-from-motion algorithms, which create 3D geometries, and convolutional neural networks, which segment the openings and their corners. These layers are then combined to generate level of detail models. We tested our pipeline on structures with irregular surface geometries and opening layouts. While generating the solid element mesh from the level of detail model is straightforward, generating equivalent frame models required algorithms for segmenting the façade and the meshing. Experts in the field analyzed the generated equivalent frame models and determined them to be useful for numerical modeling. These finite element geometries will be invaluable for future predictions of the seismic response of damaged and undamaged buildings. The codes and dataset are publicly available for future studies and benchmarking (https://github.com/eesd-epfl/FEM_buildings and https://doi.org/10.5281/zenodo.8094306).

Quantification of Moisture in Masonry via AI-Evaluated Broadband Radar Reflectometry

Humidity, salt content, and migration in building materials lead to weathering and are a common challenge. To understand damage phenomena and select the right conservation treatments, knowledge on both the amount and distribution of moisture and salt load in the masonry is crucial. It was shown that commercial portable devices addressing moisture are often limited by the mutual interference of these values. This can be improved by exploiting broadband radar reflectometry for the quantification of humidity in historic masonry. Due to the above-mentioned limitations, today’s gold standard for evaluating the moisture content in historic buildings is still conducted by taking drilling samples with a subsequent evaluation in a specially designed laboratory, the so-called Darr method. In this paper, a new broadband frequency approach in the range between 0.4 and 6 GHz with improved artificial-intelligence data analysis makes sure to optimize the reflected signal, simplify the evaluation of the generated data, and minimise the effects of variables such as salt contamination that influence the permittivity. In this way, the amount of water could be determined independently from the salt content in the material and an estimate of the salt load. With new machine learning algorithms, the analysis of the permittivity is improved and can be made accessible for everyday use on building sites with minimal intervention by the user. These algorithms were trained with generated data from different drying studies on single building bricks from the masonries. The findings from the laboratory studies were then validated and evaluated on real historic buildings at real construction sites. Thus, the paper shows a spatially resolved and salt-independent measurement system for determining building moisture.

DEGRADATION OF HISTORIC MASONRY BY ANALYTICAL AND DIGITAL PHOTOGRAMMETRY: A QUANTITATIVE ANALYSIS

Abstract. The degradation of Cultural Heritage sites is one of the biggest challenges in modern societies and it is becoming a pressing issue in many countries. Our Cultural Heritage is degrading faster today than any time in the past. Countries as Italy, boast a significant part of the heritage buildings and structures all over the world, typically made of stone. These countries are increasingly challenged to properly maintain their important legacy while keeping maintenance low-costs for the preservation. The degradation of historic masonry structures can be manifested in different ways that can be focused from different perspectives and disciplines. The present study-case deals with the Ponari Nymphaeum, a Roman building dated to the 1st century B.C., that has been the object of a study begun in 2010. The site is located on the slopes of Montecassino, in the Southern Lazio and it has been the object of a survey and monitoring begun in 2010, and updated to 2019, aimed at documenting the structural and architectural degradation of the site due to the negligence and the climate change by using the combined approach of the analytical and digital photogrammetry.The results show the efficiency of the proposed methodology to identify not only the existing state of degradation of the site, but also a useful approach to preserve and to reconstruct the missing and damaged parts that can be reproducted with high accuracy.

ELŻBIETA DĄMBSKA-ŚMIAŁOWSKA (1924-2021); ARCHITEKT, BADACZ I DYDAKTYK

Elżbieta Dąmbska-Śmiałowska graduated from and worked at the Cracow University of Technology. Apart from teaching General Building Construction and Material Science courses, she conducted research on historical wooden and masonry buildings. She was a humanist shaped by Eastern Borderlands culture, familial tradition and the experience of the Second World War. Underground education, including university education, became the foundation of her studies in the Kraków School of architecture, her academic work and post of vice dean. Her research was conducted in a team of dedicated co-workers and doctoral candidates.

Seismic failure modes of masonry structures exposed to Kahramanmaraş earthquakes (Mw 7.7 and 7.6) on February 6, 2023

In this study, the failure modes of masonry structures after the earthquakes (Mw 7.7 and 7.6) occurred in Kahramanmaraş on February 6, 2023 were investigated by fieldwork. Within the scope of the study, information of the building stock in Türkiye and the Middle East countries was given, and a literature regarding the major failure modes in masonry structures was mentioned. The characteristics of the ground acceleration and earthquake parameters measured during the earthquake were presented. Damage distributions in historic masonry structures and masonry dwellings were examined. In addition to the out-of-plane behavior which is the most common failure mechanism in masonry structures, the corner failure mechanism has been also observed in many masonry buildings. It has been determined that the corner failure mechanism is triggered by the combination of the in-plane and out-of-plane failure behaviors. In this manner, the observed damages were classified as in-plane, out-of-plane, and corner failures. It has been determined that damaged masonry structures are mostly out of use with out-of-plane and corner failure mechanisms. These two failure mechanisms were directly related to inadequate wall-roof and wall-floor connections, insufficient axial load, low material strength, poor workmanship, and the lack of engineering service. In-plane failure mechanisms are triggered by irregular door and window openings exceeding the limits given in the regulations. In addition, it has been revealed that many masonry buildings do not have adequate vertical and horizontal lintel band to increase the lateral seismic performance of the walls. In the last part of the study, the advantages and disadvantages of the strengthening methods that can be used in masonry structures with light and moderate damage were examined, and some suggestions were made.

Earthquake response and damage patterns assessment of two historical masonry churches with bell tower

The earthquake response of two historical masonry churches is investigated through a finite element macro-modelling approach and non-linear dynamic analyses. The main aim of the study is to evaluate the church walls effects on the seismic performance and damage patterns of slender bell towers, which are analyzed also in the isolated configuration to perform a comprehensive comparison with the confined counterpart. The results of the numerical simulations point out that both the churches, which present different sizes, structural features and dynamic properties, are highly vulnerable to low-to-moderate seismic actions and the bell tower is one of the most critical elements, suffering widespread damage due to also the interactions effects with the neighboring church walls. The presence of shorter adjacent structural elements significantly modifies the main structural dynamic characteristics, seismic response and damage patterns of the bell tower. For both the confined towers, the first cracks originate in the connection regions with the adjacent church walls: on the other hand, for both the isolated towers, the first cracks originate mainly at the base. An advance of damage onset is also detected in the case of confined towers with respect to isolated towers. At the end of the numerical analyses, for both the case studies, the confined configurations show more remarkable damage patterns and larger values of energy density dissipated by tensile damage than the isolated ones, presenting relevant cracks concentrations mostly near the connection regions with the church walls and in the middle-upper part of the bell tower. The results of this study emphasize the paramount importance of taking into account the interactions effects with the surrounding church walls for a proper damage and failure mechanisms assessment of bell towers within the church context: simplified analyses performed on isolated configurations without considering such interaction effects may lead to significant underestimations of damage for the bell tower inside the church.

Freeze-thaw resistance of pozzolanic hydrated lime mortars

Degradation of hydrated lime mortars subjected to freezing and thawing is common in historic building conservation. The pozzolanic additions, Argical M1000, diatomite (diatomaceous earth) and brick dust, were evaluated for their ability to improve performance for up to 720 days. Pozzolanic reactions influenced the pore structure evolution, mechanical performance, and chemical reactivity of the mortar matrix. Argical-lime mortars exhibited a sudden failure, while a gradual reduction in mechanical strength was observed for mortars containing brick dust. A slower rate of failure in diatomite mortars was attributed to pore refinement, which was associated with superior freeze thaw performance. This study has advanced the current state of the art regarding how pore structure affects lime mortars' freeze and thaw resistance. Therefore it provides spesifications on how to optimise mortars for historic masonry. A key impact is the more effective use of lime mortars for conservation, thereby protecting heritage structures from degredation.