Ancient Masonry Structures Research Articles

Study on the shear properties of masonry pagoda mortar and its influencing factors

Mortar stands as one of the fundamental components in masonry construction, significantly enriching the global cultural heritage, particularly evident in ancient masonry structures. In this paper, the improvements of shear strength of mortar were studied, based on the original formulation material of sticky-rice lime mortar. The study considered the effect of different aggregates and additives on the shear strength of mortar, the shear tests and scanning electron microscopy were employed to analyze the shear strength index and microscopic shear basis of the mortar. The results showed that 2 wt% Na-SiO2 significantly enhanced the shear strength of the mortar. Furthermore, the adhesion and frictional resistance between fiber and lime played a crucial role in enhancing the mortar's shear resistance. Incorporating a 0.5 wt% fiber additive not only effectively improved the mortar's brittleness but also acted as a deterrent to crack formation. Compared to pure lime mortar, the mixture of sand and clay aggregate exhibited a larger capacity at the same volume. This mortar also showcased better plasticity and ductility, making it more suitable for structures with significant shear deformation. These analytical findings provide valuable insights for modifying mortars in the restoration of historical buildings.

Analysis of Chinese ancient brick masonry characteristics under uniaxial compression fatigue loading

Urban expansion and diversified traffic aggravate the damage and deterioration of ancient buildings. It is crucial to evaluate the long-term fatigue performance of ancient brick masonry structures for the safety and maintenance of ancient buildings. A series of indoor tests were conducted on the ancient brick masonry. The images for the whole process of the test were collected using VIC-3D technology. The relationship between the stress level and the number of failure cycles under compressive fatigue load and the stress–strain evolution under different stress levels were determined. A mathematical model of p-S-N fatigue life prediction based on probability was proposed, which comprehensively considered the maximum stress level, stress range, number of load cycles, and survival probability. The equivalent fatigue life of ancient brick masonry specimens under each failure probability obeys Weibull distribution, and then the fatigue life of masonry can be predicted at any expected confidence level. The test results provide reliable theoretical and data support for fatigue deterioration and life prediction of ancient masonry structures in service.

Advanced numerical insights for an effective seismic assessment of historical masonry aggregates

The structural assessment of ancient masonry structures is still a challenging task. The main reasons have been related to the shortage of information in the materials’ characterization along with the complex geometry and different evolutions of its constituents’ parts through the time. Scientific studies on the evaluation of the structural capacity and design of these masonry buildings have reported several modelling techniques. The goal of this work is to investigate the effectiveness of different numerical approaches in the simulation of the cyclic behaviour of historic masonry buildings under seismic loads. In addition, the damage level of the structural interconnections will be evaluated and what extent they affect the global instability. The specific case study seeks to examine an ancient palace with its civic tower hit by the 2016 Central Italy earthquake. A couple of masonry modelling are used: the first one is discontinuous (DM) and the second one is continuous (CM). Two models were set: one model replicated the structure as a whole, the other one considered only the tower. The DMs were studied with 3DEC© and LMGC90© software, where, in turn, different contact conditions were implemented. In parallel, the CMs were analysed with the Midas FEA NX©. The present research offers significant outcomes obtained from the non-linear dynamic analyses performed using the proper sequence recorded in that seismic event. Likewise, this document underlines the importance of the correct modelling techniques definition, based on the state of the case study, especially when an isolated tower is considered.

Experimental investigation of the deformability of the masonry vault in church historical building

Masonry is a dominant material in historic buildings of architectural heritage. The investigation of masonry structures faces an issue of building a numerical model in engineering software systems, considering the question of studying ancient masonry, which is technologically different from the modern one. At the same time, vaults were extensively used in majority of types of roofing systems of historic buildings. The study area covers the mechanical properties of ancient masonry vaulted structure and ways of testing ancient brick samples to determine its more accurate behaviour and receive the information related to the deformability of such a complex structure. The main aim of this article is the survey of the masonry cloister vault of the historical building in order to receive the data on the specific deformation characteristics of the ancient masonry materials. Methods of the determination of the deformation properties of a masonry proposed in the building codes has uncertainties because it neglects the special aspects of the historic masonry. Thus, the need for conducting full-scale physical and numerical experiments of the masonry vault in church historical building for obtaining the actual data on the deformability of the ancient masonry structure appears urgent. Additionally, the experimental part of the research work on the object was carried out in two statements of the problem: the object was studied from the point of view of a homogeneous structure, videlicet the study of the vault itself was carried out, as well as a heterogeneous structure, in which the masonry elements (mortar and brick) were studied separately. The evaluation of data related to such structures is extremely important for the improvement of restoration techniques, maintaining and preventing possible critical situations associated with them. Moreover, the received data will allow to make adjustments in calculations considering the peculiar properties of material.

Effectiveness of Flax-TRM composites under traction

The scientific research in the field of masonry structures is increasingly welcoming the adoption of innovative and sustainable rehabilitation techniques aimed at the safeguarding of the Built Cultural Heritage. Textile Reinforced Matrix (TRM) composites are the most widely investigated strengthening systems for ancient masonry structures, thanks to their high compatibility level with the material substrates in terms of fire resistance, chemical/physical aspects, reversibility property, little impact on dimensions, stiffness and weight. Nevertheless, in the last years, the growing concern on sustainability increased the interest in products with low environmental impact, for promoting circular economy approaches in the design of the structural interventions. In particular, efforts have been done to replace the most common composites with materials less harmful to the environment, such as natural fibres, for developing compatible and sustainable rehabilitation techniques for masonry structures. This paper presents the preliminary results of experimental tests conducted by the authors on specimens of TRM composites made with natural, vegetable, flax-fibre grids and natural hydraulic lime mortar. The mechanical characterization tests aimed at detecting the tensile behaviour of the natural TRM system compared to the results available in the literature on different vegetable-fibre composites and TRMs made with natural basalt fibres. The experimental tests highlighted the promising mechanical effectiveness of natural TRM systems under traction and offered a hint to further research aimed at improving their mechanical strength and stiffness.

An Overview of the Historical Retrofitting Interventions on Churches in Central Italy

The seismic sequence occurring in Central Italy in 2016 represents a new test benchmark for historical masonry churches and a chance for a better comprehension of their structural behavior under earthquake actions. The many earthquakes that took place in the past have led to stratifications of repair and retrofitting interventions that sometimes worsened the structural behavior, especially when resulting in the introduction of elements not compatible with the churches’ original layout. Within this framework, the present paper intends to provide a critical review of the main interventions carried out in the churches of Central Italy for mitigating their seismic vulnerability and to evaluate their effectiveness in light of the damage surveyed on a representative sample of masonry churches after the 2016–2017 seismic sequence. The work is organized into three parts: (1) historical analysis of the territory; (2) review of the featured interventions; (3) critical appraisal of the interventions in relation to the surveyed data and assessment of their effectiveness. The goal of the work is to shed light on the correct design of retrofitting interventions in ancient masonry structures in order to enhance the structural safety of such artefacts without compromising their historical and cultural value.

Structural and seismic vulnerability assessment of the Santa Maria Assunta Cathedral in Catanzaro (Italy): classical and advanced approaches for the analysis of local and global failure mechanisms

The evaluation of the seismic vulnerability of existing buildings is becoming very significant nowadays, especially for ancient masonry structures, that represent the cultural and historical heritage of our countries. In this research, the Cathedral of Santa Maria Assunta in Catanzaro (Italy) is analyzed to evaluate its structural response. The main physical properties of the constituent materials were deduced from an extensive diagnostic campaign, while the structural geometry and the construction details were derived from an accurate 3D laser scanner survey. A global dynamic analysis, based on the design response spectrum, is performed on a finite element model for studying the seismic response of the structure. Moreover, a local analysis is conducted to evaluate the safety factors corresponding to potential failure mechanisms along preassigned failure surfaces. Furthermore, pushover analyses are performed on macro-elements, properly extracted from the whole structure and with an independent behavior with regard to seismic actions. A novel model based on inter-element fracture approach is used for the material nonlinearity and its results are compared with a well-known classical damage model in order to point out the capability of the method. Finally, the results obtained with the three different models are compared in terms of seismic vulnerability indicators.

Postseismic Survey of a Historic Masonry Tower and Monitoring of Its Dynamic Behavior in the Aftermath of Le Teil Earthquake (Ardèche, France)

ABSTRACTOn 11 November 2019, an Mw 4.9 earthquake struck the middle Rhône valley (South-East France) producing moderate to severe damage in the town of Le Teil and its surroundings. This unexpected event stressed the vulnerability of the French cultural built heritage to a moderate seismic hazard. Commonly applied to modern civil engineering structures, passive seismic methods are still lacking on historic constructions to understand properly the different factors driving their dynamic behavior. In this article, the results of a two-month seismic monitoring survey carried out shortly after the Le Teil mainshock in a historic masonry tower are presented and discussed. Located only 5 km south of the epicenter, the Gate Tower of Viviers (eleventh century) was instrumented with four highly sensitive seismic nodes. Ambient vibrations, as well as aftershocks and quarry blasts from the nearby Le Teil quarry, were recorded and used in the analysis. Through vibration-based analysis, the article addresses three relevant aspects of the dynamic response of ancient masonry structures. We discuss first the differences in the building’s response induced by the three reported types of vibrations, focusing on the particular signal characteristics of shallow aftershocks and quarry blasts. Then, we apply the Random Decrement Technique (RDT) to track the dynamic behavior variations over two months and to discuss the role of the environmental conditions in the slight fluctuations of the structural modal parameters (natural frequencies, damping coefficients) of unreinforced masonry structures. We also show evidence of the nonlinear elastic behavior under both weak seismic and atmospheric loadings. The correlation between the presence of heterogeneities in the construction materials and the nonlinear threshold supports the relevance of such types of monitoring surveys as a valuable tool for future modeling works and conservation efforts.

Investigation of compression constitutive relationship of ancient brick masonry

Through uniaxial compressive strength tests on glutinous rice mortar, ancient bricks, and ancient brick masonry, the main mechanical properties of ancient masonry materials and the stress–strain relationship of ancient brick masonry were analyzed under uniaxial compression. Based on the compressive strength of the masonry, compressive strength of a single brick, and compressive strength of the mortar, the constitutive relationship of the ancient brick masonry in the Shanxi Province of China and the formulas for elastic modulus was established. The results reveal that the constitutive relationship of masonry under axial compression can satisfactorily fit the experimental data obtained for masonry under axial compression. The model provides a theoretical basis for the finite element simulation and durability evaluation of ancient masonry structures in the Shanxi Province of China.

Influence of Stereotomy on Discrete Approaches Applied to an Ancient Church in Muccia, Italy

This work evaluated the remarkable influence of stereotomy on discrete methods adopted for the dynamic response of an ancient masonry structure. The historic building used as a case study is the Church of Santa Maria of Varano in Muccia, in the province of Macerata, Italy, which was exposed to the severe seismic sequence that hit Central Italy in 2016, namely the major events of Accumoli, Visso, and Norcia. The structure was modeled using the actual stereotomy of blocks and three hypothetical arrangements of blocks of the masonry walls to investigate the existing crack pattern and vulnerabilities of the church. Sensitivity analyses were performed using the nonsmooth contact dynamics and discrete-element methods. These novel approaches suitably reproduced complex behaviors, considering large displacements and complete block separations, which is useful for upcoming retrofitting works.

Structural Assessment of Ancient Masonry Structures: An Experimental Investigation on Rubble Stone Masonry

ABSTRACT Non-destructive investigation procedures are appropriate approaches for the qualitative mechanical assessment of heritage masonry structures. This study aims to contribute to the knowledge of one of the most common ancient masonry typologies, particularly in Roman archaeological sites, the rubble stone masonry, that is the ancient opus incertum, with an extensive experimental program carried out in the archaeological site of Pompeii. The research focused on archaeological masonry structures with different states of preservation and with or without modern interventions. A non-destructive investigation procedure was carried out including detailed geometrical and material surveys, visual inspections and an extensive program of sonic pulse velocity tests, with a total of 1965 acquired velocities. The paper describes the adopted investigation protocol and detailed analysis and discusses the experimental outcomes. Comparisons with available literature data concerning different masonry typologies at the Pompeii site are also presented. Furthermore, the results of the non-destructive investigation have been compared with available mechanical information from destructive and non-destructive tests performed by the authors on Pompeii-like masonry panels. The unique set of data collected may represent a sound tool for the estimation of the mechanical parameters of the ancient masonry structures, which is a crucial step for the definition of preservation actions.

Experimental analysis of lime putty and pozzolan-based mortar for interventions in archaeological sites

The study aims at defining and characterizing a specific restoration mortar for archaeological masonry structures made with traditional materials and to assess the suitability of the mixture compared to other mortars; such a goal is crucial to develop and define interventions in the archaeological sites. The mixture was defined to ensure compatibility with ancient materials and following frequently adopted recommendations at the site, specifically by using: (1) raw materials as similar as possible to the ancient ones; (2) traditional mix design. Therefore, the mixture was made with commercial lime putty CL 90-S type and natural Phlegrean pozzolan, i.e. volcanoclastic material collected from the volcanic area located in the West of Naples in Italy. The precious and limitedly available natural pozzolan used in the experiments resulted in an exclusive mortar which is very similar to the archaeological ones. The mortar has a binder to aggregate ratio 1:3 by volume, according to traditional techniques typically encountered in the ancient Roman city of Pompeii and Vesuvius surrounding area. The evolution of the flexural and compressive strength, elastic modulus, bulk density, open porosity and ultrasonic pulse velocity has been monitored for up to 200 days, based on standard procedures. Moreover, the hardening process was monitored with Differential Thermal Analysis up to 90 days, through the evaluation of phase transitions associated with dehydroxylation and decarboxylation, considering different depths from the external surface of the mortar. The achieved mechanical properties were compatible with those of lime-based mixtures for repair interventions of ancient masonry structures. Moreover, the mortar was found to be well-suited to mitigate cracking, showing a low ratio between its stiffness and load capacity compared to other typologies of mortars used for masonry restoration. Ultrasonic pulse velocity test proved to be a reasonable complementary method to monitor the evolution of the hardened properties of the mortar. Carbonation was found to be still progressing at 90 days. The data presented provide useful and reliable information to approach the complex process of restoration in archeological sites.

Performance of single and double flat jacks in stone masonry lab tests

At inspection and diagnostic phases of ancient masonry structures, it is often necessary to evaluate the compressive strength and stiffness of stone masonry of masonry walls. These walls are a heterogenous material, and the number of in-situ test methods is limited, being the flat jack tests the most used ones. Besides other uncertainties in the accuracy of the results obtained with flat jack tests, they are frequently used to estimate the mechanical characteristics of ancient building's walls.In this paper, results from an experimental campaign are presented and discussed, carried out on a large scale specimen built with limestone masonry and natural hydraulic lime, with the aim of comparing the stress level obtained with the single flat jack test with the real stress.Various recommendations are put forward, regarding the use of this methodology in masonry walls, for validation and determination of the in-situ compressive stress level.Furthermore, test results of double flat jack tests are presented, and a comparison is made between the specimen's compressive strength, obtained through the double flat jack test and the axial compression test, having obtained relatively close values.All results are compared with the ones of other authors and several conclusions are presented.

Stability of Treatment from Earth-Based Mortar in Conservation of Stone Structures in Tanais, Russia

Identification of materials, masonry elements, their shapes, physical and mechanical parameters and type of connection is crucial for the conservation works related to ancient masonry structures. In the case of the archaeological site where the research was carried out (Tanais in Russia), some irregular masonries made of limestone and earth-based mortar were stated. Such type of structures is a common finding during the archaeological excavations in the Black Sea basin carried out by the Division of Fundamental of Building of the Civil Engineering Faculty of the Warsaw University of Technology in cooperation with the Institute of Archaeology of the University of Warsaw and the Antiquity in Southeastern Europe Research Center. The structure of such walls is degraded to a large extent, has low strength, internal cohesion and, as a result—low durability. At the same time, due to their historical importance, proper conservation, as well as the development of the whole methodology for selecting the best composition of earth-based mortar, is of great importance. Presented in the article, research on earth-based mortars were carried out to determine the best way to strengthen them, using cement (creating an earth-based mortar stabilized with cement with the most appropriate recipe) and other substances available in the region where conservation works are carried out not only to improve the durability physical and mechanical parameters but also to achieve the desired esthetic effect in the form of a suitable tone together with the compatibility of repair mortar with the substrate and constitutes the primary stage of creating the whole methodology of selecting a proper composition of earth-based mortar for the conservation of ancient stone structures. In this stage, four criteria were taken into consideration: mechanical (compressive strength test), conservation (compatibility, reversibility, color, texture and surface profile), durability (freeze–thaw test, the appropriate finish of the surface, shrinkage, workability) and technological one (application of materials, technology and techniques available at the conservation area). Applied treatment was evaluated in the next two years of the conservation works. Parameters of repair earth-based mortar stabilized with cement fulfilled all of the above-mentioned requirements.

Ancient masonry structures within an integrated approach: the reinforced corbelled flat roofs of Umm el-Jimal

The historical development of structural engineering design remains a subject separate from other themes in the historical precedents in construction and building materials. Scientists and scholars deal with the engineering performance of historical masonry structures through the traditional ‘geometry’- Galileo’s ‘strength of materials’ theoretical dichotomy. Such approaches emphasize the role of two main aspects in understanding the stability of masonry buildings: form of the structure (arcuated or non-arcuated) and the performance of its building materials in tension and/or in compression. Both theories are questioned because they were not able to comprehensively acknowledge the role of a third important factor- the constructional and reinforcement systems. The study revisits Galileo’s ‘simple beam’ theory and exmines the effect of ‘strength of material’ in relation to the ‘geometrical’ and ‘reinforcement’ criteria. It uses the case of Umm el-Jimal in Jordan because the entire city is built using the sole building material: basalt stone. It explores the different applications of this material in generating reinforced flat structural design through employing diverse corbelling constructional techniques. The study recommends an integrative ‘material-geometry-construction’ approach for masonry structures to ensure a comprehensive understanding of its stability, equilibrium, and safety. It is an approach that could assist structural scholars in their attempts to take precedents as a means to advance contemporary theories in structural engineering.

Earthquake Simulation on Ancient Masonry Buildings

Research on seismic simulations has focused mainly on methodologies specially tailored to civil engineering. However, we have detected a lack in the area of interactive cultural heritage applications, where speed and plausibility are the main requirements to satisfy. We designed a tool that allows setting up and recreating earthquakes in a simple way. We coupled our earthquake simulator with a structural simulator of physics, specifically tailored to masonry buildings, achieving a high degree of accuracy in the simulations. To validate our model, we performed a series of tests over a set of ancient masonry structures such as walls and churches. We show the feasibility of including earthquake simulations and structural vulnerability, a building property that limits the damage of this under seismic movements, into historical studies for helping professionals understand those events of the past where an earthquake took place.

Characterization of ancient building lime mortars of Anhui province, China: A multi‐analytical approach

The characterization of lime mortars has become of primary importance in order to obtain information about the raw ingredients and building technology of ancient masonry structures. Five different samples from Anhui province, China, representing two types of lime mortar‐based materials: joint mortars between the bricks of the city wall and lime mortar sealing a tomb coffin, were collected for analysis. Archaeological information about the samples was reported and studies into the microtextural features and mineralogical compositions of those mortars were performed via a multi‐analytical approach. The joint lime mortars between the bricks of city walls, including Mingzhongdu city wall, Mingzhongdu Xihua gate foundation, Zhengyangguan city wall and She county city wall, were found to be aerial lime mortars. The lime mortar from Nanling Tieguai Song dynasty tomb was analysed and found to be a pozzolanic mortar consisting of lime, clay, sand and cocciopesto‐like materials. The analytical results serve as a critical reference for the maintenance and restoration of ancient city walls in Anhui province, and as a starting point for searching for ancient Chinese pozzolanic mortars and technology for making those mortars.

Mechanical performance of full-scale Pompeii-like masonry panels

Designing suitable structural interventions to preserve ancient masonry structures subjected to seismic activity requires a comprehensive and interdisciplinary knowledge of traditional building techniques. The mechanical properties of materials and the shear behaviour of masonry walls are essential parameters to design suitable interventions for the preservation of ancient assets from the seismic action. However, such information is still lacking for the ancient masonry structures at the archaeological site of Pompeii.This study investigated the shear strength of rubble stone masonry panels. The reproduced full-scale masonry complies with the ancient building technique “opus incertum” identified at the Pompeii site. Three panels were built based on a detailed survey of the ancient masonry structures involved in the 79 AD eruption that first emerged during the new excavation work conducted at Regio V. Original rock units from the ruins of the new excavation area and lime and pozzolana-based mortar produced according to the Vitruvius provisions were used to build the panels. In-situ sonic pulse velocity tests and diagonal compression tests were carried out on the panels in order to identify an appropriate correlation between the results of non-destructive and destructive tests.The realization of the panels is described herein and the results of sonic and diagonal compression tests are presented and discussed.

Effect of eccentricity on retrofitting efficiency of basalt textile reinforced concrete on partially damaged masonry columns

Retrofitting of damaged and/or ancient masonry structures is of significant importance to increase their structural safety. In this study, a retrofitting technique of basalt-textile-reinforced concrete (BTRC) was used to repair partially damaged rectangle masonry columns, and the repairing efficiency was assessed by different parameters. Compression tests with different eccentricities were conducted to explore the mechanical behaviors of initial and BTRC retrofitted masonry columns. The data in terms of crack patterns, load-displacement curves, peak load, ductility and longitudinal strains were analyzed and discussed in depth. Results show that BTRC retrofits can substantially improve the load carrying capacity and ductility of the partially damaged masonry columns under different eccentric loads that display different damage characteristics. The uniaxial constitutive (NTR-PP, NTR-PB and Sargin) models of masonry predict a relatively safe bearing capacity of BTRC-confined columns under eccentric loadings. This BTRC retrofitting technique with the features of cheap, easy-to-construct, long durability and environmental friendliness shows promising potentials in engineering applications. The findings of this study provide an effective way for repairing ancient and/or damaged masonry structures with BTRC.

Seismic Behavior of Brick Masonry Walls Representative of Ancient Chinese Pagoda Walls Subjected to In-plane Cyclic Loading

ABSTRACT Many ancient brick masonry structures were damaged in earthquakes all over the world. Hence, in this study, the seismic behaviors of brick-scaled wall specimens representative of ancient Chinese pagodas were studied subjected to in-plane cyclic loading. Five ½-scale wall specimens with different arched opening sizes were constructed traditionally using aged burnt clay bricks collected from a demolished building and sticky rice mortar. The strength, stiffness, ductility, and energy dissipation capacity of the wall specimens were analyzed. The results showed that the arched opening size and vertical stress had a significant effect on the seismic behaviors of these walls. The damage conditions of the wall specimens at different displacements were also assessed and the assessment results showed that all the wall specimens reached the collapse damage at last.