Ancient Masonry Structures Research Articles

The Important Role of Diagnostics for the Structural Recovery of Historic Buildings

Diagnostic tests represent a fundamental phase of knowledge for historical masonry buildings. The correct design of structural recovery and seismic improvement work must be based on the results of the preliminary tests, for a better knowledge of the vulnerabilities and the mechanical characteristics of ancient masonry structures. The Italian technical codes have given great importance to the level of knowledge reached on the existing buildings, promoting the investment of diagnostics as a fundamental phase of the design work. Two case studies of multidisciplinary diagnostic tests, carried out on monumental buildings, are described for the preliminary evaluation of the quantitative and qualitative characteristics of the masonry structures. In both cases the tests allowed to better understand the vulnerabilities of the masonry section and to design the most appropriate strengthening work. The interpretation of the results coming from tests of different typologies allowed to investigate in depth the hidden peculiarities of the historical masonry structures.

Seismic Behavior of Some Ancient Masonry Structures in Antalya

Seismic Behavior of Some Ancient Masonry Structures in Antalya

Seismic Performance of Ancient Masonry Structures in Korea Rediscovered in 2016 M 5.8 Gyeongju Earthquake

The Gyeongju Historic Areas, which include the millennium-old capital of the Silla Kingdom, are located in the region most frequently affected by seismic events in the Korean peninsula. Despite the numerous earthquakes documented, most of the stone architectural heritage has retained their original forms. This study systematically reviews and categorises studies dealing with the seismic risk assessment of the architectural heritage of the historic areas. It applies research methodologies, such as the evaluation of the engineering characteristics of subsoil in architectural heritage sites, site-specific analysis of the ground motions in response to earthquake scenarios, geographic information system (GIS)-based seismic microzonation according to the geotechnical engineering parameters, reliability assessment of dynamic centrifuge model testing for stone masonry structures and evaluation of seismic behaviour of architectural heritage. The M 5.8 earthquake that hit Gyeongju on September 12, 2016 is analysed from an engineering point of view and the resulting damage to the stone architectural heritage is reported. The study focuses on Cheomseongdae, an astronomical observatory in Gyeongju, whose structural engineering received considerable attention since its seismic resistance was reported after the last earthquake. Dynamic centrifuge model tests applying the Gyeongju Earthquake motions are performed to prove that it is not a coincidence that Cheomseongdae, a masonry structure composed of nearly 400 stone members, survived numerous seismic events for over 1300 years. The structural characteristics of Cheomseongdae, such as the well-compacted filler materials in its lower part, rough inside wall in contrast to the smooth exterior, intersecting stone beams and interlocking headstones are proven to contribute to its overall seismic performance, demonstrating outstanding seismic design technology.

Heterogeneity detection of Portuguese–Brazilian masonries through ultrasonic velocities measurements

In this work, ultrasonic tests were carried out on the external walls of the Nossa Senhora do Rosario dos Pretos Church, an ancient masonry structure from XVIII century, placed at Aracati, Brazil. The main aim of this research is to characterize the ultrasonic velocities of the external walls of the church and identify the heterogeneity of the masonries; to assist furthers maintenance measures, as well to collect quantitative data about the state of conservation of the church. Ultrasonic results are, in general, difficult to analyze, especially due to the variability of the measures way. This way, a methodology to collecting the measures of indirect ultrasonic measurements was developed and it is presented in this paper. This methodology consists in a frame-by-frame comparative analysis of contour maps, obtained from systematic measures of ultrasonic pulse. The method allows the application of indirect ultrasonic measures to characterize clay bricks panels, as well allows the repeatability of further measures in the same points. The results show that ultrasonic tests can be applied for characterize walls homogeneity, offering useful information to control the maintenance or retrofitting measures.

Non-destructive characterization of ancient clay brick walls by indirect ultrasonic measurements

In this work, ultrasonic tests were carried out on the external walls of the Nossa Senhora do Rosário dos Pretos Church, an ancient masonry structure from the 18th century placed at Aracati, Brasil. The main aim of this research was to characterize the ultrasonic velocities of the external walls of the church, in view of further maintenance measures, as well to collect quantitative data on the state of conservation of the church. Fort that purpose, a methodology based on indirect ultrasonic measurements was developed and is presented in this paper. The results show that ultrasonic tests can be applied for characterizing wall homogeneity, offering useful information for control of maintenance or retrofitting measures.

Dynamic response of masonry arch with geometrical irregularities subjected to a pulse-type ground motion

Ancient masonry structures often rely on the masonry arch as a load bearing element. The understanding of its response under seismic actions is a first fundamental step towards the comprehension of the behaviour of more complex structures. It is well known that the stability of masonry arches is primarily related to the geometry. The safety assessment under seismic actions is usually carried out by considering known deterministic geometrical parameters, such as thickness, rise and span, and the voussoirs are assumed with equal dimensions. However, many factors, like defects or irregularities in the shape of the voussoirs and imprecise construction, produce variations of the geometry with respect to the nominal one and, as a consequence, may effect the ability of the arch to resist seismic actions. In this paper, the effect of geometrical irregularities on the dynamic response of circular masonry arches is considered. Irregular geometries are obtained through a random generation of the key geometrical parameters, and the effect of these irregularities is quantified by analysing the dynamic response to ground motion. The masonry arch is modelled as a four-link mechanism, i.e. a system made of three rigid blocks hinged at their ends. The position of the hinges at the instant of activation of the motion is determined through limit analysis. Lagrange’s equations of motion have been written for the generated irregular geometries and solved through numerical integration. The results are summarised by a fragility surface that quantify the extent to which geometrical uncertainties can alter the dynamic response of the masonry arch and increase its seismic vulnerability.

Experimental and numerical assessment of in-plane monotonic response of ancient mortar brick masonry

The structural assessment of extant historical buildings constructed using ancient or traditional masonry is a critical research area for seismic retrofitting. In this study, the in-plane characteristics of the brick masonry of ancient mortars including mud, lime–mud, and lime–sand are investigated experimentally and numerically. For this purpose, several brick masonry prisms are constructed using these mortars. The brick and mortar properties are selected to match those of surviving heritage masonry buildings. Moreover, brick masonry prisms composed of cement and cement–lime (“bastard”) mortars are constructed for comparison. The in-plane responses of these masonry prisms are examined through compression, shear, and tension tests. Failure of brick masonry structure occurs frequently in mortar joints owing to its nonhomogeneous in-plane behavior. The experimental shear and tension responses of masonry joints are used to develop an appropriate contact behavior that can be used for modeling ancient masonry structure in Abaqus FEM software. The experimental tests on masonry prisms are modeled in the software, and the results of the analysis have exhibited reasonable accordance with those of the actual tests.

Preliminary Studies into Methods for Microstructural Improvements of Hydrated Lime Putty

AbstractIn the conservation of ancient masonry structures, due to the scarcity of traditional slaked lime putty, an hydrated lime putty could possibly be used as an alternative binder. The hydrated lime putty can be obtained by soaking the dry hydrated lime powders in water for a certain time. In this article, two approaches to increase the specific surface area of the hydrated lime putty are evaluated. One approach reduces the particle/agglomerate size and the other one mainly aims to promote the formation of Ca(OH)2 hexagonal platelets. Several ways were found to be effective in reducing the particle/agglomerate size, including preselection of high-purity dry hydrated lime with finer particles, by conducation 1-h-long ultrasonication and the addition of 0.5% by weight polycarboxylate-based plasticizer. Meanwhile, a cold-and-hot cycling treatment were found to be effective in promoting the formation of hexagonal platelets of Ca(OH)2. Three cycles, each consisting of 12 h of stirring at room temperature a...

Experimental and numerical analysis of reinforced stone block masonry beams using GFRP reinforcement

This paper deals with an experimental and numerical study of stone block masonry beams externally reinforced using glass fiber-reinforced polymers (GFRP) strips. This study is conducted in order to investigate their flexural behavior. Eight masonry beams with 1.024m span were loaded monotonically up to failure under four-point bending setup. All the tested beams have two courses of stone masonry units. Two unreinforced masonry beams were considered as the reference specimens. The remaining six beams were externally reinforced using hand-made GFRP strips with different layers of chopped glass strand mat (two, three and four layers).In the purpose to replicate ancient stone masonry structures, stone blocks were adopted and lime-based mortar was used to prepare beams. Typical load–displacement curves of the tested beams were compared and discussed.Finite element (FE) modelling analyses, considering the Drucker–Prager criterion, were performed using ABAQUS to predict ultimate loading capacity and the failure mode of the masonry beams. By comparing numerical results with experimental ones, over and above the effectiveness of GFRP strips as external strengthening for stone masonry beams, the proposed finite element model has been validated and can be used for numerical analysis of ancient masonry structures.

Experimental comparison research on the physical–mechanical properties of bonding mortar for repairing seismic damaged ancient masonry pagodas

To conserve the cultural relics of ancient masonry pagodas with suitable materials is very important. In this paper, in order to evaluate the properties of the polymer mortars which have been applied to repair the seismic damaged ancient masonry structure in 2008 Wenchuan earthquake, such as fibre-reinforced mortar, acrylic–emulsion cement mortar, the compressive strength, tensile strength, carbonation and weatherability of the polymer mortar specimens which are simulated, the repair projects were obtained from mechanical tests and freeze-thaw cycling tests. According to the internal microscopic structures from electron microscopy scanning photos, the corresponding porosity of the specimens has been analysed. The reliability of the repair scheme on physical–mechanical properties of the polymer mortars has been appraised and some suggestions have been proposed.

Análisis Límite de estructuras de fábrica como problema de contacto unilateral: un enfoque probabilista

Safety assessment of the historic masonry structures is an open problem. In cases where no slip occurs the application of the standard limit analysis theorems constitutes an excellent tool for its simplicity and robustness. However, if the mechanisms of the onset of collapse involve sliding, it is not guaranteed the existence of a single solution, so it is necessary to look for other ways to treat the uncertainty associated with its multiplicity. We propose a simulation by the Monte Carlo Method for ancient masonry structures modeled as an unilateral contact problem between rigid bodies with friction, as a theoretical basis for further analyses by probabilistic methods computationally less expensive.

Microclimate and Salt Crystallization in the Crypt of Lecce’s Duomo

Ancient masonry structures are often damaged by soluble salt crystallization, which is activated by even small microclimatic variations. Unsuitable environmental conditions can accelerate this process, affecting the type and the quantity of salts and the consequent damage to the masonry. Therefore the importance of monitoring salt diffusion to control salt crystallization and microclimate over time is widely recognized. This study proposes an integrated monitoring methodology to obtain information on the relationship between salt efflorescence and microclimate in the Crypt of the Duomo of Lecce (South Italy). By combining ion chromatography, powder X-ray diffraction analysis, and Raman microscopy with environmental monitoring and deterioration maps, salt components were identified and efflorescence diffusion on masonry was monitored over time. Due to this approach, a possible explanation for the process is finally given.

PERPETUATE guidelines for seismic performance-based assessment of cultural heritage masonry structures

Ancient monumental masonry buildings are complex structures that were not based on an engineered design, underwent many transformations during their life and often present lack of connections among the structural elements. Earthquakes are the main cause of damage for ancient masonry structures and, in order to reduce their vulnerability with compatible and light interventions, it is necessary to have accurate models for the seismic analysis, able to simulate the nonlinear behavior of masonry, and a well defined performance-based assessment procedure, aimed to guarantee the acceptable level of risk for the occupants and for the conservation of the monument itself. The paper outlines the guidelines that were developed within the PERPETUATE European research project. The wide variety of architectural assets is classified and the related proper modeling strategies are identified; moreover, immovable artistic assets are considered in the assessment. A displacement-based approach is adopted, because these structures crack even for low intensity earthquakes and can survive severe ones only if they have a sufficient displacement capacity. Safety and conservation requirements are proposed by considering distinct sets of performance levels, related to use and safety of people, conservation of the building and of the artistic assets that might be present. Some indications on the seismic hazard assessment are provided, considering the distinctive features of some types of ancient structures. Within the fundamental knowledge phase, sensitivity analysis is proposed in order to address and optimize the in-situ investigation and to define proper confidence factors, aimed to consider epistemic and statistical uncertainties. Different modeling approaches and methods of analysis are considered, depending on the characteristics of the structure; both static pushover and incremental dynamic nonlinear analyses are considered. Related verification procedures are defined to evaluate the seismic intensity measure, and the corresponding return period, which is compatible with each performance level that must be fulfilled.

Structural Analysis of Historic Masonry and Technical Guideline Application: The Case of the Insula del Centenario [IX, 8] in Pompeii

In this paper we present the study of an archaeological structure in Pompeii and we detail the difficulties encountered applying the Italian standards and guideline when designing the new roofing structure. Following the latest Italian standards and guidelines, about the assessment and mitigation of seismic risk of cultural heritage, the analysis of the Insula has been carried out. In particular, among all the studied structures, the attention was focused on the covering of the main hall where a prototype of a roofing structure covering a portion of the hall was installed near the remaining ruins of the house. Numerical models have been developed in order to track the effect of these new roofing structures on this ancient masonry structure.

Investigating continual damage of a nineteenth century masonry tunnel

The Shiqiling tunnel, an ancient masonry structure built during 1888–1890, is the first tunnel in Taiwan. Designated as an official monument, the tunnel comprises stone walls and brick or stone vaults. The continual flaking and spalling of bricks in the past two decades prompted thorough tunnel investigations. To avoid any artificial damage, non-destructive technologies are utilised to acquire tunnel data. Visual inspections and mosaicked images reveal prevailing lining anomalies, including spalling, leakage, dislocation and loss of pointing mortar between stones or bricks. Ground-penetrating radar and electrical resistivity imaging suggest that voids exist behind the lining in some areas, and that the water content of rock masses is high. Geodetic survey results show that although continual tunnel deformation produces irregular profiles, an inner boundary exists where masonry blocks crack and fall when surpassing this boundary. Investigation results indicate that the uniaxial compressive failure of bricks and stones accounts for the unusual damage pattern, and the squeezing deformation of the tunnel caused by weathered surrounding rocks is likely to be the cause of the continual spalling phenomena.

Non-Destructive Techniques and Monitoring for the Evolutive Damage Detection of an Ancient Masonry Structure

In the present article non-destructive testing evaluation of the existing damage evolution has been applied to some buildings of the medieval town of Craco (Matera, Italy) and, in particular, to the Normand tower. Actually the little town of Craco is totally abandoned as a consequence of the activation of the landslide motions of its soil depth. Nevertheless, the Normand tower still stands because it is located on a stable and stiffer foundation ground. The tower was built in the XII century. It is 20 m tall and has a symmetric square plan, with dimensions 11 m x 11 m; it was built for defense against enemy attacks. Inside the tower a cistern in reinforced concrete was placed in 1949. It is not connected to the structural walls of the tower; however it represents an obstacle for installing the damage detection equipment and sensors. In this article a preliminary study on the masonry structure of the Normand tower is carried on. A finite element numerical model has been developed and a modal analysis has been performed. The final aim of the research is to find out the evolutionary stage of the cracks and to propose a possible retrofit of the tower.

Experimental Behavior of Natural Fiber-Based Composites Used for Strengthening Masonry Structures

This paper deals with the experimental characterization of the tensile behavior of fiber-based composites and flexural strength of natural fiber-reinforced polymer (NFRP) sheets externally glued on masonry bricks, in terms of load capacity and stress distribution along the bonded length. The bricks adopted for this experimentation are solid clay bricks, typically used in ancient masonry structures. Nonimpregnated and impregnated flax, hemp, jute, and sisal fibers were examined. Two types of matrices have been used, polymer matrices and mortar-based matrices. Composite materials defined as NFRP (Natural Fiber Reinforced Polymer) and NFRG (Natural Fiber Reinforced Grout) were obtained.

Seismic Damage Propagation Prediction in Ancient Masonry Structures: an Application in the Non-Linear Range Via Numerical Models

Preservation of the architectural heritage placed in seismically active regions is a crucial issue. A contribution to dynamic characterization and seismic assessment of medieval masonry structures is provided in a representative single case study, the Archez tower, located in the active seismic area of Malaga, Spain. This study follows a multidisciplinary approach, in order to identify architectural, historical and structural features. The tower exhibits high vulnerability under seismic action, mainly due to its slenderness, low shear strength, low ductility and its possible lack of effective connec- tions among structural elements. To assess its safety, transient and incremental static analyses are performed, aimed at predicting the seismic demand as well as obtaining the expected plastic mechanisms, the distribution of damage and the performance of the building under future earthquakes. A number of three-dimensional linear and non-linear finite element models with different levels of complexity and simplifications are developed, using 3-D solid elements, 3-D beams and macro-elements. All the models assume that the masonry structure is homogeneous, and the material non-linear behaviour -including crushing and cracking- is simulated by means of different constitutive models. Comparison among the different models is discussed, in particular as predicted local and global collapse mechanisms is concerned, to evaluate the suitabil- ity, accuracy and limitations of each analysis.

STABILITY ANALYSES FOR ANCIENT MASONRY STRUCTURES USING DISCONTINUOUS DEFORMATION ANALYSIS AND NUMERICAL MANIFOLD METHOD

In this paper, the stability including stress distribution of two ancient masonry structures, the pyramid of the Pharaoh Khufu, Egypt and the Pont of Gard, were analyzed using discontinuous deformation analysis (DDA) and numerical manifold method (NMM). For the simulation using NMM, the newly developed four-node isoparametric element was used. The stress distributions/concentration were calculated and compared between the two methods. The calculated results show qualitative agreement with observations. DDA and NMM are applicable to simulate the physical phenomena of masonry structures.

Numerical models for the seismic assessment of an old masonry tower

The present paper describes the seismic assessment of the Qutb Minar in Delhi, India. Three models with different levels of complexity and simplification were developed. The use of these models allows one to overcome the complexity of the study of the seismic behavior of ancient masonry structures; by combining the results of the different models it is possible to obtain a better and more comprehensive interpretation of the seismic behavior. The models were used for non-linear static (pushover) and non-linear dynamic analyses. The static and dynamic analyses give different behaviors, indicating that the push-over analysis should be used carefully in the seismic assessment of masonry structures. For the static analysis, the base of the tower is the most vulnerable part; while according to the dynamic analysis, it is the upper part of the tower. This last behavior is according to the historical damage suffered by the tower due to earthquakes. The different behaviors can be explained by the influence of the higher modes of vibration.