Historical Masonry Research Articles

Estimation of Mechanical Properties and Mass Density of Al-Malwiya Masonry

Abstract This paper presents the first estimation for the mechanical properties and the mass density of the masonry of Al-Malwiya heritage minaret. Many approaches are investigated in order to estimate the modulus of elasticity, shear modulus, Poisson’s ratio, and the mass density for this historic masonry. The mechanical properties are estimated by using empirical formulas and analytical equations, while the mass density is estimated after carrying out experimental tests for the extracted samples of the historic mortar. The estimated properties showed relatively low values compared with the newly constructed masonries, but they were interpreted as reasonable for such a historic construction.

Influence of time intervals of microwave drying of masonry on the final result of drying

In the area of drying damp masonry, we already know the discussed method of microwave drying. This method is indestructive, which is why it is considered to be used for listed heritage buildings. Even though there was much research done already on this topic, we are still missing answers for some questions regarding particular methodological procedures. This contribution is focused on the impact of time intervals of microwave drying on the final result of masonry drying. The experiment was done on historical masonry of CPP and on ceramic masonry. Two laboratory samples were made out of each type of masonry, to which we applied microwave drying in different time intervals. Difference was in both time of drying and time of pauses between them. The aim was to set an ideal interval of drying.

Construction types and typologies of existing masonry arch bridges in Croatia

Historical masonry arch bridges still form an important part of Croatian transportation network. There are approximately 680 masonry arch bridges and culverts currently being used for railways and roadways. Many of these bridges are relatively old (more than hundred years in most cases) but still in usage. Increasing vehicle load and speeds as well as deterioration due to anthropogenic and environmental influence have highlighted the need for reliable assessment of their service condition and regular maintenance. The aim of this study is to provide a review of existing masonry arch bridges in Croatia. Firstly, a historical review of bridges is given showing the time period in which they were built, indicating the materials and design principles used for their construction. Next, bridge typologies are presented as well as their detailed analysis of geometric characteristics for brickwork bridges. Finally, a short review of damages and their impact on serviceability of bridges is given. This review presents masonry arch bridges in Croatia and the need for reliable method of assessing their service condition in order to provide proper maintenance, repairing and retrofitting.

Analysis of Tram Traffic-Induced Vibration Influence on Earthquake Damaged Buildings

The Zagreb 2020 earthquake severely damaged the historic centre of the city. Most of the damage occurred on historic masonry residential buildings, many of which are situated very close to the tram track. Although traffic-induced vibrations generally do not affect surrounding buildings, they can be harmful to buildings damaged by a previous earthquake. Vibrations could contribute to the further propagation of existing cracks. The effect of vibrations depends on many factors, one of the most important being the distance between the track and the building. The vibrations are highest at the source, and the energy loss occurs due to transfer through the soil to the recipients. The impact of tram-induced vibrations on earthquake-damaged buildings in the city of Zagreb is investigated in this paper. The analysis is conducted on a tramway network scale to identify critical locations by performing continuous monitoring on the tramway network and risk analysis based on the distance of buildings from the track, vibration amplitude at source, and building damage. Further investigation is based on the level of buildings to evaluate the influence of vibrations on actual buildings damaged in the Zagreb earthquake. Based on detailed signal analysis, the vibration characterization is performed, and the influence on damaged masonry buildings is evaluated.

Experimental setup and numerical evaluation of the compression test on thin tiles for masonry timbrel vaults

Compressive tests on clay tiles used in historical masonry timbrel vaults are hindered by the relatively small thickness of the specimens, resulting in buckling or confinement problems depending on the loading direction. This paper presents an experimental campaign and a numerical validation of a novel testing setup for estimating the compressive strength of thin clay tiles used in timbrel vaults. The experimental campaign focuses on two different types corresponding to historical and modern handmade tiles. Experimental and numerical results show that the proposed test setup can be used for the estimation of the compressive strength of thin clay tiles.

Comparation of Two Different Methods for Fighting Moisture in Historic Masonry

Nearby all historic building built in Central Europe before the half of the 20th century have to face problems with unwanted moistening of their constructions. A significant part of them stands under legal protection as architectural monuments. There are several technologies which can be used to deal with this problem. Some of them are more invasive into historical masonry, some of them are less invasive. Some of them are much more effective in insulating effort, some of them are less. According to the Venice charter from 1964 methods which are less invasive should be preferred. Some of them are the ventilation methods. But are they really effective? On the other side of the spectrum are undercutting methods, which are drastically invasive. So, they are standing in a clear opposition the recommendations of the Venice charter. Why should they be used? Are they really so effective? And what should be done with their conflict with the Venice charter? The article tries to find answers on these questions on a base of introduced anti-moistening technologies from both sides of the mentioned spectrum. From a couple of renovation interventions undertaken in Slovakia, in the climate of Central Europe, two typical examples were taken out to support a – hopefully – right result. We used natural ventilation in a church in Western Slovakia and we achieved a success. Then we used the undercutting technology in some other church - again in Western Slovakia. We were also successful. So what is the matter? The matter is that one of this method was not successful in an adequate extend. The other one was.

Hygrothermal assessment of internally insulated historic solid masonry walls with focus on the thermal bridge due to internal partition walls

This study investigated the hygrothermal performance of five insulation systems for internal retrofitting purposes. Focus was on the hygrothermal performance near partition brick walls compared to the middle of the wall. The setup comprised two insulated reefer containers with controlled indoor climate, reconfigured with several holes containing solid masonry walls with interior embedded wooden elements, an internal brick partition wall and different internal insulation systems, with and without exterior hydrophobisation. Relative humidity and temperature were measured over five years in the masonry/insulation interface and near the interior surface, in the centre of the test field and near the partition wall. In addition, calibrated numerical simulations were performed for further investigation of the thermal bridge effect. Findings for the masonry/insulation interface showed higher temperatures and lower relative humidity near the partition wall in comparison with the central part of the wall. Near the interior surface, measurements showed only minor differences between the two locations. The relative effect of the thermal bridge was smaller in the case of a high driving rain load on the exterior surfaces. The numerical simulations showed that the hygrothermal conditions were affected further away from the partition wall than what could be measured in the experimental setup.

Seismic risk assessment and intervention prioritization for Italian medieval churches

Rapid seismic risk assessments are critical to help practitioners, facility stakeholders, architectural heritage superintendence, and insurance companies in their asset management decision-making processes. In particular, the integrity of the Italian church portfolio has often been threatened by earthquakes. The Italian church portfolio includes thousands of religious buildings, representing pivotal facilities for the religious community, thus requiring an assessment methodology which accounts for the structural, architectural, cultural, and functional facets of churches. The methodology proposed herein combined both widely applied assessment techniques regarding structural vulnerability (e.g., “macro-blocks”) with a newly developed framework accounting for other important variables (e.g., the heritage significance of a church) to produce a rapid, quantifiable, and holistic approach to determine the relative seismic risk assessment of historic masonry churches. On-site surveys of 72 unreinforced masonry medieval churches across Italy were conducted. Following a hierarchical approach for the surveys, each risk component – hazard, vulnerability, exposure, and consequence – was defined throughout by the development of 13 different indices. Using the fuzzy set theory, the indices were aggregated into a final risk rating framework useful to provide stakeholders with a scientific-based prioritization list for the maintenance and strengthening intervention of their church portfolios.

Spectral analysis of surface waves for non-destructive evaluation of historic masonry buildings

Spectral Analysis of Surface Waves (SASW) is an in-situ non-destructive testing technique which allows to evaluate historic masonry buildings by characterising the mechanical properties of the materials without damaging the structure. This paper presents the theoretical bases of this technique and describes its application on an existing masonry structure, the church of San Justo y Pastor in Granada (Spain). The elastic modulus, shear modulus and Poisson’s ratio of the two carbonate rocks composing the building were calculated, obtaining results that are in agreement with previous studies using different testing techniques. The results of the study indicate the usefulness of SASW method to evaluate heritage buildings, taking into account the existing variability of the mechanical properties throughout the structure.

Role of model identification and analysis method in the seismic assessment of historical masonry towers

The seismic assessment of historical monuments typically involves many issues, the most crucial of which are: retrieving geometrical and mechanical data; implementing a suitable numerical model; choosing the more appropriate type of analysis and properly interpreting the results. The more well-managed these issues are the better the reliability of the seismic assessment. The Civic Tower of L'Aquila (Italy) is considered in this paper as a typical case in which lack of data and discrepancy of sources make the seismic assessment hard to be suitably performed. The key role of the identification of the numerical model was firstly evidenced. Different numerical models were implemented to identify the best-fitting geometrical and mechanical properties of the structure. The considered case-study also led to the discussion of some issues concerning the identification of the numerical model of historical towers. Code-compliant linear and non-linear dynamic analyses were then carried out to compare the seismic performance of the tower assessed through the different methods based on regulations. A concrete damage plasticity model for masonry and a set of spectrum-consistent earthquakes were adopted. The stress maps, the horizontal displacement peaks (useful to avoid the pounding phenomenon with the adjacent Margherita palace), and the evolution of damage were investigated. The study highlighted that the widely adopted response-spectrum modal analysis (RSMA) may underestimate -even remarkably-the displacement demand compared to the more rigorous time-history linear analysis (THLA), this being an inconsistency of the code-compliant linear analyses. On the other hand, the results of the non-linear time-history analysis (NLTHA) confirmed the displacement demand predicted by the THLA, while the damage evolution under tensile stress was found in agreement with the crack pattern detected on the structure. The influence of the vertical component of the earthquake was also investigated, founding that the vertical component of the ground motion does not significantly affect the results.

Advanced Modeling of a Historical Masonry Umbrella Vault: Settlement Analysis and Crack Tracking via Adaptive NURBS Kinematic Analysis

AbstractIn this work, the study of a complex masonry umbrella vault located within Masegra Castle (Museum of Sondrio territory, Northern Italy) is presented. Built during the renewal of the castle ...

Temporary Shoring System on Masonry Buildings After an Earthquake

Historical masonry structures that make up the cultural assets of a country constitute the identity of the society to which it belongs. For this reason, it should be protected and should be transferred from generation to generation. Earthquakes are threatening action to masonry structures. The force generated by the ground movement may cause shear cracks in masonry structures that may lead to fragmentation and even collapse of the structure. It is necessary to know the earthquake behaviour of masonry structures to be able to apply appropriate temporary shoring system after a damage caused by earthquake in order to prevent the future damages during aftershocks. Thus, the progress of the damages in the building is prevented and it is ensured to survive until detailed investigation or restoration. However, when the applied temporary shoring system designs were examined, the environmental conditions of the building were not taken into account in any guideline on immediate shoring. In this paper, temporary shoring system for 3 traditional houses of Bey District is designed for possible earthquake damages. This district has many registered civil architectures lined side by side along very narrow streets. Some masonry buildings were changed to reinforced concrete with multiple floors. This study includes the registration status of the buildings, their location, the number of floors to be supported, the heights between floors, the height of the forces that can be brought by the adjacent building elements, the width of the street where the facade to be supported, whether there is a window or door opening in the facade to be supported etc. If there are window or door openings, the distances of the opening to the corner points of the building and the distances between the two openings has to be recorded. According to these determinations, possible damages that may occur in the buildings are defined and a temporary shoring system is designed in accordance with the buildings and the surrounding conditions.

Recent progress of SPIDER: Aspects of subtractive approaches to existing building’s performance improvement

This contribution reports about methodology, progress and preliminary findings of a recent exploratory Research and Development project, pertaining to the (semi-)automated thermal retrofit of existing building’s envelopes. Thereby, the potential of robots, which autonomously identify areas of facades that can be used for inserting openings into the existing wall material, is examined. The idea is based on the fact that masonry walls of historic masonry walls (especially of Gründerzeit buildings built between 1850 and 1918) often have been structurally over-dimensioned. As such, the spare thickness of the walls could be used for thermal insulation purposes. The initial idea to implement air cavities for insulation purposes is in correspondence with the predominant functional principle of most insulation materials.

Dynamic Identification Tests of 20th Century Historic Masonry Buildings in Japan

This paper discussed the application of health monitoring systems to 20th-century historic buildings. Natural disasters are major threats to monuments. They are often seismically vulnerable and require interventions. However, taking into account their historic and cultural values, it is appropriate to observe long-term behaviour before making a decision on intervention schemes. To this aim, health monitoring is considered an effective approach. In recent years, MEMS (micro-electromechanical systems) accelerometers have been attracting attention for their convenience and efficacy. Nonetheless, the reliability of MEMS accelerometers still needs to be examined for the monitoring of monuments as sufficient research contributions have not been made. This paper presented two case studies that were monitored by means of MEMS accelerometers. They were masonry structures positioned in seismic-prone regions in Japan. A number of earthquakes were detected by the accelerometers during one year of monitoring. To examine the accuracy of the adopted MEMS accelerometers, dynamic identification tests were conducted using high-sensitivity strain-gauge accelerometers and servo velocity meters. Based on responses obtained from the tests, numerical simulation was performed. Nonlinear static analysis was performed. The numerical simulation permitted the comparison of reliability among sensors and test types. This paper provided suggestions for the dynamic identification tests of heritage structures.

Compression and In-plane Seismic Behaviour of Ashlar Three-leaf Stone Masonry Walls

ABSTRACT There is a lack of knowledge regarding the parameters needed for the effective seismic performance assessment of historical stone masonry buildings. The paper presents the results of an extensive experimental campaign consisting of four compression and fifteen in-plane cyclic shear tests on three-leaf ashlar stone masonry walls and its constituents. The morphology, level of vertical load, and testing boundary conditions were systematically varied, and their influence on the load-bearing and deformation capacities, stiffness, ductility and energy dissipation was analysed. Good consolidation of the inner core enables in-plane failure mechanism of the walls to occur without decisive out-of-plane damage. The boundary conditions applied significantly influence the failure modes and large deformation capacities obtained, whereas transverse connections in the case of a shear failure mechanism do not significantly influence the overall lateral in-plane response of walls.

Natural-Fibrous Lime-Based Mortar for the Rapid Retrofitting of Heritage Masonry Buildings

The present work aims to define the mechanical behavior of a new composite material for the preservation and enhancement of the vast historical and architectural heritage particularly vulnerable to environmental and seismic actions. The new composite represents a novelty in the landscape of the fibrous mortars and consists of natural hydraulic lime (NHL)-based mortar, strengthened by Sisal short fibers randomly oriented in the mortar matrix. The developed mortar ensures the chemical-physical compatibility with the original features of the historical masonry structures (especially in stone and clay) aiming to pursue the effectiveness and durability of the intervention. The use of vegetal fibers (i.e., the Sisal one) is an exciting challenge for the construction industry considering that they require a lower level of industrialization for their processing, and therefore, their costs are considerably lower, as compared to the most common synthetic/metal fibers. Samples of Sisal-composite are tested in three-point bending, aiming to estimate both their bending stress and fracture energy. Tensile and compressive tests were also performed on the composite samples, while water retention and slump test were performed on the fresh mix. At last, the tensile tests on the Sisal strand were performed to evaluate the tensile stress of both strand and wire. An original mechanical interpretation is proposed to explain two interesting phenomena that arose from the analysis of experimental data. The comparison among the performances of unreinforced and reinforced mortar suggests that the use of short fibers is recommendable as coating in the retrofitting interventions alternatively to the long uni or bi-directional fiber strands adopted in the classic fibrous reinforcement (i.e., FRCM). The proposed composite also ensures mix-independent great workability, excellent ductility, and strength, and it can be considered a promising alternative to the classic fiber-reinforcing systems. As final remarks, the use of fiber F1 (length of 24 mm) with respect to fiber F2 (length of 13 mm) is more recommendable in the retrofitting interventions of historical buildings, ensuring higher strength and/or ductility for the composite.

Real-time Structural Stability of Domes through Limit Analysis: Application to St. Peter’s Dome

ABSTRACT A digital tool is presented and made available for the rapid structural assessment of historic masonry domes. It is especially suited for masonry domes that present long meridian cracks; ergo partitioned slices governed by a pushing failure mode. The proposed procedure considers a Heyman’s no-tension mechanical model that has been implemented within a user-friendly visual programming environment. The numerical approach includes parametric modelling of the failure mechanism that allows exploring the domain of solutions using the kinematic theorem of limit analysis. A heuristic search method is subsequently adopted to refine the geometry of the collapse mechanism and to compute the value of the horizontal trust. Validation of the results has been achieved considering St. Peter’s dome. As reported in the literature, the behaviour of this dome shifted from a rigid shell-type — stiffened by hoop stresses — towards a pushing type of dome partitioned by long meridian cracks. Unlike time-consuming and advanced methods of analysis, the present procedure allows the users to perform a structural assessment of a historic masonry dome in a few seconds and offers the possibility of including: (i) the dome’s drum in the analysis, if applicable; and (ii) rings as strengthening measure, whose number, position (dome or drum) and material (capacity) are user-defined. The goal is to make the tool easily and freely available at the disposal of students, researchers, and structural engineers.

The effect of ground motion vertical component on the seismic response of historical masonry buildings: The case study of the Banloc Castle in Romania

The current paper aims at analysing the effect of ground motion vertical component in the case of near-field excitations on the structural response of historical masonry buildings. In this perspective, the Banloc Castle in Romania has been considered as a reference case study. This historical masonry structure was damaged by the Banat-Voiteg earthquake that occurred in December 1991 in the homonymous city. To this purpose, a FEM model of the building, set up using the DIANA FEA analysis software, has been studied in the non-linear dynamic field considering a real ground motion record based on specific source-to-site distance, moment magnitude and focal depth. The effects of the impulsive earthquake have been evaluated considering the main engineering demand parameters, such as displacements and forces, focusing on two different scenarios, namely horizontal and horizontal + vertical ground motions. The obtained results have shown that the vertical ground motion sensibly modifies the structural capacity of the building since it produces a relevant modification of the in-plane walls behaviour and the stress conditions. Important considerations about the behaviour (or seismic response modification) factor, ductility and stress in terms of axial and shear forces have been provided. Moreover, numerical damage patterns have been compared to the real cracks detected. Finally, a set of fragility curves has been derived taking into consideration the near-field effects.

Performance of a Salt-Accumulating Substitution Lime Render for Salt Laden Historic Masonry Walls

Salt crystallization is one of the main decay processes in historic masonry mortars, and climate change can worsen the salt weathering effects on those materials as result of, e.g., more often rain falls, more intense solar radiation and sea level rise. In this paper, the effectiveness and durability of a substitution “ventilated render” system (a two-layer render, with base and outer layer and “vertical grooves” in the base layer) on a full-scale salt laden masonry wall to reproduce conditions that may be found in real cases was investigated. The crystallization at the interface between render layers and in vertical grooves and the effect of the porous structure on salt crystallization were thoroughly investigated. It was highlighted the reliability of the results of the salt crystallization testing procedure on a full-scale masonry wall to attest the efficiency and durability of the render system. Finally, it was proven that the ventilated render system with water repellent in the outer layer is durable and efficient enough to be used as a substitution render on salt laden historical masonries, acting as a salt accumulation render where salts preferably crystallize in, delaying the damage on the outer surface without introducing harmful effects in the masonry.

A Parametric Scan-to-FEM Framework for the Digital Twin Generation of Historic Masonry Structures

Historic masonry buildings are characterised by uniqueness, which is intrinsically present in their building techniques, morphological features, architectural decorations, artworks, etc. From the modelling point of view, the degree of detail reached on transforming discrete digital representations of historic buildings, e.g., point clouds, into 3D objects and elements strongly depends on the final purpose of the project. For instance, structural engineers involved in the conservation process of built heritage aim to represent the structural system rigorously, neglecting architectural decorations and other details. Following this principle, the software industry is focusing on the definition of a parametric modelling approach, which allows performing the transition from half-raw survey data (point clouds) to geometrical entities in nearly no time. In this paper, a novel parametric Scan-to-FEM approach suitable for architectural heritage is presented. The proposed strategy uses the Generative Programming paradigm implementing a modelling framework into a visual programming environment. Such an approach starts from the 3D survey of the case-study structure and culminates with the definition of a detailed finite element model that can be exploited to predict future scenarios. This approach is appropriate for architectural heritage characterised by symmetries, repetition of modules and architectural orders, making the Scan-to-FEM transition fast and efficient. A Portuguese monument is adopted as a pilot case to validate the proposed procedure. In order to obtain a proper digital twin of this structure, the generated parametric model is imported into an FE environment and then calibrated via an inverse dynamic problem, using as reference metrics the modal properties identified from field acceleration data recorded before and after a retrofitting intervention. After assessing the effectiveness of the strengthening measures, the digital twin ability of reproducing past and future damage scenarios of the church is validated through nonlinear static analyses.