Historical Masonry Structures Research Articles

Automatic multi-leaf nonperiodic block-by-block pattern generation and computational analysis of historical masonry structures

In this paper, an automatic block-by-block pattern generator is proposed for multi-leaf nonperiodic masonries. The outcome is then directly employed in block-based computational analysis of full-scale historical masonry structures. Given the 3D volume of the structure (obtainable also from point clouds) and the 3D block definition of a sample, both in terms of voxels, the volume of the structure is automatically filled with blocks by keeping the blocks statistics of the sample, as well as accounting for through-thickness blocks and structural details, such as lintels and edges. A meaningful benchmark is used to assess the efficiency of the filling algorithm, as well as its capability to generate statistically-consistent patterns. The benchmark is then employed in full-scale computational analyses by using an available block-based model. Various multi-leaf patterns are considered and critically compared in structural analysis, highlighting the influence of through-thickness blocks and intralayer mechanical properties on the overall structural response.

Rapid assessment of seismic vulnerability of historic masonry structures through fragility curves approach and national database data

The research focuses on shared built heritage, which forms one of the most vulnerable parts of the building stock in historic centres. To prevent severe damage to this building category and to aid decision-making, the paper presents a rapid seismic vulnerability assessment procedure based on an engineering approach to safety assessment. The construction of fragility curves is developed on a probabilistic framework on the computed set of Safety Factors over a range of considered Peak-Ground-Accelerations. Input data necessary for the computations are extracted from CARTIS database. The methodology is implemented in a spreadsheet combined with a script in Visual Basic for Applications. Two case studies are used to demonstrate the applicability to a single building and at the territorial scale. Results show that the proposed methodology allows for a rapid testing of loss of structural performance given various scenarios, as well as contributing by prioritizing interventions in probabilistic terms.

Fundamental mode shape-based normalization scheme for damage detection of minarets: A non-model-based approach

Historical, cultural, and artistic masonry structures like minarets constructed in regions prone to dynamic effects such as strong winds and earthquakes are vulnerable as a consequence of their slenderness and brittle materials. Structural health monitoring (SHM) has not been employed adequately in the regular control of minarets’ integrity for early warning of disaster. Meanwhile, the protection and preservation of such a cultural inheritance are acute. A non-model-based normalization scheme is proposed to detect damage in minarets based only on the changes in terms of the fundamental mode shape generated by a modest quantity of accelerometers. The backbone idea lies in the similarities in terms of the fundamental mode shape between slender minarets and beam-like structures. Particularly, the modal amplitudes below a specific normalizing node change significantly if damage occurs below this point. Thereby, moving upward the location of this point straightforwardly leads to damage detection of minarets. The proposed technique is implemented on Hacılar mosque’s minaret (24.25 m high) built in 1467 in Bursa city, Türkiye. Reliable damage prediction is attained as long as the modal information is noise-free or reasonable-level noise-polluted.

A Brief Overview on Crack Patterns, Repair and Strengthening of Historical Masonry Structures.

Given that a significant fraction of buildings and architectural heritage in Europe's historical centers are masonry structures, the selection of proper diagnosis, technological surveys, non-destructive testing, and interpretations of crack and decay patterns is paramount for a risk assessment of possible damage. Identifying the possible crack patterns, discontinuities, and associated brittle failure mechanisms within unreinforced masonry under seismic and gravity actions allows for reliable retrofitting interventions. Traditional and modern materials and strengthening techniques create a wide range of compatible, removable, and sustainable conservation strategies. Steel/timber tie-rods are mainly used to support the horizontal thrust of arches, vaults, and roofs and are particularly suitable for better connecting structural elements, e.g., masonry walls and floors. Composite reinforcing systems using carbon, glass fibers, and thin mortar layers can improve tensile resistance, ultimate strength, and displacement capacity to avoid brittle shear failures. This study overviews masonry structural diagnostics and compares traditional and advanced strengthening techniques of masonry walls, arches, vaults, and columns. Several research results in automatic surface crack detection for unreinforced masonry (URM) walls are presented considering crack detection based on machine learning and deep learning algorithms. In addition, the kinematic and static principles of Limit Analysis within the rigid no-tension model framework are presented. The manuscript sets a practical perspective, providing an inclusive list of papers describing the essential latest research in this field; thus, this paper is useful for researchers and practitioners in masonry structures.

Experimental Investigations and Seismic Assessment of a Historical Stone Minaret in Mostar

Minarets, tall structures, connected or not to the mosque attract attention due to their specific architectural features. Vulnerability to seismic damage has been witnessed throughout history on tall and slender structures after earthquake ground motions. In that respect, it is of the utmost importance to investigate the dynamic characteristics and resilience of historical stone minarets. This paper aims to provide the results of an on-site dynamic investigation of a stone minaret in Mostar and deliver its seismic assessment. The minaret is part of the Tabačica mosque built at the turn of the 16th and 17th century in the City of Mostar, Bosnia and Herzegovina. The on-site investigation comprised dynamic identification of the minaret by ambient vibration testing and qualitative estimation of the masonry wall by sonic pulse velocity testing. Besides the modal analysis a time-history analysis was performed by using the Applied Element Method (AEM), considered an appropriate tool for assessing the behavior of historic masonry structures. A good match is found between the first natural frequency obtained by the on-site investigation and the modal analysis which is a solid basis for further seismic assessment of the minaret as a slender tower-like structure. The concentration of stresses is observed at the transition zones.

An integrated approach to the monitoring of rising damp in historic brick masonry

Monitoring rising damp in historic masonry buildings requires an integrated approach, including not only the quantification of moisture in materials over time, but also the investigation of the supply of water from the ground, the evaporative capacity of the surrounding air, and the presence of potentially hygroscopic salts. However, this approach is seldom applied, hence our knowledge of the phenomenon of rising damp in real historic masonry structures is often only partial. In this paper, the proposed approach was applied to the church of Santa Croce in Ravenna, Italy, an outstanding example of masonry building affected by rising damp and related materials’ deterioration. Santa Croce is a Byzantine church surrounded by an archaeological site and the whole area is presently located under the water table level, requiring a continuously operating pumping system to prevent the flooding of the entire zone. The testing and monitoring of moisture and salts in the church’s materials started in September 2020 and is presently running. The data collected so far are presented and discussed in this paper, providing a contribution to a better understanding of this phenomenon. Moreover, during the monitoring period, a pumping system failure caused the flooding of the area in the period August-November 2021, allowing to investigate the impact of this event on the moisture in the materials. The protocol of testing described in this paper may provide a promising and effective method to investigate rising damp and is a starting point in view of its mitigation.

Design of a smart lime mortar with conductive micro and nano fillers for structural health monitoring

Structural health monitoring is an essential tool for assessing the performance of buildings and infrastructure, especially after critical events or the application of structural interventions. When dealing with architectural heritage structures, both structural health monitoring instrumentation and intervention materials need to be as inconspicuous and unintrusive as possible, both in terms of mechanical compatibility and aesthetics. Therefore, the design of smart sensors based on construction materials used in conservation engineering promises to provide an acceptable integrated structural health monitoring and upgrading solution for historic structures. In this paper an experimental investigation of smart intervention materials for historic masonry structures is presented. The materials consisted of natural hydraulic lime mortars modified through the inclusion of electrically conductive micro- and nanofillers: graphite, carbon nanotubes and carbon microfibres. The fillers provide multifunctionality to the matrix material based on an enhancement of its piezoresistive characteristics. Further, they result in an improvement of the mechanical properties of the intervention material without compromising its mechanical and chemical compatibility with the original structure. The resulting materials were evaluated based on mechanical property improvement, piezoresistivity enhancement and ease of production.

Masonry patterns' influence on the damage assessment of URM walls: Current and future trends

While the influence of the component strength on the structural behaviour of Historic Masonry Structures (HMS) is relatively well studied, few studies have investigated masonry textures. Such a research gap is due to the actual difficulty of finding parameters that correlate masonry patterns and structural performances. This paper presents a comprehensive review of the existing geometric measures for irregular masonry patterns, highlighting the gaps and possible future trends. Special attention is paid to the Non-destructive Tests (NDT) for surveying masonry textures and algorithms to generate block-based numerical models artificially. Finally, a numerical investigation underlines how masonry textures generated considering quality indexes present more consistent results.

On the vulnerability features of historical masonry buildings in aggregate

Damage and losses caused by several seismic events revealed the significant seismic risk of existing unreinforced masonry (URM) structures in aggregate, especially when belonging to historical centers of small municipalities. Small historical centers are frequently the consequence of a centuries-long process of building expansion that results in interacting units with varying materials, construction techniques, heights, states of preservation, and, in some cases, spontaneous repairs. All these complicated factors contribute to the fact that seismic assessment of URM buildings in aggregate still constitutes a challenging topic and an open issue both at research level and in engineering practice. Structural irregularities, connection quality among structural parts, diaphragm flexibility, and the lack of aseismic devices are all well-known factors impacting the seismic response of historic masonry structures. Despite that, no univocal answers are available in the literature on the beneficial or detrimental effect for structural units to be in aggregate or not (apart evident cases) neither standardized procedure to quantity such effects as well as the possible interaction between in-plane (IP) damage and local out-of-plane (OOP) mechanisms. After describing the various possible methods for assessing the seismic vulnerability of masonry aggregate, the paper summarizes the key results of an analytical-numerical approach applied to various URM aggregates located in different locations with moderate to high seismic risk. The paper examines the “aggregate-effect” as well as the effects of combining IP and OOP mechanisms on the fragility curves of the case studies. For the first aim, results of structural units analyzed as isolated or inserted in the aggregate are compared by using both nonlinear static analyses (i.e. pushover) and nonlinear dynamic analyses. For the second aim, the findings concern a newly integrated approach for assessing local behaviors and combining them with the global response. In particular, the IP response of URM buildings was simulated through a 3D Equivalent Frame model of the structures, whereas out-of-plane OOP mechanisms were evaluated separately but using floor accelerations derived from post-processing of data from the global 3D model as seismic input, aiming to explicitly consider the filtering effect provided by the non-linear dynamic response of the structure at the different building levels. The outcomes highlight the difficulties of adequately capturing the seismic response of mutually interacting structural units through pushover analyses as well as the impossibility to combine IP and OOP without using sophisticated numerical models.

Finite element model updating of İskenderpaşa mosque and minaret based on experimental measurements

Historical masonry structures have an important place in cultural heritage. Therefore, maintenance of these structures should be made periodically to prevent natural and manmade hazards. The maintenance of these structures is divided into two parts, namely experimental and numerical applications. Experimental, especially non-destructive methods are crucial for increasing the knowledge level of historical structures. Also, experimental tests provide information data that is used in the modal updating process of numerical models. Thus, simulations that are impossible to make experimentally can be easily carried out with updated numerical models. In this paper, a historical masonry mosque called İskenderpaşa and its minaret is investigated by nondestructive experimental tests. Also, finite element models of both structures are created by ANSYS software. To obtain reliable numerical models, finite element model updating processes are made with the aid of experimental data. At the end of the study, the differences between natural frequencies are reduced from 18.6% to 4.9% for the mosque and from 15.2% to 4.8% for the minaret. According to the study, the modulus of elasticity is the most effective update parameter for both structures.

A Methodological Approach to Evaluate Seismic Vulnerability of Masonry Cathedrals

ABSTRACT The seismic analysis of historical and monumental masonry buildings, especially churches and cathedrals, is challenging and expensive. These difficulties are mainly related to complex geometry and the mechanical modelling of historic masonry structures. This paper aims to show the methodological approach to evaluate the seismic vulnerability of Masonry Cathedrals by modelling seismic analysis. The numerical finite element model, modelled with solid elements, was optimised based on identifying the primary dynamic properties performed in ambient and seismic excitations recorded by a continuous dynamic monitoring system in operation since 2015. We carried out linear dynamic analyses for the optimised model of the entire structure. We also carried out non-linear dynamic analyses for the vaults, where damage concentrations were detected after various seismic events. The linear dynamic analysis of the optimised entire structural model aimed to estimate the time histories of acceleration at the connection areas between the vaults to the vertical structures. The numerical analysis results were consistent with the damage maps identified for the actual structure. Furthermore, the numerical model and the analysis procedure showed an excellent ability to reproduce the accurate structural response.

Factors Affecting the Seismic Analysis of Historical Masonry Structures: Case of a Single-Nave Church Damaged during the 2009 L’Aquila Earthquake

The post-earthquake seismic assessment of buildings is usually performed through numerical methods. Geometrical simplifications of the structure are often introduced. Moreover, the seismic input is evaluated following the indications of reference standards, although overestimated forces may be obtained compared with those that actually occurred. In this paper, through the case study of a single-nave church, the significant influence of the geometric modeling of the roof on the structural response and the importance of the correct definition of the seismic input in post-earthquake analyses are shown, even in the case of very simple structural organisms. A preliminary limit analysis and nonlinear static analyses, after the definition of new response spectra based on a subset of the recorded ground accelerations, have been performed. The decisive role played by the correct geometric modeling and the proposed response spectra in the simulation of the overall response and damage status is shown. Finally, the importance of the method in the design of retrofitting works is highlighted through the basic example of the numerical response of the structure reinforced with CFRP composite.

Influence of soil–structure interaction on seismic demands of historic masonry structure of Kashan Grand Bazaar

Heritage structures are an important part of the history of each community as well as an economic resource. This study aims to investigate the earthquake damage and failure mechanism of a historic Bazaar located in Kashan (center of Iran), which dates back to the eighteenth century. Numerical models were built by a macro method, considering two cases of fixed support and soil–structure interaction (SSI). To assess the structural behavior, modal, nonlinear static, and dynamic time history analyses were performed using a three dimensional finite element method. The results of SSI analysis show an intense weakness of the structure against the required demand based on the design spectrum. Also, foundation flexibility has a great impact on the vibration characteristics, displacement demand, and damage distribution. By comparing the results of time history analysis to the pushover procedure, a lower shear value and higher displacement are obtained. Furthermore, the damage process is as dome collapse alongside short arch, consequently long arch collapse followed by pier wall overturning.

Influence of the method of numerical modelling of the connections of the roof truss and vaults with the walls of historic masonry structures on local stress distribution

Influence of the method of numerical modelling of the connections of the roof truss and vaults with the walls of historic masonry structures on local stress distribution

Dynamic monitoring of a tunnel-like masonry structure using wireless sensor networks

The application of wireless sensor network technology for long-term monitoring of a historic tunnel-like masonry structure in Italy is described. The monitoring was performed within the activity of a research project aimed at providing a general framework to check the structural health of heritage structures and detect, in real time, any potential damage that may compromise their safety. The selected case study (a tunnel-like masonry structure) represented a challenging experiment, both in terms of the type of structure itself and the technical solution employed for installing the monitoring system. After a brief description of the installed monitoring system and the design of the sensor layout, the lessons learned after 1 year of monitoring are summarised.

Effect of SSI and Fixed-base Concept on the Dynamic Responses of Masonry Bridge Structures, Dalal Bridge as a Case Study

Historical masonry structures are very important as they carry cultural heritage, so it is important to protect these structures from natural disasters such as earthquakes and transferred to the next generations. It is known that masonry structures are weak against earthquakes, therefore, a suitable analysis method for assessment and retrofitting purposes is a must. Generally, the fixed-base concept is used for analysis and design purposes, however, in reality, the structures are not fixed-base but they are resting on soils. The aim of this study is to make a comparison study between dynamic responses of fixed-base and soil-structure interaction (SSI) models for bridge masonry structures, the historical Dalal bridge was selected as the case study. First, the bridge was modeled as a fixed base model, and then three different soil profiles (hard, medium and soft soils) were added to the underneath of the structure. The numerical models were analyzed under Elcentro earthquake record. Results indicating a good agreement between the fixed base and the case of hard soil base. However, considerable differences were observed for medium and soft soil profiles.

Investigation of Drift-based Damage Limit States for Historical Masonry Structures

ABSTRACT Drift-based performance assessment has been a practical tool among the research and engineering community. However, several studies showed that there are several critical issues such as seismic damage definitions and their quantifications related to the displacement-based approach when it is applied not only to modern masonry structures but also to historical ones. The main reason is due to (i) failure mode dependency, (ii) geometry, loading and boundary conditions, (iii) inadequate prediction of the failure modes based on in-plane capacity formulations given in the codes. The present article discusses the reliability of drift limit values proposed by different codes and guidelines by comparing drift values derived in two datasets of masonry piers through considering an application to a real case study. It is observed that performance-based assessment is mainly based on the failure mode of the masonry structure, while the Guideline for Earthquake Risk Management of Historical Structures in Turkey, which is widely used in practice, proposes drift limits that are independent of the masonry behavior. Without consideration of the behavior mode can lead to incorrect assumptions and hence unconservative performance assessment outcomes for the architectural heritage.

Experimental out-of-plane damage limits of historical stone masonry walls

In stone masonry buildings, failure under strong ground motions usually occurs in the form of out-of-plane overturning of the walls before reaching their in-plane strength, as the walls have long unsupported spans perpendicular to their plane and the lack of slabs ensuring a diaphragm effect. Post-earthquake damage observations reveal this specific weakness of the historic masonry walls. Experimental determination of the out-of-plane damage limits of these walls, emerges as a need for use, especially during numerical evaluations. This article presents the results of static and dynamic testing of double- and three-leaf large-scale U-shaped masonry wall specimens. For this purpose, nondestructive material characterization was conducted on a reference historical masonry structure. Large-scale wall specimens were designed considering these findings and material tests performed on mortar samples. Quasi-static cyclic tests and ambient vibration tests for both initial and damaged conditions were performed on these specimens to capture the damage evolution and the corresponding drift limits. Damage limits are suggested to be used in performance-based evaluations of other territorial structures.

Influence of Freeze/Thaw and Alkaline Environment on the Mechanical Properties of a C-FRCM System Bonded on Masonry Substrate

The Fabric Reinforced Cementitious Matrix (FRCM) system in the last two decades was used to strengthen and rehabilitate historical masonry structures as an alternative of the well-known Fiber-Reinforced Polymer (FRP) system. The FRCM systems consist of different types of fiber in form of fabric mesh immersed in a cementitious/hydraulic or lime matrix; they present better compatibility with the substrate and less limitations in heritage applications. However, the durability and the interaction FRCM-substrate under the artificial aging mechanism in aggressive environment is not well known. The paper reports and discuss the first results of an experimental program planned to investigate the durability of some FRCM systems. The effects of the freeze/thaw and alkaline environment on both the mechanical properties of the FRCM coupons and the bond FRCM-to-masonry substrate were analyzed by the results of direct tensile and single-lap shear tests.

In-plane retrofitting of masonry structures by using GFRP strips in the bedjoints

Many unreinforced masonry structures were vulnerable in the past earthquakes and required retrofitting. The vulnerability of masonry structures could solve by providing numerous retrofitting approaches. However, the lack of appropriate methods, which could provide a solution for historical masonry structures with lesser effects on their façade, is demanding. In this study, two one-third scale masonry wall specimens made by clay bricks were tested under constant vertical and cyclic lateral loading. The specimens consist of an unreinforced wall and a wall retrofitted by GFRP strips. This study investigates the seismic behavior of unreinforced masonry walls before and after using GFRP strips on their bedjoints. To this purpose, various patterns of using GFRP strips have been studied by simplified micro-modeling. The results indicate that the proposed retrofitting technique could improve the lateral strength and stiffness of the unreinforced masonry wall with a considerable increase in the absorbed and dissipated energy and ductility content that changes the wall’s brittle failure to the ductile one. The proposed method could apply to the modern historical structures in which cement mortar has been used as an adhesive between the masonry layers.