Typical Masonry Research Articles

Seismic vulnerability assessment and strengthening of an existing typical Indian unreinforced masonry building in a high-risk seismic zone-a comprehensive application

Seismic vulnerability assessment and strengthening of an existing typical Indian unreinforced masonry building in a high-risk seismic zone-a comprehensive application

Experimentally‐based in‐plane drift limits for the upper threshold of masonry light damage

AbstractDrift limits are useful thresholds; during design or retrofitting analyses, engineers can compare the expected behaviour of a structure to drift limits that predict when the structure will reach a certain condition. This helps ensure that structures satisfy specified performance goals when exposed to certain hazards. Masonry walls are susceptible to damage from lateral in‐plane actions such as wind or earthquake loading; ensuring that in‐plane drift remains sufficiently small will help limit this damage. Drift limits based on crack‐based damage are scarce, however, with DS1 limits being extrapolated from higher damage grades based on structural strength capacity or ductility. In this work, crack‐based damage is evaluated on a multitude of full‐scale experimental walls surveyed with digital image correlation. This method observes the initiation and propagation of cracking. Cyclically incremental in‐plane tests provide a range of drift‐damage relationships. These are explored with machine learning to determine influential predictors and ultimately establish drift limits for light damage. Two types of brick masonry are explored: fired‐clay and calcium‐silicate. For the latter, light damage begins at an in‐plane drift of 0.5 mm/m and can extend to 4.8 mm/m (or 0.48%) for the former before the masonry surpasses light damage and reaches structural damage grades. In comparison to drift limits set by other authors and (international) guidelines to characterise light damage, significant damage, or the ultimate capacity of masonry walls, the resulting drift limits for light damage from this work are set directly on the basis of experiments and are in good agreement with other authors. Most importantly, all the consulted values for ultimate capacity are much larger than the upper threshold for light damage determined herein, with limits for significant damage in the same order of magnitude. This result verifies the accuracy of the experimental crack‐based characterisation used to establish the drift thresholds.

Experimental analysis of the bond-slip characteristics between CFRP and natural stone masonry units

Purpose Although the reinforcement of concrete and brick masonry with fiber-reinforced polymer (FRP) has been extensively researched, its application and impact on natural stone, especially in historic preservation, have received less attention. This study aims to examine the bond-slip characteristics of carbon fiber-reinforced polymer (CFRP) with two types of natural stone masonry, aiming to enhance their effectiveness in reinforcing historic structures. The stones studied include one from the Chouf-Lekdad region (A) and another from a historic structure in Sétif City (B). Both stones were strengthened using CFRP and carbon fiber fabric (CFF) through near-surface mount (NSM) and external bonding (EBR) techniques. Design/methodology/approach The interaction was assessed during the pull-out test by analyzing the stress transfer mechanisms, adhesion and deformation. This study also examines the effects of the following parameters on the bond between CFRP and stone: type of stone (A and B), type of reinforcement (plat CFRP and CFF), various notch shapes and sizes (bp, tp and Lb), and reinforcement techniques (NSM and EBR). Findings This study demonstrated the practicality and effectiveness of enhancing natural stone masonry of old buildings by integrating NSM and EBR techniques with CFRP. With a bond length of 30 mm, the pull-out force correlates with the strength of the stone. This indicates the importance of stone strength in obtaining better adhesion. The CFF–resin interface is more cohesive than the CFRP plate–resin interface because the resin penetrates the flexible CFF strip, ensuring better adhesion. In contrast, the CFRP plate interface is rigid and smooth. The results suggest that natural stone–CFRP adhesion is more effective than CFRP bonded to concrete and brick masonry due to the stone's strong resistance. Originality/value This experimental investigation provides new study into the bond-slip behavior of CFRP-reinforced natural stone masonry, filling the gap in existing research. The findings offer useful direction for creating FRP strengthening solutions that are specifically adapted to the properties of natural stone used in historic constructions. This study helps to improve preservation procedures by guiding the selection of reinforcing techniques, such as NSM versus EBR, and finding ideal bond lengths. This work's novelty stems from its ability to improve the structural integrity of culturally significant buildings while preserving their historical authenticity.

A unified theory for predicting the compressive stress–strain curve of concrete block masonry

I-type internal structures are commonly present in concrete hollow block masonry. A unified theory based on I-type internal structures is proposed to analyze types of masonry systematically. In this unified theory, the I-type element represents the I-type internal structure; the equivalent frame is introduced to analyze the interaction between the block and grout; and the characteristic strength of mortar is employed to measure the performance of mortar in masonry. Each subtheory of the unified theory is independent, and the application scope of this theory can be expanded by adjusting the subtheories. The predictions of the unified theory for the compressive behaviors of fully grouted, partially grouted, and ungrouted masonry are well matched with the measured data. Through targeted adjustments, the prediction of this theory for special cases is also accurate. The calculation results suggest that the unified theory can effectively analyze different types of masonry with an I-type internal structure.

Out-of-plane behavior of unreinforced masonry walls with horizontal slip layers in RC frames

In some cases, the infilled walls may be subjected to in-plane（IP） earthquake and out-of-plane(OOP) earthquake action due to the uncertainty of earthquake action and infills’ position. As a new type of unreinforced masonry(URM) walls with horizontal slip layers, it can effectively reduce the in-plane damage of infilled walls of reinforced concrete frames under an earthquake. However，the infill wall out-of-plane damage has a greater security threat than in-plane damage. In this study, a numerical study about the difference of OOP behavior of URM walls with/without horizontal sliding layers are analyzed, mainly including failure mode, bearing capacity, displacement capacity and stiffness. The spacing of horizontal slip layers, length of annectent reinforcing bars and the friction efficient between slip layer and masonry unit are chosen to investigate the differences of OOP mechanical behaviors. The results show that the horizontal sliding layers reduce the integrity of URM walls in reinforced concrete frames, causing the constraint of surrounding frame on infilled wall and the arching effect inside infilled wall become weaker, and OOP bearing capacity to drop. It is found that i) the annectent reinforcing bars is conducive to reducing the out-of-plane failure of the wall; 2)the smaller the slip layer spacing of the wall is, the more serious the damage of the infill wall under the out-of-plane load is, and the smaller the out-of-plane bearing capacity and the out-of-plane stiffness of the wall are; iii) the influence of the friction coefficient between slip layers and masonry unit on OOP mechanical behaviors is small. Finally, Chinese building design code is also selected to estimate the OOP bearing capacity of URM walls with horizontal sliding layers. The value of λcr is recommended to be greater than 1.0, and the value of λP is greater than 3.3. The spacing of the slip layer should be greater than 1 / 5 of the wall height, and the length of the annectent reinforcing bars should not be less than 1 / 5 of the infilled wall length.

Integrating Sonic Pulse Velocity Tests with Masonry Classification for Heritage Conservation: An Insight from On-Site Diagnostic Campaigns

ABSTRACT The preservation of architectural heritage relies on a comprehensive understanding assisted by diagnostic procedures. Among non-destructive techniques, the Sonic Pulse Velocity Test (SPVT) qualifies the compactness of a masonry wall through elastic wave transmission. However, it does not directly estimate any mechanical parameters. This study presents findings from a database of 346 direct SPVTs carried out over thirteen years on both listed and ordinary buildings. Results were categorized based on masonry type according to the Italian building code, to derive information about construction quality and relate SPV with building features. Tests performed on 37 masonry panels strengthened by grout injections also confirmed the validity of SPVT in evaluating the effectiveness of the intervention. Furthermore, the Masonry Quality Index (MQI) method permitted to refine the masonry type definition through the judgment of the units’ arrangement. MQI and SPVT results were also combined by statistical analysis. These findings aim to increase comprehension of the different types of existing masonry capacity and contribute to engineering assessments for ensuring the structural safety of historical buildings.

A rapid method to census the seismic risk class of masonry buildings

Ministerial Decree 65/58 and its Guidelines, published in 2017, allow the seismic risk classification only of masonry buildings, associating with their vulnerability class their location within the four seismic zones into which Italy has been divided since 2003. Therefore, if the masonry type and structural weaknesses of a building are known, it is possible to assign the corresponding vulnerability class to it and to census, by means of a rapid onsite survey, the seismic risk class of a very large number of masonry buildings. Based on this assumption, a method has been developed for a single operator to rapidly determine the masonry type and structural weaknesses of a building. The survey was conducted by recording this information in alphanumeric tables divided into fields whose attributes were preliminarily chosen and inserted in data dictionaries that could be brought up with drop-down menus. At the end of the survey, the contents of the tables were transferred to a relational database, incorporated in a geographical information system, filtered and processed to obtain the vulnerability class of each building represented on the same basic numerical cartography used during the survey. By associating the seismic zone with the building, the corresponding class was calculated. The method made it possible to census the seismic risk class of 400 masonry buildings in a municipality with an extension of ca. 20 km2 in less than two working days. This highlights the possibility of extending it to larger areas to estimate, assess or manage the effects or the emergency phase of an earthquake.

Damage detection of a typical historic masonry tower using control charts

Damage detection of a typical historic masonry tower using control charts

TRM strengthening as effective prevention against premature failure of masonry walls

Masonry structures are very prone to cracking and premature failure in the presence of shear loading. Therefore, effective prevention of their premature damage is needed. This paper presents laboratory tests of small models made of autoclaved aerated concrete (AAC) blocks, which were externally reinforced using two different strengthening sets consisting of mortar and mesh, and subjected to diagonal compression. The experiments used a commercialised system designed for the strengthening of typical masonry substrates (brick, stone) and a low-cost and lowstrength mesh and mortar set used as part of a system for insulating buildings. The analyses presented are of a comparative nature and describe changes in the behaviour of the models depending on the strengthening set used. The application of full-surface strengthening clearly changed the behaviour of AAC walls from brittle one to the ‘pseudo-ductile’ one observed after the appearance of the first cracks. In all strengthened models, a significant increase in the load capacity (from 3% to 62%) and a post-peak phase were reported. An interesting finding was the high efficiency of nonstructural materials (plastering system), comparable to the effects of the use of commercialised system solutions. This strengthening can be successfully considered as an effective preventive action. Finally, a simplified method is provided to calculate the contribution of the strengthening to the load bearing capacity of the strengthened models. The method defines the effect of the mesh and the mortar independently, based only on the basic material properties of these two components.

Development of mechanics-based fragility curves for the Italian masonry school asset

This article presents the derivation of a fragility model for the Italian masonry school building asset, comprising 265 sets of fragility curves for as many building types, classified on the basis of few parameters: construction age, number of stories, plan area, and type of masonry (i.e. with regular or irregular pattern). The fragility assessment was carried out by means of parametric analyses, generating more than 7500 samples which were then analyzed through the mechanics-based procedure Vulnus. Sample fragilities were then linearly combined to obtain fragility curves consistent with the adopted taxonomy based on few parameters. A macroseismic–heuristic model from the literature was used to extend the fragility model to five damage states, according to the European Macroseismic Scale (EMS98). The proposed model was compared to empirical information in terms of observed damage on three existing schools and fragility curves recently derived by processing data of school damaged by the 2009 L’Aquila earthquake, showing a satisfactory agreement. In addition, a comparison with fragility sets for residential buildings was carried out. Both fragility models were developed with the same procedure, so as to point out differences between schools and ordinary buildings. Similar fragilities were observed for schools and residential buildings built before 1945, whereas for later periods, schools showed a higher fragility than the residential asset. Finally, seismic damage maps were developed at national scale showing the distribution of expected damage as a possible application of the derived model.

Seismic hazard models for typical urban masonry structures considering optimized regression algorithms

Seismic hazard models for typical urban masonry structures considering optimized regression algorithms

Toughness of Natural Hydraulic Lime Fibre-Reinforced Mortars for Masonry Strengthening Overlay Systems

Masonry structures are susceptible to damage and collapse due to seismic actions, a problem in many urban areas. To address this issue, researchers are studying the use of fibre-reinforced mortars as overlay strengthening systems. This study assessed the use of synthetic polyacrylonitrile (PAN) fibres as reinforcement of natural hydraulic lime mortar, focusing on their influence on fresh behaviour and mechanical properties. Natural hydraulic lime (NHL) was chosen for its compatibility with typical older ceramic and natural stone structural masonry and contemporary ceramic brick infill masonry substrates, as well as for the sustainability benefits. The study also assessed the contribution of the PAN fibres to toughness enhancement in the developed formulations. The fresh behaviour of fibre-reinforced mortar (FRM) was found to be adequate for applications with fibre volume fractions below 0.50%. The compressive and flexural strengths were affected differently by the increase in fibre volume fraction, with compressive strength decreasing and flexural strength increasing. The maximum compressive strength of 13.3 MPa was obtained for 0.25% of fibres, while for flexural strength a maximum of 6.70 MPa was achieved with 1.00% of fibres. The compressive and flexural toughness, related to the post-cracking responses, increased with the fibre fraction, and even for fractions as low as 0.25%, an important increment of the capacity to dissipate energy was achieved.

Damage Evaluation and Seismic Assessment of a Typical Historical Unreinforced Masonry Building in the Zagreb 2020 Earthquake: A Case Study—Part I

The city of Zagreb, the national capital and economic hub of Croatia, is situated in a seismically active region and hosts a significant array of historical buildings, from the medieval to Austro-Hungarian periods. These buildings possess varying but generally high degrees of vulnerability to seismic loading. This was highlighted in the Zagreb earthquake of 22 March 2020, emphasizing the need for seismic retrofitting in order to preserve this architectural heritage. In this paper, the seismic capacity of one such unreinforced masonry building is considered through a number of analysis methods, including response spectrum, pushover, and out-of-plane wall failure analyses. Given the advantages and disadvantages of the individual methods, their applicability and value in a seismic analysis is considered. Ambient vibration measurements before and after the Zagreb 2020 earthquake, used for model calibration, are also presented. Conclusions are drawn from each individual analysis and later compared. In conclusion, no single analysis method considers all relevant failure modes, and a combination of nonlinear static or dynamic analysis and out-of-plane analysis is recommended. Due to the large volume of the material, it is published in two parts, with ground motion record selection, dynamic analysis, and a comparison of the results published in part two.

Various numerical modeling procedures of XIX-century masonry building

The 2020 Croatian earthquake marked a new phase in the assessment of existing buildings throughout the region and especially in the ex-Yugoslav countries, specifically in Bosnia and Herzegovina. This was the first time that a database of 700 buildings in Sarajevo was conducted with the aim to perform a rapid seismic vulnerability assessment. Several buildings were identified, as typical representatives of a certain period, and a detailed numerical assessment was performed. The study systematically investigated the seismic response of a typical masonry building from the Austro-Hungarian era in Sarajevo in the modeling scenarios with diverse horizontal diaphragm typologies. Conventional structures with inferior workmanship and substandard materials in horizontal diaphragms exhibited reduced seismic performance. It was established that the diaphragm’s ability to enhance the seismic behavior of such buildings is dependent upon its stiffness and its connection mechanism to load-bearing walls. Comparative analysis of models, particularly Total Strain Crack Models (TSCMs) and the Engineering Material Model (EMM), clarified distinct behaviors in terms of load capacity and ductility. The investigation considers the building’s resistance to seismic forces in both X and Y directions and explores damage patterns, failure modes, and crack distributions. The type of slab connection emerged as a crucial factor, significantly influencing stiffness, capacity, and ductility. These insights offer valuable implications for retrofitting strategies, enabling precise identification of diaphragm components for targeted strengthening and, consequently, enhancing a structure’s seismic resilience. A comprehensive site investigation and accurate determination of connection types were underscored as crucial prerequisites for effective building modeling, essential for earthquake impact assessment, and informed retrofitting decisions.

Study of Rapid Evaluation Method for Structural Load‐Bearing Capacity of Typical Rural Masonry Residential Buildings in Shandong Province, China

Typical rural masonry residential buildings mainly include brick–wood and brick–concrete structures, and they occupy a significant proportion among individual buildings in Shandong Province, and their structural reliability directly affects the safety of life and property. Structural load‐bearing capacity can be used for quantitative judgment of structural reliability level. For evaluating the structural load‐bearing capacity of rural masonry residential buildings rapidly, factors affecting the structural bearing capacity and positions with weak structural bearing capacity are determined by field investigation and modeling analysis with software for structural calculation. The ratio of structural resistance to action effect is taken as the evaluation index of structural bearing capacity, and the quantitative relationships between this index and the masonry compressive strength, mortar strength, window–hole ratio, and the cantilever width are established through regression analysis. The accuracy and applicability are verified by Elman neural network model as well as comparison results between rapid evaluation formula and modeling analysis. The results show that the rapid evaluation model for structural load‐bearing capacity in this paper can be used to accurately describe the relationships between the ratio of structural resistance to action effect with affecting factors, and it can play a role in screening structural monomers with irregular load‐bearing capacity in group evaluation of structural bearing capacity.

Soil-structure interaction effects on out-of-plane seismic response and damage of masonry buildings with shallow foundations

A significant amount of damage and casualties induced by several strong-motion earthquakes which recently stroke South-East Mediterranean area is due to the major seismic vulnerability of residential buildings. In small villages and mid-size towns, those buildings very often consist of two- to four-story, unreinforced masonry (URM) structures not designed for earthquake resistance, with direct foundations usually corresponding to an in-depth extension of load-bearing walls. For such structures, especially when founded on soft soils, site amplification and soil-foundation-structure interaction (SFSI) can significantly affect the seismic performance; conversely, such phenomena should be investigated through methods that allow a trade-off between accuracy and computational effort, hence encouraging their implementation in engineering practice. This paper provides a comprehensive updated description of the studies carried out in the last years by the authors, which are based on both linear and nonlinear, parametric, dynamic analyses of complete soil-foundation-structure (SFS) models representative of existing residential building configurations on different soils. Specifically, the parametric study investigated SFS models with different masonry types, aspect ratios, and code-conforming homogeneous and heterogeneous soil profiles. The methodology and analysis results allowed for reaching the following objectives: (i) predicting the elongation of the fundamental period and the variation of equivalent damping of the SFS system with respect to fixed-base conditions, through a simplified approach based on an equivalent simple oscillator; and (ii) estimating the probability of exceeding increasing damage levels associated with out-of-plane overturning of URM walls, through fragility functions that take into account SFS interaction. The effectiveness of these simplified tools was successfully validated against well-documented case studies, at the scales of both single instrumented buildings and urban area.

A Review of Various Masonry Blocks Employed in Wall Construction

This comprehensive review explores the diverse range of masonry blocks commonly utilized in contemporary wall construction. It aims to provide insights into the various types of masonry blocks available in the construction industry, their characteristics, applications, and advantages. By examining these materials in detail, this review contributes valuable information to architects, engineers, builders, and construction professionals, assisting them in making informed decisions about the selection and use of masonry blocks in their projects. Additionally, the abstract may summarize the key findings, trends, and considerations discussed in the full review.

How fragile are buildings in Bosnia and Herzegovina once exposed to earthquake motion?

The 2020 earthquakes that hit the Croatian capital city Zagreb and Petrinja revealed the (un)preparedness of the country once exposed to strong earthquake motion. Three years after, numerous buildings out of 25,000 that have been heavily damaged and destroyed still have not been reconstructed. The effect of the earthquake was felt as well in the bordering cities and towns in Bosnia and Herzegovina (BIH). Seismic assessment of the existing buildings in BIH is done by individual researchers and there is no defined methodology not policy for such activities. This paper aims to present the work that has been done in this field up to now and to give guidelines for the further work that needs to be conducted. The starting point was the calculation of the earthquake risk for the entire Bosnia and Herzegovina based on the rapid assessment taking into account the vulnerability of buildings, seismic hazard, and population exposure. A more detailed assessment was conducted for the three largest cities in BIH, specifically Sarajevo, Banja Luka, and Tuzla. Typical residential masonry structures were identified, and detailed calculations were conducted, leading to the need for their strengthening. To have a more detailed picture much work has to be conducted.

Seismic damage analysis of a brick masonry loess cave by a shaking table and FEM

In this paper, a typical brick masonry loess cave (BMLC) is selected, and finite element analysis software is used to establish a model and analyse its seismic performance. The model was verified by the test results of the BMLC on a 3D shaking table, and the damage quantification index was proposed. On this basis, seismic vulnerability analysis was carried out. A method based on nonlinear incremental dynamic analysis (IDA) was proposed to solve the rapid damage assessment of the traditional building of BMLC structures after earthquake action. The proposed method relies on an accurate numerical finite element model and pre-run multidimensional nonlinear IDA simulations with vibration data recorded during earthquakes. The IDA curves were built with different positions of the BMLC structure being considered. Moreover, meaningful local damage parameters were correlated with relevant seismic intensity measures. The results showed that the proposed method immediately and accurately estimated damage after seismic action if the IDA curve set had been previously constructed using a suitable model.

Characterization of mechanical behavior of different types of masonry with a detailed investigation of full-field strain using digital image correlation

This article presents an experimental study on the mechanical characterization of three different types of masonry: burnt clay bricks, fly ash bricks, and autoclaved aerated concrete (AAC) blocks, with a detailed focus on strain distribution and failure mechanism. The specimens were subjected to direct and diagonal compression loading, and the stress–strain curves and failure modes were studied. Digital image correlation (DIC) was used to obtain full-field strain data, allowing for detailed analysis of failure mechanisms, tracking of crack propagation, and examination of other intricate details. The DIC analysis showed that in burnt clay brick and fly ash brick masonry, failure under compression was initiated by the tensile splitting of the brick, while in AAC block masonry, it was initiated by the tensile splitting of the mortar. Additionally, the study identified that the failure modes under diagonal compression were different for each type of masonry, with bed joint sliding being the dominant failure mode in fly ash brick and AAC block masonry. In contrast, the failure mode in burnt clay brick masonry was due to vertical splitting along the loaded diagonal. In the diagonal compression test, the shear strain along both diagonals was negligible, and principal strain directions were observed to be aligned along the two diagonals.