Brick Masonry Structures Research Articles

Testing Methods for Masonry Cores: A way forward to increase reliability of mechanical properties evaluation

The assessment of unreinforced brick masonry structures and infrastructure is a worldwide challenge for the development of resilient urban areas and preservation of historical assets. Among other factors, the estimation of mechanical performance of masonry in existing construction is of importance. However, the characterisation effort does not always satisfy the requirements from structural analyses point of view, i.e. need of elastic, strength and toughness properties, and/or from technical point of view, i.e. use of conventional technical expertise and limited invasiveness. In this respect, the new RILEM Technical Committee CTM aims at promoting the use of tests on masonry cores for the evaluation of compression and shear properties of unreinforced masonry with regular units. Upon a state-of-the-art review, a database of previous experimental test series will be created to identify influencing factors (e.g., core’s geometry, boundary conditions). Selected testing procedures will be compared at various international institutes for a variety of masonry types typically used in existing structures and infrastructure. By comparing results with standardise tests, correction factors will be identified. Eventually, testing guidelines to characterise masonry with core specimens will be defined and shared within the research and engineering community.

Numerical simulation of behavior of masonry mechanics made with ecological bricks

Soil-cement brick masonry structures have gained prominence in developing countries due to their practicality, low cost and excellent ecologically sustainable alternative. However, the literature presents few numerical studies on masonry structures in soil-cement bricks, since most of the studies carried out focus on concrete and ceramic bricks. Therefore, in this work, the finite element model of a small wall made of soil-cement brick with structural masonry mortar joints, subjected to compression, is calibrated. The experimental analysis of these small walls was conducted at the Laboratory for Experimental Analysis of Structures at the Federal University of Minas Gerais, and the experimental results are used to calibrate the numerical simulation. The numerical model was developed in the finite element program ABAQUS CAE. A detailed micromodeling strategy was adopted, that is, the models were developed considering the individual representation of bricks and mortars, in addition to the interface between the materials. Using the proposed finite element model, a numerical investigation was conducted to verify the validation of the model concerning experimental investigations. The present study allowed us to adequately replicate the concentration of damage in the bricks, corroborating what was observed in the experimental tests.

Maximum shear analysis of clay brick masonry structures for advanced design with bamboo diagonal reinforcement

Abstract The traditional rural houses in Indonesia, constructed with clay brick masonry wall, lack the usage of detailed reinforced concrete frame. Therefore, in the event of an earthquake, numerous structures made of masonry walls experience a collapse. Clay brick masonry walls require alternative reinforcement that is both accessible and readily available, such as bamboo, which is abundant in rural regions of Indonesia. The objective of this study is to analyse the behaviour of wall collapse under lateral stresses and assess the potential for enhancing the wall’s shear strength through the use of bamboo diagonal reinforcement. Bamboo is expected to be more advantageous for low-cost construction, replacing steel, particularly in the rural regions. The test findings are examined and inferences are made for the subsequent analysis phase. The analysis conducted involves the modelling of clay brick masonry walls, both with and without bamboo diagonal reinforcement, using the acquired data on material properties. The inclusion of bamboo diagonal reinforcement results in a 9.57% reduction in the principal stress at maximum normal stress.

Heritage clay brick characterization and assessment with compatible contemporary bricks for retrofitting of heritage monuments

Various mughal architecture clay brick masonry monuments were built in the Punjab state of northern India from the late 14th to late 19th centuries. Nanakshahi monuments (era of 1st Sikh Guru-Guru Nanak Dev Ji) are gigantic clay brick masonry structures constructed of lime and lime surkhi mortar (a powdered form of red burnt clay brick). Currently, this study is focused on identifying a suitable material for repairing and strengthening heritage clay brick monuments. Using the mineralogical composition of heritage Nanakshahi clay bricks (NSCB), the study compares them with contemporary clay bricks (CCB) from the same region, and then compares them to newly prepared clay bricks (NPCB), which have similar composition and dimensions to NSCB. The X-ray fluorescence confirms that the NSCB samples of southeast Punjab have an elemental composition consisting of filler SiO2 and binding elements like Al2O3, Fe2O3, CaO, K2O and MgO. The average density of ancient NSCB and CCB has been found to be similar; the ancient NSCB has a lower water absorption rate and porosity in contrast to the present-day clay bricks. The Initial rate of absorption of an ancient NSCB is quite higher. In comparison to the heritage NSCB, the CCB's compressive strength value is lower and uniaxial compression strength of newly prepared clay bricks (NPCB) of similar mineralogical composition and dimensions is comparable to that of the heritage NSCB from Punjab districts. The significance of the study is to suggest a compatible material for strengthening of heritage clay brick monuments of northern India.

Numerical Investigation of the Properties of Japanese Historical Brick Masonry Structures

Numerical Investigation of the Properties of Japanese Historical Brick Masonry Structures

Crack Evolvement of Ancient Brick Masonry Under Uniaxial Compression Fatigue Loading

ABSTRACT Cracking is an essential intuitive indicator of damage in masonry structures. Evaluating the progression of fatigue cracks in ancient brick masonry structures is vital for the preservation and safety of ancient buildings. By conducting amplitude cyclic uniaxial compression tests on ancient brick masonry specimens, using the video image correlate-3d (VIC-3D) technology to collect images of the entire process from loading to failure, the development of fatigue cracks is analyzed and concluded. A reversed S-shaped function for fatigue crack evolution was established based on the fatigue damage mechanism. The model parameters’ physical significance, value range, and their impact on the model curve were discussed. The fatigue damage evolution equation was derived from the fatigue crack evolution model. The research results show that a reversed S-shaped function for fatigue crack evolution covers various types of fatigue crack evolution laws, with strong adaptability and high accuracy. The damage evolution curve established, based on the fatigue crack evolution model, has a reversed S-shaped change rule, and was divided into three stages: the first stage (0 N f ~ 0.1 N f ) fatigue damage grows faster; the second stage (0.1 N f ~ 0.9 N f ) fatigue damage growth is stable, close to linear change; when the cycle ratio exceeds 0.9, it enters the third stage, and fatigue damage increases rapidly.

Damage assessment method of clay brick masonry load-bearing walls under intense explosions with long duration

The vulnerability of clay brick masonry load-bearing (CBML) walls under low-intensity explosions has been extensively investigated. In recent years, large-scale explosions have raised wide concerns about the destructive effect of intense explosions. Intense explosions induced by large TNT equivalent explosives usually cause severe damage to building structures within several kilometers. Although the damage of building structures under intense explosions and normal low-intensity explosions might be different, the differences have yet received any attention in previous studies. Therefore, this study numerically investigates the dynamic performance of CBML walls under intense explosions with long duration (IELD). Firstly, the numerical model is validated by reproducing experimental records. Then the verified model is utilized to investigate the dynamic response and dynamic modes of CBML walls under IELD. Based on the identified failure mechanism, the effects of several parameters such as axial compression ratio, compressive strengths of masonry materials and wall geometry on the damage degrees of CBML walls are analyzed in detail. The damage index based on the residual axial loading capacity of CBML wall is proposed for damage evaluation. The damage assessment method is established for CBML walls under IELD, which can help to evaluate the damage level of clay brick masonry structures under far-field intense explosive scenarios.

Collapse of the Dharahara Tower During the April 25, 2015 Nepal Earthquake: A New Interpretation Based on Video-Camera Footage

ABSTRACT Among the various important monuments impacted by the April 25, 2015 Mw7.8 Nepal earthquake, the Dharahara Tower located in Kathmandu suffered complete collapse. The collapse of the tower, a slender 60-meter-high old brick masonry structure with an almost cylindrical hollow shape, was captured by a low-quality video camera, which nonetheless helped to identify the critical moments. Initially, the tower descended more than 10 m vertically after a rupture at the base. After a few seconds, it overturned, disintegrating upon impact on the ground. At a distance of 1.3 km, an accelerometric station recorded the strong motion which was used as input of a discrete element model of the structure. Mechanical properties were taken from lab tests made on similar building materials. The Dharahara Tower had previously been analysed by other researchers using various methods. However, since they were apparently not aware of the mechanism observed in the video footage, their collapse models do not agree with this new evidence. For the initial phase of the collapse, the present model explains with great accuracy the observations of the video footage, but the final phase is dependent on various details, and modelling is not so robust.

Development of structural type-based physical vulnerability curves to debris flow using numerical analysis and regression model

Urbanization has significantly increased the risk of debris flows to houses located at mountain boundaries, particularly in South Korea, where urban centers are surrounded by mountains. The degree of damage to a house strongly depends on the structural rigidity of the building, even when exposed to the same hazard intensities. However, the structural characteristics of buildings are usually disregarded in vulnerability assessments. In this study, vulnerability curves were proposed for three different structural types of buildings: brick masonry, light-weight steel frame, and wood structures, using numerical and regression analyses. A total of 22 debris flow events from 2011 to 2020 and 63 cases of damage to unreinforced structures were collected and analyzed. Back analysis of the debris flows was performed using Flow-R, and the impact pressure acting on each structure was calculated. Three different vulnerability curves were proposed using various linear and nonlinear regression analyses; the Avrami equation provided the highest statistical significance. The vulnerability curves of three different structures were similar for the slight damage range. However, over the slight damage range, the wood structure was the most vulnerable at a given hazard intensity, whereas the brick masonry structure was the least vulnerable. Validation was performed using data from recent debris flow events, revealing precise damage level predictions for 9 out of 11 buildings. Compared with previous research, the degree of damage at the same hazard intensity was found to be significantly dependent on the structural type. The developed vulnerability curve for each unreinforced structure can be used as key data for vulnerability and risk assessments.

Improving the Efficiency of a Novel Controlled-Sliding-Based Isolation System for Brick Masonry Structures

Improving the Efficiency of a Novel Controlled-Sliding-Based Isolation System for Brick Masonry Structures

PLAXIS 3D numerical analysis of complex geotechnical problems of colossal built heritage

The paper aims to contribute to the preservation of high valuable historic masonry structures and historic urban landscapes through the combination of geotechnical, structural engineering. The main objective of the study is to conduct finite element analysis (FEA) of bearing saturated soft clay soil problems and induced structural failure mechanisms. This analysis is based on experimental and numerical studies using coupled PLAXIS 3D FE models. The paper presents a geotechnical analytical model for the measurement of stresses, deformations, and differential settlement of saturated clay soils under colossal stone/brick masonry structures. The study also discusses the behavior of soft clay soils under Qasr Yashbak through numerical analysis, which helps in understanding the studied behavior and the loss of soil-bearing capacity due to moisture content or ground water table (G.W.T) changes. The paper presents valuable insights into the behavior of soft clay soils under colossal stone/ brick masonry structures. The present study summarized specific details about the limitations and potential sources of error in Finite Element Modeling (FEM). Further field research and experimental analysis may be required to address these limitations and enhance the understanding of the studied soft clay soil behavior. The geotechnical problems in historic monuments and structures such as differential settlement are indeed important issues for their conservation since it may induce serious damages. It deserves more in-depth researches.

An Experimental and Numerical Investigation of an Unreinforced Brick Masonry Structure Subjected to Base Excitation

An Experimental and Numerical Investigation of an Unreinforced Brick Masonry Structure Subjected to Base Excitation

Seismic behavior of the brick masonry rural building strengthened with polypropylene grid cement mortar coating: Shaking table tests

Brick masonry structures are widely applied around the world, especially in Chinese rural areas, but their seismic performance is not satisfactory due to high brittleness of material and poor integrity of structure. Accordingly, a low-cost and highly efficient strengthening method for brick masonry structure is needed. This paper presents the shaking table tests for a 1/2-scale single-story brick masonry rural building strengthened with polypropylene grid cement mortar coating. The damage states of the test model under earthquake motions with different intensity were observed. The dynamic characteristics including natural frequency and damping ratio were discussed. The seismic response, such as acceleration, displacement, torsion angle, base shear and hysteretic energy dissipation, were analyzed. The results show that the weak areas of the test model were the corners of windows and door, the intersections between longitudinal wall and transverse wall and the top of longitudinal walls. With the input PGA of 1.0 g, the natural frequencies of the test model in the X and Y directions decreased to 93.1 % and 88.2 % of the initial values, respectively, the damping ratio in the X and Y directions increased to 2.56 and 1.61 times the initial values, respectively, and the maximum story drift and horizontal torsion angle were 1/122 and 0.0037 rad, respectively. The comparison between actual earthquake damage and test results showed that the use of polypropylene grid cement mortar coating to strengthen brick masonry rural building could result in good seismic behaviors.

Mesoscale analysis of fracture process in brick masonry structures

This paper deals with mesoscale analysis of masonry structures, which involves fracture propagation in brick units as well as along the masonry joints. The brick–mortar interfaces are incorporated in standard finite elements by employing a constitutive law with embedded discontinuity. Macrocracks in bricks are modelled in a discrete way using the same methodology, without any a-priori assumptions regarding their orientation. The proposed approach is computationally efficient as it does not explicitly require the discretization of joints. The accuracy of the approximation is first assessed by comparing the solution with a detailed mesoscale model incorporating interface elements. Later, a numerical study is conducted involving simulation of various experimental tests on small masonry assemblages, as well as single-leaf masonry walls, with running bond pattern, subjected to in-plane loading. The results clearly demonstrate the predictive abilities of the proposed simplified approach.

An analytical model for determining realistic tensile strength and fracture toughness of fired clay bricks

The crack resistance of fired clay bricks is crucial for the safety design of brick masonry structures and needs to be evaluated reasonably. However, the realistic fracture parameters are extremely difficult to predict owing to the porous and defective characteristics of bricks. Thus, this paper aims to determine the tensile strength (ft) and fracture toughness (KIC) independent of size for fired clay bricks, which are rarely reported in previous studies. The fracture mechanisms of the bricks were elucidated using the fracture tests on brick specimens having varied sizes and notch lengths. Considering the material heterogeneity and discontinuity, the maximum fracture load (Fmax) correlates linearly with ft and KIC according to boundary effect model. ft and KIC can be predicted directly once only Fmax is determined from the test. The results showed that the predicted ft and KIC were generally independent of notch length and specimen size. Using statistical analysis, the means and upper and lower limits of ft and KIC were determined. Moreover, the predicted ft and KIC of bricks proved to be suitable for recycled brick aggregates with particle sizes of 5–40 mm. Thus, the crack resistance of the brick aggregates was clarified based on the proposed analytical model.

Development of Fragility Functions for Brick Masonry Structures Using Damage Data from September 24, 2019, Earthquake in Mirpur, Azad Kashmir

Development of Fragility Functions for Brick Masonry Structures Using Damage Data from September 24, 2019, Earthquake in Mirpur, Azad Kashmir

Out-of-plane flexural behavior of brick masonry strengthened with engineered cementitious composites embedded in the horizontal mortar joint

Unreinforced masonry (URM) structures exhibit high vulnerability under out-of-plane loads. Engineered cementitious composite (ECC) is suitable for the reinforcement of URM structures due to its excellent mechanical properties. This study presents a promising method to strengthen brick masonry structures using ECC embedded in the horizontal mortar joints. In order to investigate the flexural behavior of brick masonry strengthened by the proposed method under one-way horizontal bending loads, a total of nine groups of masonry specimens were tested under four-point bending loads, including one group of un-strengthened specimens and eight groups of ECC-strengthened specimens. The mix proportion and reinforcement ratio of the ECC were considered as variables in the experimental schemes. The failure mode, load–displacement curves, stiffness, strength, energy dissipation capacity, and ductility of the specimens were discussed. The test results demonstrate the effectiveness of this strengthening system in improving the out-of-plane performance of URM structures. The tensile properties of the ECC were closely related to the out-of-plane flexural behavior of the strengthened specimens. The flexural performance of the strengthened specimens generally improved as the tensile properties of the ECC increased. The maximum mid-span loads and corresponding displacements increased by 34%-171% and 33%-163%, respectively, compared to the control specimens. Furthermore, the flexural stiffness of the strengthened specimens was enhanced by a maximum of 63%. The flexural strength and energy dissipation capacity of the strengthened specimens increased with the reinforcement ratio of the ECC. The maximum flexural strength and energy dissipation capacity of ECC-strengthened specimens were 2.39 and 7.01 times higher than those of un-strengthened specimens, respectively. In addition, the results showed that the maximum bending moments of un-strengthened and strengthened specimens could be better predicted by the existing theoretical model.

Modelling the in-plane/out-of-plane interaction of brick and stone masonry structures using Applied Element Method

This research focuses on the numerical modelling of the seismic behaviour of unreinforced masonry (URM) structures with interconnected in-plane (IP) loaded and out-of-plane (OOP) loaded walls. The mechanical behaviour of such wall assemblies is complex and comparatively more challenging than that of isolated components, involving the interaction between interlocked orthogonal elements subjected to different load types. IP/OOP interaction phenomena are also challenging to model numerically, and their simulation is still relatively unexplored using the Applied Element Method (AEM) – the discrete simplified micro-modelling strategy employed in this paper. To fill this knowledge gap, the AEM is herein adopted to simulate the experimentally observed seismic behaviour of two URM building prototypes, one made of clay bricks and the other of stone blocks. The AEM models developed are calibrated and validated against previous experimental data, showing a satisfactory agreement between measured and numerical responses. In addition, a parametric study was performed using pushover analysis to investigate the influence of key material properties on the overall behaviour of the clay brick masonry specimen. The study suggests that the AEM models used in this study are suitable for conducting subsequent seismic assessment of URM structures with interlocked IP/OOP loaded walls, providing validated modelling strategies that can be useful to both researchers and engineering practitioners.

Experimental and DEM numerical analyses of the flexural and diagonal compression behavior of masonry reinforced with polyurea coating

The brick masonry specimens in this paper were strengthened with polyurea reinforcement before flexural and diagonal compression tests. The influence of one-sided and double-sided polyurea coatings on the load capacity and displacement were studied. According to the findings, the polyurea coating used for strengthening provided a considerable increase in load capacity as well as deformation. Two modeling approaches, macro-modeling and micro-modeling based on the Discrete Element Method (DEM), were applied. The Three-Dimensional Distinct Element Code (3DEC) program was used to simulate the behavior of the brick masonry. Several parameters, including joint-normal stiffness, joint-shear stiffness, and friction angle, were investigated, and their influence on the brick masonry structure was evaluated. The research determined that the prediction of ultimate load and behavior failure in the models could be predicted with accurate results. Furthermore, computational models were developed to compare against experimental tests. The results obtained from the simulation showed that the proposed modeling may be effectively used to verify the experimental results.

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

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