Behavior Of Brick Masonry Research Articles

Meso-scale numerical simulation of the mechanical behaviour of brick masonry in earth mortar

The paper discusses the mechanical behaviour of masonry composed of fired solid bricks and earth mortar. Such masonry is a typical construction technique in South and Southeast Asia. As its mechanical behaviour is complex due to high anisotropy attributed to noticeable difference in stiffness and strength between bricks and earth mortar, it is still considered challenging to comprehend the mechanical behaviour of such masonry. Taking into account this background, the present research addresses the formulation of the mechanical behaviour of brick masonry in earth mortar. Numerical analysis was performed to reproduce uniaxial compression and diagonal compression tests, referring to empirical evidences on interface behaviour between bricks and earth mortar. Meso-scale analysis was performed, applying a multi-surface failure criterion composed of cracking, shearing and crushing to unit-joint interfaces. The analysis showed very similar stress-strain relations and failure patterns to the tests. The simulation of the uniaxial compression test presented that the distributions of compressive stress shifted along with the progress of cracks. In the reproduction of the diagonal compression test, vertical stress was irregularly distributed after diagonal stepwise cracks appeared. Two comparative studies were conducted to examine the shear performance of brick masonry in earth mortar. First, sensitivity analysis indicated the noticeable influences of compressive strength, friction angle and facture energy of unit-joint interfaces. Second, macro-scale analysis was conducted, using a homogeneous material model. The observed diagonal crack patterns were similar to the test. The paper contributes to the understanding of the mechanical behaviour of brick masonry in earth mortar.

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.

Damage of Infill Masonry Walls due to Vertical Loads in Buildings with Reinforced Concrete Structure

Buildings are subjected to deformations of their reinforced concrete structure due to vertical loads that can lead, in certain cases, to the significant cracking of the unreinforced masonry (URM) infill walls, therefore requiring the development of specific knowledge of these types of deformations in order to minimise them. Aiming the evaluation of buildings with reinforced concrete structures subjected to vertical deformations, the mechanical characteristics of their infill masonry walls, as well as of their interface with the supporting concrete elements, are here analysed. The basic compression behaviour of brick masonry is assessed particularly through the previous analysis of a vertical compression test of a masonry specimen. The mechanical behaviour characteristics of the constituents (bricks, and mortar joints) are analysed to account for their influence on the compression behaviour of masonry infill, aiming particularly for the prevision of their cracking in case of vertical deformations of the supporting reinforced concrete (RC) elements. Based on that evaluation, the analysis of masonry walls subjected to vertical deformations of their supports is made through the assessment of the relevant characteristic behaviour of masonry wall-beam/slab assembly in case of vertical load. A general modelling approach of the behaviour of URM infills and the interaction with their supports is generally accessed. Finally, the preventive control of deformations of masonry wall-beam/slab assembly is discussed.

Compressive and shear behavior of brick masonry assemblages strengthened with polyurea coating: Experiment and DEM investigations

Over the last few years, a huge amount of effort has been spent on developing numerical models to improve knowledge of methods to strengthen concrete and brick structures under various conditions. This paper evaluated the ability of the Discrete Element Method (DEM) to accurately predict the mechanical behavior of brick masonry. Two different specimens were tested for compression and direct shear, with and without polyurea reinforcement of the brick masonry. Detailed numerical models of the brick masonry were generated using the commercial software Three-Dimensional Distinct Element Code (3DEC) to compare the laboratory test results against simulation for both cases. The numerical and experimental results were found to be in good agreement, which demonstrates the efficiency and stability of the DEM for simulating brick masonry behavior. Another purpose of this research was to evaluated the effect of parameters on the numerical model, including mesh size, material cohesion, friction, and dilation. These important findings can be used to calibrate material model parameters for strengthening brick masonry in the future. • The experiment of brick masonry assemblages with/without polyurea coating. • Both compression and direct shear tests were carried out. • Commercial software 3DEC was utilized to verify the experiment results. • Parametric studies for strengthening brick masonry assemblages were investigated.

Compressive Strength of Brick Masonry Confined with Glass Fibre Reinforced Polymer

Compressive strength is one of the key factors influencing behavior of brick masonry. Various traditional techniques can be used to increase the strength, stiffness, and ductility of unreinforced brick masonry. However, considerable mass and thickness will be added to the original structural element as a result of with both aesthetics and economy will be affected. In this study, behavior of brick masonry prisms confined with glass fibre reinforced polymer (GFRP) has been investigated. Various patterns of wrapping were adopted using polyester resin. Maximum Compressive strength and ultimate strain of GFRP confined prisms were compared with unreinforced prisms. Results obtained show a substantial increase in compressive strength of prisms when confined with GFRP-polyester and GFRP-epoxy.

Critical analysis on the use of the shove test for investigating the shear-sliding behavior of brick masonry

The shove test (ASTM Standard C1531) is an experimental technique aimed at studying the shear-sliding behavior of brick masonry. It can be executed according to various testing methods that differ in the way the vertical compression load is applied and in the way bricks and/or joints are locally removed for inserting jacks. One of the most critical aspects is the correct evaluation of the compressive stress state on the sliding brick. The objective of the present paper is to investigate the capability of the shove test in determining the shear strength parameters of brick masonries and to highlight the main advantages and disadvantages of the various testing methods. To this aim, nonlinear numerical simulations of the shove test were performed by adopting a brick-to-brick modeling strategy. The 2D numerical model was calibrated and validated through comparisons with experimental results of triplet tests and shove tests. The numerical analyses allowed to understand the influence the different testing methods and the masonry mechanical properties, such as dilatancy, may have on the test results. Based on the numerical outcomes, correction factors were calibrated for the proper evaluation of the compressive stress state on the sliding brick. Improvements with regards to the experimental procedures, i.e. additional test phases and measurements, were also proposed to enhance the results interpretation.

Shear behavior of brick masonry strengthened with jute fiber reinforced composite

The unreinforced masonry is brittle and susceptible to sudden failure when subjected to lateral loads. The failures of unreinforced masonry in recent earthquakes have led to the development of new strengthening techniques. In this context, fiber reinforced composites are emerging as alternatives for strengthening of structural walls. Number of studies is available in the literature on the shear behavior of brick masonry. The focus of the present study is to determine shear strength of brick masonry by reinforcing with jute fiber reinforced composites. The experimental results indicated that shear strength and stiffness is enhanced by reinforcing with jute fiber composites. The Jute fiber composites are also effective to prevent sudden failure of unreinforced masonry.

In-plane behavior of various brick bonds in masonry walls

An analytical investigation is carried out to evaluate the influence of brick bond types in in-plane behavior of brick masonry. Header, Stretcher, and English bonds are chosen for numerical simulation for in-plane loading. For numerical modeling, simplified micro-modeling approach is adopted using plasticity-based constitutive models. Three-dimensional nonlinear simulations for the brick bonds for various aspect ratios and pre-compression are carried out in this study. The lateral in-plane displacement control loading is applied for each model until the ultimate failure. The sum of observations highlights that there would be no variation in the elastic behavior of various brick bonds. However, nonlinear analyses highlight that there would be significant variation in the behavior of masonry bonds the diagonal cracking would govern the failure mechanism mostly.

Numerical and experimental investigation on mechanical and thermal behaviour of brick masonry: An efficient consumption of ultrafine fly ash

The study aims to investigate the impact of Ultrafine Fly Ash (UFFA) blended cement mortar in masonry prism and its failure mechanisms. Class C fly ash (CFA) and UFFA with optimum pulverization time of 120 min and replacement of 50% in cement mortar was examined. Masonry prism made of clay and fly ash brick are exposed for compressive and shear loads to test the real field scenario. UFFA mortar has more specific heat capacity (Cp) due to existence of finer particles. In real time, heat transferring of wall, the brick plays a dominant role on volume basis which balances the enhancement of Cp of mortar efficiently. Interestingly, 50% replacement of UFFA guarantees the additional strength of 8% and 33% over the conventional mortar and masonry prism respectively, due to its size reduction, irregular shape and greater interlocking of hydrated products. Experimental results have been validated numerically using ANSIS workbench 18.

Compression behaviour of brick masonry strengthened with Textile Reinforced Concrete (TRC) – A preliminary study

Masonry is one of the most widely used conventional materials throughout the world but its failure mainly occurs due to low tensile resistance. The main objective of this study is to observe the effectiveness of the relatively new construction material Textile Reinforced Concrete (TRC), in strengthening the brick masonry prism. In the present work TRC consisting of an overnight cementitious curing mortar (OCCM) along with alkali resistant glass textile which can resist high tensile stress is used for strengthening of unreinforced brick masonry. The technique adopted in this work is not time consuming and is also practically feasible. Tests were carried out to study the axial compressive behaviour of prisms strengthened with cast-in-place TRC overlays and pre-cast TRC laminae with varying reinforcement ratios. Detailed investigations were carried out to observe failure patterns and ultimate failure load. From observations, 4 ply TRC overlays were found to be more effective. Among all strengthening methods mortar bonded TRC laminae exhibited enhancement in terms of compressive strength. It is concluded that this technique may benefit many applications in the area of masonry retrofit.

Mechanical Behavior of Brick Masonry in an Acidic Atmospheric Environment

In order to evaluate the deterioration regularity for the mechanical properties of brick masonry due to acid rain corrosion, a series of mechanical property tests for mortars, bricks, shear prisms, and compressive prisms after acid rain corrosion were conducted. The apparent morphology and the compressive strength of the masonry materials (cement mortar, cement-lime mortar, cement-fly ash mortar, and brick), the shear behavior of the masonry, and the compression behavior of the masonry were analyzed. The resistance of acid rain corrosion for the cement-lime mortar prisms was the worst, and the incorporation of fly ash into the cement mortar did not improve the acid rain corrosion resistance. The effect of the acid rain corrosion damage on the mechanical properties for the brick was significant. With an increasing number of acid rain corrosion cycles, the compressive strength of the mortar prisms, and the shear and compressive strengths of the brick masonry first increased and then decreased. The peak stress first increased and then decreased whereas the peak strain gradually increased. The slope of the stress-strain curve for the compression prisms gradually decreased. Furthermore, a mathematical degradation model for the compressive strength of the masonry material (cement mortar, cement-lime mortar, cement-fly ash mortar, and brick), as well as the shear strength attenuation model and the compressive strength attenuation model of brick masonry after acid rain corrosion were proposed.

Core testing method to assess nonlinear behavior of brick masonry under compression: A comparative experimental study

This study investigates the applicability of the core testing method to assess the complete nonlinear behavior of masonry in compression. A comparative experimental approach was adopted performing compressive tests on cores and companion wallets. Via a correlation study on seven objects, including literature data, a one-to-one correlation for both compressive strength and Young’s modulus is obtained, while further studies are necessary to evaluate peak strain and compressive fracture energy. Thanks to its limited invasiveness and the capability of capturing the post-peak response with standard equipment, the core testing method can be regarded as a practical alternative to conventional slightly-destructive techniques.

Predicting Uniaxial Cyclic Compressive Behavior of Brick Masonry: New Analytical Model

AbstractA constitutive model for simulating the compressive response of unreinforced brick masonry subjected to cyclic loading is presented and discussed. The developed formulations are consistent ...

Experimental and Numerical Studies on Ultimate Load Behaviour of Brick Masonry

The present work brings out the studies on ultimate load behavior of brick masonry subjected to compression and shear-loading. The work composed of both the experimental and numerical investigations, aimed at contributing to the better understanding of the knowledge on the behavior of brick masonry structures under monotonic loading. Two brick masonry specimens have been tested up to ultimate load and the structural response in terms of the load, deflections and strains has been investigated. Due to the complexity, time and expense involved in the experimental investigations on brick masonry, limited number of experimental studies have been conducted and further, numerical studies have been carried out to simulate the experimental tests by suitably adopting the appropriate constitute models for the materials used. The responses and the failure load behaviour obtained from nonlinear numerical models developed are found to be in good agreement with the experimentally obtained results. The proposed numerical models can easily be adopted for further studies on the structural component made using brick masonry considering various geometric configurations, material disposition, loading conditions etc.

Experimental Determination of Statistical Parameters Associated with Uniaxial Compression Behaviour of Brick Masonry

In view of practical significance of the compression behaviour of brick masonry, this article discusses the evolvement of an experimental programme based on a survey of the literature. Also, it is known that large scatter is expected in the mechanical properties of masonry and studies characterizing these statistical variations are scant in India. Using the evolved experimental programme and results of tests conducted, the statistical parameters, namely mean and coefficient of variation (COV) associated with the uniaxial compression behaviour of typical brick masonry used in South India have been determined in this article. For the masonry considered in this study, the mean values of peak compressive stress, strain corresponding to peak stress and elastic modulus are 2.82 MPa, 0.009 and 0.4 GPa respectively. The corresponding values of COV are 0.15, 0.2 and 0.12 respectively. In addition, a trilinear curve has been suggested as an idealized stress-strain relation for the brick masonry used in South India.

Experimental Determination of Statistical Parameters Associated with Uniaxial Compression Behaviour of Brick Masonry

Experimental Determination of Statistical Parameters Associated with Uniaxial Compression Behaviour of Brick Masonry

Experimental assessment of an innovative strengthening material for brick masonry infills

The vulnerability of masonry infill walls has been highlighted in recent earthquakes in which severe in-plane damage and out-of-plane collapse developed, justifying the investment in the proposal of strengthening solutions aiming to improve the seismic performance of these construction elements. Therefore, this work presents an innovative strengthening solution to be applied in masonry infill walls, in order to avoid brittle failure and thus minimize the material damage and human losses. The textile-reinforced mortar technique (TRM) has been shown to improve the out-of-plane resistance of masonry and to enhance its ductility, and here an innovative reinforcing mesh composed of braided composite rods is proposed. The external part of the rod is composed of braided polyester whose structure is defined so that the bond adherence with mortar is optimized. The mechanical performance of the strengthening technique to improve the out-of-plane behaviour of brick masonry is assessed based on experimental bending tests. Additionally, a comparison of the mechanical behaviour of the proposed meshes with commercial meshes is provided. The idea is that the proposed meshes are efficient in avoiding brittle collapse and premature disintegration of brick masonry during seismic events.

Compressive behaviour of brick masonry triplets in wet and dry conditions

Mechanical behaviour of old masonry may differ from the theoretical one to a great extent, hence it needs to be properly evaluated for quantifying the safety and serviceability of real structures, in view of their rehabilitation and/or seismic reliability assessment. Among the factors affecting such behaviour, the presence of moisture, mainly from rising damp, plays a key role in the deterioration state of old masonry structures, owing to salt crystallisation, frost damage, etc. Besides, water presence in the material pores may also directly influence their mechanical properties (compressive and tensile strength, elastic modulus), due to the interactions with the pore surface, enhancement of crack propagation velocity and other mechanisms. Although the effect of water saturation has been investigated for clay-bearing rocks, ceramics and concrete, its consequences on the mechanical behaviour of brick masonry still requires in-depth elucidation. For this reason, in the present paper the compressive strength and Young’s modulus of fired-clay bricks, cement-based and lime-based mortars as well as masonry triplets are investigated, in dry and wet conditions. The results are interpreted in the light of the microstructural features of the materials, i.e., total voids amount and pores size distribution.

Simulation of Brick Infill and Effect of Openings on RC Frames Using ANSYS

An infill frame is defined as a dual system, which consists of bricks or concrete blocks filling the inter-planar voids between lower and upper beam and space between side columns of reinforced or steel frame. Despite the fact that infill enhances both strength and stiffness of the moment resisting frames; their role is ignored in the design due to insufficient knowledge of the composite behaviour of infill and frames. It is credible, that a major portion of the lateral load is shared by the infill. This paper deals with translating existing experimental data into analytical methods. To understand the behaviour of brick masonry, a G+1 structure was modelled in ANSYS and results were obtained. The present study is also aimed at finding the effect of openings in brick walls and captive column effect. When infill walls are omitted in the bottom storey, a soft storey is formed compared to stiffer stories at top. By response spectrum analysis it has been proved that the structural time period for frame with infill decreases by 2 to 3 times compared to frames without infill. The results showed that the soft storey building frame attracts 40% more shear force than frame excluding soft storey effect. The variation in time period at different mode shapes, with and without infill is presented in the paper. The phenomenon of captive column was replicated and formation of short column is shown in the pilot study.

Permissible Stress Level of Brick Masonry under Compressive Cyclic Loading

Laboratory tests revealed that the behavior of brick masonry under compressive cyclic loading is characterized by three distinct stress-strain curves. These three curves are termed as envelope curve, common point curve and stability point curve. The envelope curve is obtained by superimposing the cyclic peaks on the monotonic stress-strain curve. The common point curve is the locus of intersection points of loading and unloading curves of the cycles. If for the same cycle, the loading and unloading are repeated several times, the intersection points of loading and unloading paths will stabilize at a lower bound. The locus of these stabilized points (lower bound points) of all cycles form the stability point curve. Therefore, the stability point curve can be used as a measure for the allowable stress for masonry under cyclic loadings. The proposed cyclic allowable stress level is associated with the accumulation of residual (plastic) strain levels as a result of cyclic loading history. The permissible stress level was found to be about two thirds of the cyclic peak stress of the specimen.