Masonry Wall Panels Research Articles

Shear capacity of interlocking compressed stabilized earth block masonry panels

An experimental study was conducted to investigate the shear performance of reinforced and unreinforced interlocking compressed stabilized earth block (ICSEB) masonry wall panels. Forty-eight wall panels were fabricated using Auram 295 blocks and subjected to diagonal-compression. The influence of coir fibres, channel block, type of reinforcement (steel and bamboo) and arrangement (mesh and vertical) on wall shear behavior were studied. Cracking patterns, failure modes, load-deformation response and shear capacity were analyzed and discussed. The feasibility of using conventional masonry analytical equations in estimating the shear load capacity of wall panels was also evaluated. The test results demonstrated that wall panels without bamboo/steel reinforcement failed suddenly in a brittle manner and split into two parts, whilst bamboo/steel reinforced grouted wall panels behaved in a more ductile manner and remained intact after the failure, irrespective of presence of fibres. The incorporation of fibres effectively increased the shear load and deformation ability of wall panels, irrespective of the variables examined. The panels reinforced with steel/bamboo showed a significant improvement in shear load capacity of about 20.33% to 162.94% and in deformation capacity of around 48.47% to 258.29% when compared to the panels without reinforcement. The adopted analytical equations inaccurately predicted the shear capacity of wall panels.

Experimental investigation of size effect on unreinforced concrete brick masonry walls under in-plane shear loading

The size effect is one of the primary structural characteristics exhibited in reinforced concrete (RC) members in shear. Even though numerous studies have been conducted on masonry walls under shear, very few studies have been conducted that definitively answer whether a size effect exists for masonry walls. Diagonal compression tests on two groups of masonry walls with different dimensions were conducted to investigate the size effect on concrete brick masonry walls. A total of sixty masonry wall panels were tested. Five bed-joint mortar mix properties were used for each specimen. Test results showed that four failure modes were observed: diagonal tension failure, combined failure, sliding failure, and toe-crushing failure. In particular, the diagonal tension strength was significantly related to the specimen size. The larger specimen size led to a lower shear strength. Also, the shear modulus was highly dependent on the specimen size. Through experimentation, this study demonstrated that masonry walls exhibit a size effect. Moreover, the size effect is valid only in cases of diagonal tension failure. Based on the test results, this study revealed a correlation between diagonal tension strength and wall size. Lastly, the adequacy of the predictions was compared to the existing masonry codes.

Dynamic characteristics of stone masonry walls before and after damage: Experimental and numerical investigations

Seismic behavior of masonry walls has been heavily investigated, especially by means of laboratory experiments employing cyclic tests to determine the mechanical parameters and seismic capacity. Nevertheless, the dynamic properties of the tested walls often remain unknown, even though the nature of the seismic response is dynamic and profoundly affected by the structure's dynamic properties. This paper presents an investigation on the dynamic properties of three different masonry wall panels in healthy and damaged states, and examines if damage quantification via tracking the changes in dynamic properties is feasible. Ambient vibration and impact measurements are used for the dynamic identification of wall panels, before and after they are tested in reversed-cyclic in-plane shear-compression tests. The natural frequencies, damping ratios, and mode shapes of the walls are determined and compared to each other. Moreover, the damage progression and its effect on the dynamic features of the URM wall panel is investigated using a discrete element model of the benchmark wall that is validated in terms of the force-displacement response and damage pattern of the wall. The results of the study indicate that changes in natural frequencies and mode shapes are traceable, although it is difficult to infer damage quantification relationships from these changes. The outcomes of this study also highlight that numerical models verified with the nonlinear quasi-static behavior do not necessarily match the wall's dynamic behavior, and that more research is required to update nonlinear numerical models. Overall, the results contribute to the knowledge regarding the dynamic characteristics of masonry walls in healthy and damaged conditions, and to quantify the damage in masonry walls as well as the changes in their dynamic properties.

Failure mode dependent shear strength of unreinforced concrete brick masonry wall panels

This study conducted diagonal compression tests to propose the failure mode dependent shear strength for unreinforced concrete brick wall panels. The test variable was the bed-joint mortar mixing ratio. Six brick wall panels were manufactured for each variable, and finally thirty specimens were tested. The test results showed five failure modes in the unreinforced masonry wall panels: diagonal tension, combined, bed-joint sliding, toe crushing, and non-diagonal failure. Furthermore, the shear strength of unreinforced brick wall panels was highly dependent on the failure mode. Based on the test results, the shear strength is suggested according to each failure mode. Additionally, the shear modulus of concrete brick wall panels was suggested as half of the value presented in the current codes for masonry structures.

Experimental and Numerical Simulation of Effects of High Temperature on RC Frame Infilled with Sandwich Panel

This study investigated the structural behavior of reinforced concrete (RC) frames infilled with masonry walls and polyurethane (PU) sandwich wall panels at elevated temperatures. This study aims to assess the influence of temperature on the stiffness and load-carrying capacity of infilled frames, optimize the thickness of the sandwich wall panel, and compare the performance of masonry and sandwich infill systems. Analytical investigations were conducted using finite element analysis software (ABAQUS) to simulate the behavior of the frames at elevated temperatures and consider various configurations of skin thickness for PU sandwich panels. Experimental tests were performed to validate the analytical results. The frames were subjected to transient temperature conditions and uniform unit loads to evaluate their response. Experimental tests were conducted on RC frames infilled with masonry and sandwich-wall panels at elevated temperatures. The frames were subjected to static loading, and their deformations and failure modes were observed. The analytical study revealed that an increase in the skin thickness of the sandwich panel improved its temperature resistance, stress-withstanding ability, and displacement. A skin thickness of 0.45 mm was determined to be the optimal choice considering stress levels and economic factors. The infilled frame with the sandwich wall panel exhibited a 19.22% higher initial stiffness than the masonry wall panel in the experimental tests. The ultimate load-carrying capacity decreased by 17.86% in the infilled sandwich wall panel frame compared to the masonry infill system. The study provides valuable insights into the behavior of RC frames infilled with masonry walls and sandwich wall panels under elevated temperatures. The optimized thickness of the PU sandwich panel was determined by balancing the thermal resistance and the structural performance. The infilled frames with sandwich wall panels exhibited enhanced stiffness but slightly reduced ultimate load-carrying capacity compared with the masonry infill. These findings contribute to the understanding of thermal effects on building structures and can aid in the design and construction of more resilient and efficient buildings in the future. Doi: 10.28991/CEJ-2024-010-01-018 Full Text: PDF

Investigation of torsion in confined masonry structures originating due to unsymmetric openings

A detailed comparative study was carried out to investigate the impact of unsymmetric openings on the torsional resistance of confined masonry rooms constructed in highly seismic-prone regions. To investigate in detail, an experimental and numerical investigation was carried out. Confined masonry wall panels with and without openings were experimentally tested to study the reduction in stiffness/lateral load-carrying capacity of walls due to the provision of openings. Further, a three-dimensional masonry room was tested experimentally to determine the torsion induced due to openings in confined masonry rooms. It was observed that on the provision of unsymmetric openings in confined masonry rooms, torsion was observed causing a reduction in the load-carrying capacity. The same was also confirmed using numerical simulation where it was revealed that on the provision of unsymmetric openings, 10% reduction in lateral load carrying capacity was observed in the confined masonry rooms as compared to the room with symmetric openings. Similarly, a lesser difference (0.1 mm) in the displacements between two corners of the wall opposite to the applied load was observed in the case of the confined masonry room having symmetrical openings on opposite sides. Therefore, it might be concluded that in highly seismic-prone regions, the provision of symmetric openings or utilizing other means of manipulating in-plane wall stiffness should be considered to reduce the impact of torsion.

Experimental Research Studies on Seismic Behaviour of Confined Masonry Structures: Current Status and Future Needs

Confined masonry (CM) is a construction system that consists of loadbearing masonry wall panels enclosed by vertical and horizontal reinforced concrete confining elements. The presence of these confining elements distinguishes CM from unreinforced masonry systems, and makes this technology suitable for building construction in regions subject to intense seismic or wind activity. CM construction has been used in many countries and regions, and has performed well in past earthquakes. The purpose of this paper is to review experimental research studies related to the seismic in-plane and out-of-plane behaviour of CM structures. The authors identify the key design and construction parameters considered in previous research studies and perform statistical analyses to establish their influence on the seismic performance of CM walls. For the purposes of this study, the authors compiled databases of previous experimental studies on CM wall specimens, which were used for statistical analyses. Finally, the paper discusses research gaps and the need for future research studies that would contribute to the understanding of seismic behaviour and failure mechanisms of CM walls.

Experimental study on using steel wires via the NSM method to improve the behaviour of masonry panels

The use of masonry materials in load-bearing walls has a history of centuries. Many efforts have been made to overcome their poor structural strength; one such solution is the near-surface mounted method. In the present study, steel wires 2.5 mm in diameter were used as reinforcement in the near-surface mounted method to strengthen masonry walls. Compared to rival materials, steel wires enjoy such advantages as small dimensions, eliminating buckling damage, lower cost, and ease of installation. The objective of the study was to determine the feasibility of using wires in the near-surface mounted method and to identify the best wire arrangement. For the purposes of, eight masonry wall panels of 920 × 920 × 100 mm were constructed to investigate the effects of different steel wire arrangements on such panel properties as strength, load-bearing capacity, and wall pseudo-ductility. The results showed that steel wires placed along the wall in the diagonal direction had the best effects on improving the performance of the masonry wall panels. Experimental results confirmed the desirable effects of the steel wire in the near-surface mounted method. This is evidenced by a 21-fold increase in Load-bearing capacity, a 52-fold increase in energy dissipation, and a 17-time rise in shear modulus as a result of using the wires. The near-surface mounted method is an appropriate method to reduce damage to residential masonry buildings and to safeguard historical and cultural heritage monuments.

Structural Performance of Energy Efficient Geopolymer Concrete Confined Masonry: An Approach towards Decarbonization

Geopolymer concrete is preferred over OPC due to its use of energy waste such as fly ash, making it more sustainable and energy-efficient. However, limited research has been done on its seismic characterization in confined masonry, highlighting a gap in sustainable earthquake-resistant structures. Our study compares the performance of alkali-activated fly-ash-based geopolymer concrete bare frame and confined masonry wall panels with conventional concrete. Experimental results showed that geopolymer concrete bare frame has 3.5% higher initial stiffness and 1.0% higher lateral load-bearing capacity compared to conventional concrete. Geopolymer concrete confined masonry exhibited 45.2% higher initial stiffness and 4.1% higher ultimate seismic capacity than traditional concrete. The experimental results were verified using a numerical simulation technique with ANSYS-APDL, showing good correlation. Comparison with previously tested masonry walls revealed that GPC confined masonry has similar structural behavior to cement concrete masonry. This study demonstrates that geopolymer concrete made from waste energy such as fly ash is a sustainable and low-energy substitute for OPC concrete, particularly in highly seismic-prone areas, for a cleaner environment.

Confined masonry in seismic regions: Application to a prototype building in nepal

Confined Masonry (CM) has emerged as an economical and viable construction technique, which is practiced in many seismically vulnerable zones around the world. Despite having performed well during past earthquakes, many seismically prone areas such as Nepal are reluctant to adopt confined masonry as a reliable method of building construction due to limited number of works in understanding its behavior under earthquake loading in comparison to more accepted construction such as RC frame structures and even lesser number of works comparing the behavior of full-fledged building models. Also, modeling of CM buildings still is not commonplace. The objective of this study is to validate a numerical model with the experimental results and to compare the features of the confined masonry thus modeled from a validated process with reinforced concrete construction in terms of seismic behavior and cost of construction in the scenario of Nepal. To attain this objective, the finite element models are developed for confined masonry wall panels which are validated using experimental results from existing works of literature. Then finite element models of prototypical confined masonry and reinforced concrete buildings, using locally available material properties, were developed so as to study the behavior of both under seismic loading by performing pushover analysis and preparing fragility curves. Moreover, a parametric study is performed to study the influence of critical parameters on the overall behavior of the building models. Finally, with the help of the results obtained, CM building has been established as a technically and economically viable building practice in seismically vulnerable areas.

In-plane strength of masonry wall panels: A comparison between design codes and high-fidelity models

The susceptibility of masonry structures subjected to in-plane loads is determined by the failure mechanisms that might occur, which are governed by the material and geometric properties of the masonry. In practice, masonry walls are usually analysed using design codes, which are derived from analytical (code-based) methods. However, design codes may be overly simplistic and conservative, necessitating re-evaluation and modifications. This paper aims to compile and review various existing design codes for determining the in-plane strength of masonry walls and assess their validity when predicting masonry wall panels’ in-plane strength with different geometry and material properties. For this purpose, Monte Carlo simulations were used to vary the geometric and material properties of walls and understand how these affect their in-plane strength and failure mode. An extensive numerical investigation employing three-dimensional finite element (FE) analysis was also undertaken to better understand the influence of pre-compression, wall height to length ratio, and aspect ratio of masonry units on the in-plane force capacity of the masonry walls. First, a cyclic quasi-static test was utilized to validate the numerical model. The results from the numerical analysis were in good agreement with the experimental findings in terms of load vs drift curve and damage pattern. Following that, the numerical model was used to implement a parametric investigation. According to the findings, in-plane strength decreases as the aspect ratio of the wall increases. Pre-compression also influences the in-plane strength of the masonry wall and the brittleness of the failure. In-plane strength of the shear-controlled walls was higher than that of flexure-controlled walls. Failure mechanisms of walls were also extensively studied and a combination of failure mechanisms was observed. Also, the aspect ratio of masonry units was found to influence the failure mechanism of the wall. The comparison of the estimated strength and failure mode of the walls using the code formulations with those obtained from the numerical study indicates that in some cases (particularly the squat walls and shear-controlled walls) the codes did not predict the behaviour of the wall panels satisfactorily. This may be attributed to the multiple governing modes of failure in real cases, while the code formulations only consider a particular failure mode. The findings presented here highlight the need for updated design codes.

Impact of Openings on the In-Plane Strength of Confined and Unconfined Masonry Walls: A Sustainable Numerical Study

While openings are an essential requirement in buildings as a source of access, fresh air and sunlight, these openings cause a reduction in the lateral stiffness and torsional resistance of masonry wall units. A detailed numerical investigation was carried out to explore the impact of the opening percentage on the in-plane stiffness and lateral strength of unconfined and confined masonry wall panels prepared using calcium silicate bricks, for sustainable masonry structures. A commercially available FEM package (ANSYS) was used to carry out comparative analysis of ten wall panels, five of each type (confined and unconfined masonry walls) with concentrically located openings of varying sizes (0% to 16.5%). A simplified micro-modeling technique following the Newton Raphson Algorithm was adopted. Results revealed that the confined masonry approach unveiled a more reliable anti-seismic response along with improved in-plane strength in the case of confined masonry walls. The failure type shifted from pure flexural to more of a blend of shear and flexure after the opening percentage increased to 10.09% in unconfined masonry walls, which was not the case where confinement was provided. Based on the outcomes, it is strongly recommended to adopt confined masonry in highly seismic-prone areas to avoid catastrophic damage caused by earthquakes.

Fragility analysis of masonry wall subjected to blast loading

The present research focuses on developing the Fragility Curves (FC) of masonry panels subjected to various blast scenarios considering extensive parameters such as the effect of variation in types of masonry (unreinforced and reinforced) and blast explosion (air and surface). The Fragility Curve (FC) is a suitable way of illustrating the vulnerability of structure against blast load. Herein; fragility analysis of Solid Brick Masonry (SBM), Hollow Brick Masonry (HBM) and Reinforced Hollow Brick Masonry (RHBM) wall panels were carried out to assess their vulnerability against blast load using explicit finite element approach. The FC(s) were plotted considering uncertainties in blast parameters viz., weight of charge (W) and standoff distance (R). Two types of FC(s) were plotted: FC-1, with Probability of Failure (PF) as ordinate and W as abscissa; and FC-2, with PF on ordinate-axis and scaled distance Z [f (W, R)] on abscissa. Monte Carlo simulation (MCS) was adopted to generate random sample sets of variables based on the mean value and coefficient of variation. The failure criterion assumed in this study is based on the inelastic tension damage curve generated for the masonry in accordance with the experimental results. Also, a Damage Index was established having four levels of damage- Minor Damage (MD), Repairable Damage (RD), Non-Repairable Damage (NRD) and Total Damage (TD). In addition, limit state function was defined in terms of cracking strain for which the threshold values corresponding to each damage level was specified on the basis of tension damage curve. The various critical values of W and Z corresponding to the probability of TD being 90% were reported from the FC(s). It was found that percentage increase in demand of W critical for RHBM was about 100%–400% approximately for various standoff distances between 5 m and 40 m. Also, due to strengthening value of Z critical decreased to 21% and 27.5% respectively for surface and air blast scenario respectively.

Strengthening of Un-Reinforced Brick Masonry Walls Using Epoxy Mortar

Abstract This study is carried out to investigate the effectiveness of using externally applied epoxy mortar on joints of masonry wall panels to enhance their load carrying capacity under axial compressive and lateral loads. A total of six 113 mm thick masonry wall panels of size 1200 x 1200 mm were constructed for this study. Four out of six walls were strengthened using locally available CHEMDUR-31 epoxy mortar on joints. The remaining two walls were tested as control specimens. The control and strengthened wall panels were tested under axial compression and lateral loads. In axial compression test, out of plane central deflection and vertical strain at the center of wall panel were recorded while in lateral load test, in-plane lateral displacement of wall and horizontal strain at the center were recorded at each load increment. Failure pattern of each wall panel is also studied to notice its structural behavior. The results of this experimental study showed an increase of 45% and 60% in load carrying capacity under axial compression and lateral bending, respectively by the use of strengthening technique employed in this study.

Investigation on Lateral Loading on Masonry Walls

5) Though a traditional material used for construction for ages, masonry is a complex composite material, and its mechanical behavior is influenced by a large number of factors, is not generally well understood. This research aims to study the methodology available in the literature to evaluate the increase in performance of masonry by applying different reinforcement options under in-plane lateral loading. Nonlinear static analysis has been carried out as part of this research to achieve the above objectives. Different unreinforced masonry wall panels were analyzed at various load conditions. Material properties for the masonry wall were taken from the experimental test results of previous literature. The walls were first checked for two failure mechanisms. The stress distributions of walls were checked in each step of analysis and shear failure, and rocking failure was found. Each wall was then analyzed for six different reinforcement options. The comparison of results obtained from the reinforced wall analysis with that of the unreinforced wall indicated significant increase in lateral load-bearing capacity and decreased wall displacement with reinforcement. The maximum increase in load-bearing capacity was achieved by adding chicken wire mesh or CFRP bands throughout the wall while the maximum decrease in displacement was achieved by adding 12 mm diameter bars at the spacing of one meter.

Review of compatibility between SANS 10400 deemed-to-satisfy masonry wall provisions and loading code

South Africa has a housing shortage estimated in excess of 2 million units. This backlog is being addressed predominantly with the construction of 40 m2 low-income, single-storey, detached, state-subsidised houses built with conventional concrete masonry units, regulated by the Application of the National Building Regulations, SANS 10400. However, several developments warrant a reconsideration of SANS 10400 deemed-to-satisfy masonry wall provisions. Two critical configurations of single-storey, unreinforced, bonded masonry walls are generated, based on these deemed-to-satisfy provisions. Subsequently, a simplified micro-scale finite element model is used to analyse these configurations under serviceability and ultimate limit state loading conditions. Characterisation tests of the concrete masonry material, together with numerical fitting to test data and data taken from literature, generate the necessary parametric input. The numerical analyses reveal that in half of the load cases, the walls' resistances failed to achieve the design load as required by the South African loading code. A significant shortfall was found for the out-of-plane resistance against the wind load, as well as structural vulnerability under seismic loading due to the geometric layout permitted by the deemed-to-satisfy rules. This indicates that the SANS 10400 provisions for masonry wall panel geometries require reconsideration, especially given the recent revision of the South African loading code.

Orthotropic homogenized modeling of masonry wall panels

Orthotropic homogenized modeling of masonry wall panels

English

English

A method for predicting failure load of masonry wall panel based on structural stress state

This paper proposed a method for predicting failure loads of masonry wall panels subject to uniformly distributed lateral loading based on a concept of structural stress state. Firstly, the characteristics of the structural stress state of masonry wall panels subjected to uniform distributed lateral loading were investigated through experimental results. Then, a new parameter was proposed to characterize the structural stress state. Next, the relation of the failure loads between a specified base wall panels and other wall panel was established using the proposed parameter. In this way, a method (called a ST method) based on a structural stress state parameter to predict the failure load of masonry wall panel from the base wall panel was established. The following case studies validated the ST method by comparing the predicted failure load with the experimental results, as well as those predicted from the existing yield line theory (YLT), the FEA method and the GSED-based cellular automata (CA) method. The ST method provided an innovative way of structural analysis on the basis of structural stress state.

Strengthening of Load Bearing Masonry Wall Panels with Externally Bonded Precast Textile Reinforced Concrete Laminate

Textile Reinforced Concrete (TRC) has gained worldwide popularity as a strengthening material for masonry structures in the recent years. As of today, the application of TRC for masonry strengthening is either by cast-in-place methodology or by spraying method. The present work is a first-of-its kind study, which explores the feasibility of using externally bonded precast TRC laminate for strengthening of load bearing brick masonry wall panels. The binder used in TRC itself is used as adhesive for adhering the TRC laminate to masonry wall panels. Experimental investigations were carried out on unstrengthened and strengthened brick masonry wall panels under axial compression and combined axial compression and shear loading. The influence of TRC strengthening system is assessed by examining the performance indicators such as strength, stiffness and deformation. Based on the investigations, the use of externally bonded precast TRC laminate is found to be a feasible solution to strengthen brick masonry walls to have the required structural adequacy.