In-plane Shear Behavior Research Articles

Temperature and rate dependent shear characterization and modeling of spread-tow woven Flax/PP composite laminates

This paper investigates the in-plane shear behavior of spread-tow woven structured flax fiber-reinforced polypropylene composites, focusing on temperature and displacement rate effects. For this aim, the study includes bias-extension experiments to characterize the shear behavior of the material. Several experiments were conducted at different displacement rates and temperature levels. The temperature levels were chosen to encompass the material's behavior during solid and molten-state thermoforming, given the melting and decomposition temperatures acquired from differential scanning calorimetry and thermogravimetric analysis tests, respectively. A new fixture was designed and manufactured to allow pre-heating of the oven and rapid placement of the samples, which in turn, prevents their degradation for the time duration required to reach a uniform temperature distribution in the oven. During the experiments, the 3D digital image correlation technique accurately measured local deformations and strains on the specimen's surface under varying conditions. Further, a finite element model is developed, incorporating a fiber reorientation algorithm with a hypo-elastic shear model to simulate the material's temperature and rate-dependent behavior. The finite element shear angle distributions, as well as the shear angle-force and shear angle-displacement curves, are compared with the Digital Image Correlation (DIC) data and load measurements for different test conditions, showing good agreement between the numerical and experimental approaches.

Comparative Studies on In-Plane Shear Behavior of Masonry Wallettes Retrofitted with Mortar, UHPC, and ECC Ferrocement: Shotcrete and Prefabricated Panels

Masonry walls, prevalent in many historical and contemporary structures, often require retrofitting to meet modern safety and performance standards. Motivated by the need for efficient and reliable retrofitting solutions, this research investigates the potential of various types of ferrocement, reinforced with high-strength steel meshes, to enhance the in-plane shear behavior of brick masonry walls. Through rigorous diagonal compression tests on nine masonry wallettes, the study evaluated the performance of ferrocement overlays in terms of overlay configuration (asymmetric or symmetric), cementitious material type (mortar, ECC, or UHPC), the presence or absence of steel mesh, and construction method (shotcrete or prefabricated panels). The results indicated that UHPC and ECC overlays significantly enhanced post-cracking deformation capacity. Compared to the asymmetric retrofit, the symmetric retrofit led to more uniform deformation in the retrofitted wallette, effectively improving the maximum shear by up to 119 %. While UHPC shotcrete was more effective in improving the shear strength, ECC shotcrete led to the highest rupture shear strain and pseudo-ductility for the retrofitted wallette, reaching 0.83 % and 17.2, respectively. Moreover, although steel mesh inclusion in the ferrocement overlay was crucial in enhancing post-peak ductility, its impact on shear strength of the retrofitted wallettes was minimal. The test results also demonstrated that the developed prefabricated UHPC panels emerged as an effective retrofitting solution to simultaneously improve the strength, deformation capacity, and ductility for masonry wallettes. In addition to the experimental investigation, a new strength model, accounting for various key design variables, was developed, offering reliable shear strength predictions for the retrofitted wallettes.

Experimental and Numerical Characterization of the In-Plane Shear Behavior of a Load-Bearing Hollow Clay Brick Masonry System with High Thermal Performance

Modern masonry systems are generally built with hollow clay bricks with high thermal insulating properties, fulfilling the latest sustainability and environmental criteria for constructions. Despite the growing use of sustainable masonries in seismic-prone countries, there is a notable lack of experimental and numerical data on their structural behavior under lateral in-plane loads. The present study investigates the in-plane shear behavior of load-bearing masonry walls with thin bed joints and thermal insulating hollow clay blocks. Shear-compression tests were performed on three specimens to obtain information about their shear strength, displacement capacity and failure modes. The experimental characterization was supplemented by three shear tests on triplets, along with flexural and compression tests on the mortar for the thin joints. Furthermore, two Finite Element (FE) models were built to simulate the shear-compression tests, considering different constitutive laws and brick-to-brick contact types. The numerical simulations were able to describe both the shear failure modes and the shear strength values. The results showed that the experimental shear strength was 53% higher than the one obtained through Eurocode 6. The maximum shear load was found to be up to 75% greater compared to similar masonry specimens from the literature. These findings contribute to a better understanding of the potential structural applications of sustainable hollow clay block masonry in earthquake-prone areas.

Temperature- and rate-dependent tensile behaviour of unidirectional carbon/polyamide-6 composite under off-axis loading with oblique tabs

Unidirectional carbon/polyamide-6 (CPA6) is a thermoplastic composite with attractive properties for many industrial applications. However, shortage of experimental data may hinder the development of reliable material models. This paper is the first to provide a complete dataset for the tensile behaviour of unidirectional CPA6, including the longitudinal, transverse, in-plane shear, and off-axis response, at different temperatures and (quasi-static) strain rates. The oblique end tab design, already proven in the literature for off-axis testing of composites at room temperature, was successfully extended to the elevated temperature of 120 °C. The use of cardboard tabs and fast-curing adhesive greatly simplified the tab manufacturing and application for all the combinations of fibre angles, temperatures and strain rates. Digital image correlation (DIC) was performed through the window of the temperature chamber to verify the homogeneous strain field produced by the oblique tabs. The in-plane shear behaviour was extracted from the off-axis tests, allowing to estimate the shear modulus and shear strength. Finally, the robustness of the experimental results generated in this study was demonstrated with well-established analytical models that could excellently predict the elastic modulus, Poisson's ratio, and failure stress at different fibre angles.

Determination of the In-Plane Shear Behavior of and Process Influence on Uncured Unidirectional CF/Epoxy Prepreg Using Digital Image Correlation Analysis

The investigation of the in-plane shear behavior of prepreg is crucial for understanding the generation of wrinkles of preforms in advanced composite manufacturing processes, such as automated fiber placement and thermoforming. Despite this significance, there is currently no standardized test method for characterizing uncured unidirectional (UD) prepreg. This paper introduces a ±45° off-axis tensile test designed to assess the in-plane shear behavior of UD carbon fiber-reinforced epoxy prepreg (CF/epoxy). Digital image correlation (DIC) was employed to quantitatively track the strains in three dimensions and the shear angle evolution during the stretching process. The influences of the temperature and stretching rate on the in-plane shear behavior of the prepreg were further investigated. The results reveal that four shear characteristic zones and wrinkling behaviors are clearly distinguished. The actual in-plane shear angle is significantly lower than the theoretical value due to fiber constraints from both the in-plane and out-of-plane aspects. When the off-axis tensile displacement (d) is less than 15.6 mm, the ±45° specimens primarily exhibit macroscale in-plane shear behavior, induced by interlaminar interface shear between the +45° ply and −45° ply at the mesoscale. The shear angle increases linearly with the d. However, when d > 15.6 mm, fiber squeezing and wrinkling begin to occur. When d > 29 mm, the in-plane shear disappears in the completely sheared zone (A). The reduction in the resin viscosity of the CF/epoxy prepreg caused by increased temperature is identified as the primary factor in lowering the in-plane shear force resistance, followed by the effect of the increasing resin curing degree. Higher shear rates can lead to a substantial increase in shear forces, eventually causing cracking failure in the prepreg. The findings demonstrate the feasibility of the test method for predicting and extracting uncured prepreg in-plane shear behaviors and the strain-rate and temperature dependency of the material response.

Numerically assisted calibration procedure of nonlinear in-plane shear properties of unidirectional composite laminae based on off-axis tensile experiments

In this paper, a novel methodology is presented to evaluate the true nonlinear shear response of continuous fiber-reinforced plastic (CFRP) unidirectional laminae. It requires simple off-axis tensile experiments to be conducted and a finite element (FE) representation of them with a material constitutive law capable of handling nonlinearity in shear. Upon successful evaluation of the normal stiffness properties, the shear stress-strain response is derived via numerical calibration of the underlying FE models. The presented approach is also demonstrated by processing the raw data of an extensive material characterization test campaign conducted on a thermoplastic matrix CFRP. The outcome is compared to the conventional methods for shear response derivation using relevant standards such as ASTM D3518 and ASTM D5379. It has been successfully demonstrated that the pseudo-hardening phenomenon obtained from standard shear experiments as a result of fibers aligning with load direction can be eliminated with off-axis specimen tension experiments, thus, the true shear stress versus deformation response can be extracted up to failure. The main purpose of current work is to demonstrate the inconsistency in the available standard methods related to mechanical testing-based derivation of nonlinear in-plane shear behavior of UD plies. In addition, a novel technique is presented to achieve a more accurate prediction of nonlinear shear stress and strain along the entire representative loading range that contributes to more accurate simulations of composite parts up to failure and thus, better strength predictions.

Dependence of a Steel-concrete-Steel Sandwich Structure Behavior under Pure In-Plane Shear Loading on the Reinforcement Ratio

This paper deals with failure modes of a steel-concrete-steel sandwich loaded by pure in-plane shear. Current research together with the developed models imply that increase of reinforcement ratio leads to decrease of ductility and possibly to change a failure mode from yielding of steel in tension to crushing of concrete in compression which results in brittle failure. In order to give a reader basic information about in-plane shear behavior of a steel-concrete-steel sandwich, an analytical model is introduced. Japanese experimental program that researched a behavior of SCS panels with reinforcement ratio 2.3%, 3.2% and 4.5% is also shown. In addition to the effect of changing the reinforcement ratio, the experimental program also investigated the effect of the transverse steel plate on the ductility of test panels with a degree of reinforcement of 3.2%. The next chapter describes the methodology used by the author to model the individual parts of the model, the loads, and especially the method of supporting the model. This is followed by the presentation of the results of the analysis on the calibration and extrapolation models. Finally, a discussion is conducted on the agreement of the analysis results on the calibration models with the Japanese experimental results, followed by an evaluation of the analysis results on the extrapolation models. According to the results on the extrapolation models the critical degree of reinforcement at which a change in the failure mode of the structure occurs under in-plane shear loading is around 13%.

In-plane Shear Behaviour of Novel Thick Stitched Textile Reinforcements Part II: Quantitative Analysis of Shear Locking Angle

A quantitative analysis of the in-plane shear test results reported in PhD thesis of Hafeth Bu Jldain was preformed in this paper. Analysis of the results was conducted from experimental and analytical bases. It was conducted experimentally through comparing the results obtained for uO-APT samples with the results obtained for samples made from an industrial fabric manufactured by GmbH Saertex. The analytical validation was conducted through systematic Taguchi plans. These plans investigate, the effect of the type of reinforcement (A and B), the effect of the number of layers, and the effect of stitching setup (R-45, R+45, R0 and R90) on the behavior of the reinforcements. The plans primarily analyzed the extent to which the reinforcement may shear and the force required to do so.Shear test results for stitching orientation R-45 and R+45 show the ability of the new fabric to shear under lower shear forces, which ranged between 0 N and 25 N needed to shear uO-APT reinforcements to shear angles ranging from 50° to 55° before wrinkling was observed.

The diagonal shear behavior of masonry walls fabricated with historical lime-based mortar and retrofitted with near surface mounted method

The historical monuments in different regions of the world were constructed using local materials. Sarooj was a lime-based mortar utilized extensively in the construction of Unreinforced Masonry (URM) buildings in some Middle Eastern countries in the past centuries. However, few studies have been conducted on the mechanical properties of masonry fabricated with Sarooj and strengthening of the elements in which this type of mortar was used. In the present study, the in-plane shear behavior of URM wallettes fabricated with Sarooj mortar and retrofitted with Near Surface Mounted (NSM) Glass Fiber Reinforced Polymer (GFRP) bars is investigated through an experimental and numerical study. In this regard, first, diagonal shear tests are conducted on square wallettes. The test specimens include bare and retrofitted wallettes. The type of paste used for filling the grooves in the NSM method and the retrofitted face of the wallettes are the main variables whose effects are investigated in the experimental program. In addition to the NSM method, the in-plane behavior of walls retrofitted with a novel technique named Epoxy Filled Joint (EFJ) is investigated in the experimental phase of the present study. Then, through a numerical study, the wallettes retrofitted with the NSM method are simulated in Finite Element (FE) software Abaqus following a macro-modeling approach. The results of the experimental study confirmed that the strengthening of the URM wallettes with the NSM method not only enhanced their ultimate in-plane shear strength, but also improved the ultimate drift capacity of the wallettes. Furthermore, the shear stress-drift curves obtained from the FE model were in good agreement with those obtained from the tests. In addition, the test results showed that the EFJ method significantly increased the in-plane shear strength of the wallettes.

A Study on Damage of T800 Carbon Fiber/Epoxy Composites under In-Plane Shear Using Acoustic Emission and Digital Image Correlation.

In addition to measuring the strain, stress, and Young's modulus of materials through tension and compression, in-plane shear modulus measurement is also an important part of parameter testing of composites. Tensile testing of ±45° composite laminates is an economical and effective method for measuring in-plane shear strength. In this paper, the in-plane shear modulus of T800 carbon fiber/epoxy composites were measured through tensile tests of ±45° composite laminates, and acoustic emission (AE) was used to characterize the damage of laminates under in-plane shear loading. Factor analysis (FA) on acoustic emission parameters was performed and the reconstructed factor scores were clustered to obtain three damage patterns. Finally, the development and evolution of the three damage patterns were characterized based on the cumulative hits of acoustic emission. The maximum bearing capacity of the laminated plate is about 17.54 kN, and the average in-plane shear modulus is 5.42 GPa. The damage modes of laminates under in-plane shear behavior were divided into three types: matrix cracking, delamination and fiber/matrix interface debonding, and fiber fracture. The characteristic parameter analysis of AE showed that the damage energy under in-plane shear is relatively low, mostly below 2000 mV × ms, and the frequency is dispersed between 150-350 kHz.

On strain rate effect and high-velocity impact behavior of carbon fiber reinforced laminated composites

In this paper, the tensile and in-plane shear behaviors of carbon fiber reinforced laminated composites (CFRLCs) under high strain rate loading were experimentally investigated. The strain and damage processes of the specimens were obtained using the Digital Image Correlation (DIC) method and a high-velocity camera. Quasi-static test results were used as the control group for obtaining the dynamic correction factors of the material system under high strain rate conditions. In addition, high-velocity impact (HVI) tests with different impact velocities and angles were conducted on CFRLCs. The dynamic correction factors were used in HVI simulations to consider the effect of strain rate. The energy absorption mechanisms and failure modes of laminates under different impact conditions were analyzed using testing and simulated results. It is found that during the HVI, matrix tension and fiber tension failures are the main failure modes. The energy absorbed by the laminate in oblique impact is larger than the one in normal impact. The possible reason is that the increase rate of the damage area with the four failure modes in oblique impact is larger than the one in normal impact.

In-plane shear behaviour of concrete sandwich panels reinforced with various geogrids

Seismic occurrences have caused severe damage and even the collapse of fragile unreinforced masonry structures. New technologies are replacing these conventional methods of construction; concrete sandwich panels (CSP) are one such technique gaining popularity. In-plane diagonal shear strength of concrete sandwich panels is studied experimentally, and the effect of incorporating geogrids on the deformation capability and load-bearing capacity is reported. Two forms of geogrid material, plastic uniaxial geogrid (PUG) and polyester biaxial geogrids (PBG2 and PBG3) are used to improve the strength and ductility of concrete sandwich panels. Diagonal compression tests have been carried out better to understand the behavior of CSP under in-plane strength. This paper also discusses the effect of the different mixes, the effect of geogrids, load-deformation behaviour, shear capacity, deflection ductility factor, mode of failure, shear strength, and energy dissipation. In contrast to the control specimen, specimens cast with plastic geogrid had a 13.7% and 26% improvement in shear capacity and load-bearing capability for the two types of micro-concrete mixes used in this study. The conclusion reached is that plastic uniaxial geogrid is effective in improving the concrete sandwich panels’ load-bearing capacity, shear capacity, and deformation ability. Polyester biaxial geogrids enhanced the ductility of the concrete sandwich panels.

Ultimate in-plane shear behaviour of clay brick masonry elements strengthened with TRM overlays

This paper studies the response of unreinforced masonry (URM) members made of hydraulic lime mortar and fired clay bricks, commonly found in heritage structures, strengthened with textile reinforced mortar (TRM) overlays. The investigation includes URM and TRM-strengthened diagonal compression tests on square panels, and relatively large-scale wall specimens subjected to combined gravity and lateral cyclic loads. Complementary compression, tension, and interface material tests are also carried out. The diagonal panel tests show that the TRM effectiveness depends in a non-proportional manner on the overlays, render thickness, and substrate strength. The enhancement in stiffness, strength, and ultimate shear strain, using one to four mesh layers on each side, is shown to vary in the range of 49–132%, 102–536%, and 300–556% respectively. It is shown that strut crushing typically governs the response of such low-strength URM masonry elements confined by TRM overlays. The cyclic tests on the comparatively larger walls show that the TRM is effective, shifting the response from URM diagonal tension to rocking, and enhancing the stiffness, strength, and ultimate drift capacity by more than 160%, 30%, and 130%, respectively. It is shown that analytical assessment methods for predicting the response of TRM-strengthened and URM members in terms of stiffness, strength and load-deformation can be reliably adapted. The cumulative contribution of the URM and TRM components, in conjunction with a suitable fibre textile strain, is also found to offer an improved prediction of the shear strength compared to codified procedures. The findings enable the evaluation and improvement of analytical models for determining the main inelastic response parameters of TRM-strengthened masonry and provide information for validating future detailed nonlinear numerical simulations.

Experimental and numerical insights on the in-plane behaviour of unreinforced and TRM/SRG retrofitted brick masonry walls by diagonal compression and shear-compression testing

The experimental determination of the parameters that characterise the in-plane shear behaviour of masonry structures is still a challenging task. Different authors have identified the key role of tensile strength in the definition of the in-plane shear behaviour of masonry, but unfortunately its direct experimental characterisation is not always feasible, and masonry’s tensile strength needs to be obtained from complex testing methodologies. As a result, tensile strength needs to be assessed from testing setups such as diagonal compression testing and shear compression testing when the failure mode of masonry is featured by tensile diagonal cracking. However, different formulations are available in the scientific literature regarding the interpretation of the experimental results derived from such tests. This work provides new insights on the interpretation of in-plane shear experimental behaviour of double-leaf historical clay brick masonry walls with low strength mortar joints, both unreinforced and retrofitted with textile reinforced mortar and steel reinforced grout. The research evaluates results derived from both testing methodologies, and investigates the potential correlation between them to fully characterise the in-plane shear behaviour of masonry walls. Finally, a numerical model is used to simulate each testing configuration and study the stress state at the centre of the walls to determine the tensile strength and its correlation with the shear strength and the maximum load attained.

In-plane shear behavior of brick masonry walls strengthened with basalt textile-reinforced concrete

The in-plane shear behavior of the brick masonry walls strengthened with basalt textile-reinforced concrete (BTRC) was mainly investigated. Diagonal shear tests with different strengthening methods and textile layers were performed. Research results show that the BTRC transforms brittle failure of the brick walls into ductile failure, the BTRC and brick wall work well together. Double-sided strengthening is more effective in reinforcing the shear capacity of the masonry walls. The strengthening effect improves with textile layers, especially for double-sided strengthening. Furthermore, the shear strength values calculated by current standard are lower than tests.

Test and analysis on in-plane shear behavior of precast concrete hollow core slabs

Precast concrete hollow core (PHC) slabs are mostly used in industrial and civil buildings because of the low weight and high efficiency of construction. The previous researches are mainly focused on the out-of-plane bending and shear behavior of PHC slabs. However, the in-plane shear behavior of the PHC slabs with high-strength tendons is not fully understood yet. In this regard, to investigate the in-plane shear behavior of PHC slabs, shear tests were conducted on a new long PHC slab with high-strength tendons and a new spliced slab in the present paper. The spliced slab was composed of two PHC short slabs with U-type bars, post-pouring concrete and anchorage bars. Subsequently, finite element models were established and validated by the test. Parametric analysis was conducted on the spliced slab to study the effect of the reinforcement ratio of tendons, concrete strength, tendon prestress, position of loading point, etc. Furthermore, based on the deep beam theory of single generalized displacement, the modified theoretical formulas on the in-plane initial stiffness of the specimens were illustrated. The results show that the mechanical behavior of the spliced slab was better than that of the long slab, including shear capacity, energy dissipation capacity and ductility. The initial stiffness and shear capacity of the spliced slab improved obviously with the reduction of the distance between the supports. The difference between in-plane initial stiffness of the PHC slab obtained from the modified theoretical formulas and that obtained from experiment are within 5%, which means the proposed formula can predict the in-plane initial stiffness of the PHC slabs well. This may provide a reference for the application of the long PHC and spliced slabs in engineering.

Characterising the shear resistance of a unidirectional non-crimp glass fabric using modified picture frame and uniaxial bias extension test methods

The forming behaviour of a unidirectional non-crimp fabric (UD-NCF) consisting of polyamide stitches with a tricot-chain stitching pattern is explored. Notably, there are no stabilising tows orientated transverse to the main tow direction in this fabric, a common feature in many ‘quasi’ UD-NCFs, this allows extension of the stitch in the transverse direction under certain loading conditions. The lack of stabilising tows introduces a possible low-energy deformation mode to the UD-NCF, which is absent in biaxial fabrics and to a large extent in ‘quasi’ UD-NCFs. The in-plane shear behaviour is initially investigated using both standard ‘tightly-clamped’ picture frame tests and uniaxial bias extension tests. Preliminary results show a dramatic difference in results produced by the two test methods. During the picture frame test, fibres can be subjected to unintended tension due to sample misalignment in the picture frame rig. To mitigate error arising from this effect, the picture frame test procedure is modified in two different ways: by using an intentional pre-displacement of the picture frame rig, and by changing the clamping condition of test specimen. Results show that the modified picture frame test data contain less error than the standard ‘tightly-clamped’ test but also that the shear stiffness of the UD-NCF is notably lower when measured in the bias extension test compared to the picture frame test, mainly due to the difference in loading conditions imposed during the two tests.

In-plane shear stiffness of diversified hexagonal honeycombs: A simple energy-based approach

The conventional hexagonal honeycomb is widely used in various practical applications. The re-entrant and semi re-entrant hexagonal forms derived from the conventional one have gained large attention in recent years due to their unusual Poisson's ratio and superior mechanical performance. However, the in-plane shear behavior of the semi re-entrant hexagonal honeycomb has not been reported yet. Especially, a comparative study on the shear stiffness of the three hexagonal honeycombs is lacking. A simple energy-based approach was used in this paper to establish theoretical models for predicting the in-plane shear modulus of the hexagonal honeycombs, which were later verified by the numerical simulations. Good agreement between the theoretical and numerical results is observed. The effect of the geometrical parameters on the shear modulus and the specific shear modulus were further discussed. It is found that the conventional hexagonal honeycomb displays higher shear modulus and specific shear modulus than both the re-entrant and semi re-entrant ones, while the re-entrant hexagonal honeycomb demonstrates the lowest values of shear modulus and specific shear modulus.

In-Plane Shear Behavior of Unreinforced Masonry Wall Strengthened with Bamboo Fiber Textile-Reinforced Geopolymer Mortar

Old structures that are made of adobe or brick walls are usually unreinforced and not designed for lateral forces. In-plane loads applied to unreinforced masonry walls (URM) are the usual cause of damage and failure of old buildings. In this research, small unreinforced brick masonry wallettes, 350 mm × 350 mm and 50 mm in thickness, are strengthened using bamboo fiber textile and plastered to the face of the walls using short bamboo fiber-reinforced geopolymer mortar. The wallettes are subjected to diagonal shear tests as described by ASTM E519 to investigate the in-plane shear performance of the strengthening method. The performances of 5 wallettes strengthened on one-side with mortar only, 5 wallettes on both-sides with mortar only, 5 wallettes with textile plastered on one-side only, and another 5 wallettes with textile plastered on both-sides, are compared to 5 control specimens without any strengthening. It is observed that the wallettes strengthened on one side and both sides with textile yield an increase in shear of about 24% and 35% in average, respectively. Failure modes show that the usual failure for URM is running bond failure and for strengthened URM is columnar failure. The implications of the results can be used in developing textile-reinforced geopolymer mortar systems to strengthen URM walls.

In-plane shear strengthening of traditional unreinforced masonry walls with near surface mounted GFRP bars

In this study, the effectiveness of Near Surface Mounted (NSM) method, for in-plane shear strengthening of traditional and historical Unreinforced Masonry (URM) walls, is investigated through a comprehensive experimental study. For this purpose, square solid clay brick masonry wallettes (42 samples) with three different types of traditional mortars including gypsum mortar, lime-cement-sand mortar and lime-sand mortar are prepared and retrofitted with NSM Glass Fiber Reinforced Polymer (GFRP) bars. Then, diagonal shear tests are conducted to evaluate the in-plane shear behavior of the masonry wallettes. The effects of some key variables such as wall thickness, the retrofitted face of the wall, reinforcement ratio, and the type of paste for mounting the reinforcing bars, on the effectiveness of the retrofitting method are investigated. The results of the tests are presented in terms of the failure modes and the lateral shear stress-drift curves of the test specimens. Accordingly, the retrofitting method can enhance the in-plane shear strength, and the ultimate lateral drift capacity of the URM wallettes. According to the test results, the type of filler paste and reinforcement ratio influence the strength enhancement of the test specimens. Furthermore, in specimens retrofitted with the one-side retrofitting scheme, due to the asymmetry of walls under in-plane loads, an unexpected out-of-plane deformation is induced in the walls under in-plane load which adversely affects its global behavior.