• Structural Engineering and Mechanics
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• v.50 no.1
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• pp.121-135
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• 2014

Stone masonry structures are widely used around the world, but they deteriorate easily, due to low shear strength capacity. Many techniques have been developed to increase the shear strength of stone masonry constructions. The aim of this experimental study was to investigate the performance of stone masonry walls strengthened by metal connectors as an alternative shear reinforcement technique. For this purpose, three new metal connector (clamp) types were developed. The shear strength of the walls was improved by applying these clamps to stone masonry walls. Ten stone masonry walls were structurally tested in diagonal compression. Various parameters regarding the in-plane behavior of strengthening stone masonry walls, including shear strength, failure modes, maximum drift, ductility, and shear modulus, were investigated. Experimentally obtained shear strengths were confirmed by empirical equations. The results of the study suggest that the new clamps developed for the study effectively increased the levels of shear strength and ductility of masonry constructions.

• Journal of the Earthquake Engineering Society of Korea
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• v.19 no.4
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• pp.173-181
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• 2015

In this study, material tests were performed on the masonry specimens constructed with bricks and mortar used in Korea. The specimens included two types of thickness(0.5B and 1.0B) and physical conditions (good and poor). It was shown that 1.0B specimens have 3.2~1.8 times larger shear strength than 0.5B specimens and shear strength of specimens in poor condition was 66%~38% of those in good condition. Average shear stress of masonry-infills was calculated from previous experimental studies, and relationships with failure mode, material strength of masonry, aspect ratio, and frame-to-infill strength ratio were investigated. In addition, the effects of masonry strength on the seismic performance of a masonry-infilled frame was studied using a simple example building. It can be seen that the obtained average shear stress were considerably higher than the default masonry shear strength recommended by the ASCE 41, and low values the strength of masonry does not guarantee conservative evaluation results due to the early shear failure of frame members.

• Earthquakes and Structures
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• v.25 no.3
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• pp.149-160
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• 2023

Over the course of the last 4-5 years, India's northeastern region have widely used Autoclaved Aerated Concrete (AAC) blocks to construct load-bearing masonry structures. The aim of this investigation is to examine the shear characteristics of AAC masonry triplet assemblage strengthened by using two techniques, i.e., the bead joint (BJ) and the bed-head joint (BHJ) technique. Three unique variations of wire mesh were involved in the strengthening method. Furthermore, three strengthening configurations were used to strengthen each of the three wire mesh variations and the two-strengthening method, i.e. (-), L and (Z) configuration. The unreinforced and reinforced triplet masonry wallets were tested under direct shear test. From the results obtained, the 'BJ'triplet masonry wallets observed an enhanced in shear strength of about 2.23% to 23.33 % whereas the 'BHJ' triplet masonry wallets observed an enhanced in shear strength of about 22.92% to 50.69%. The "BHJ" strengthening method effectively enhance the shear strength of the triplet masonry wallets compared to the "BJ" and the "UR" wallets with an increase in capacity as the wire mesh strength increases. Furthermore, in terms of the strengthening configuration, the (Z) configuration performs better, followed by the (L) and (-) configuration demonstrating the strengthening configuration effectiveness.

• Computers and Concrete
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• v.33 no.5
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• pp.519-533
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• 2024

Many materials including cementitious concrete-type materials undergo material property changes during high-rate loading. There is a wealth of research regarding this phenomenon for concrete in compression and tension. However, there is minimal knowledge about how mortar material used in concrete masonry unit (CMU) construction behaves in high-rate shear loading. A series of experiments was conducted to examine the bond strength of mortar bonded to CMU units under high-rate shear loading. A novel experimental setup using a shock tube and dynamic ram were used to load specially constructed shear triplets in a double lap shear configuration with no pre-compression. The Finite Element Method was leveraged in conjunction with data from the experimental investigation to establish if the shear bond between concrete masonry units and mortar exhibits any rate dependency. An increase in shear bond strength was observed when loaded at a high strain rate. This data indicates that the CMU-mortar bond exhibits a rate dependent strength change and illustrates the need for further study of the CMU-mortar interface characteristics at high strain rates.

• Earthquakes and Structures
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• v.26 no.5
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• pp.363-382
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• 2024

In India's north-eastern region, low-strength autoclaved aerated concrete (AAC) blocks are widely used for constructing masonry structures, making them susceptible to lateral forces due to their low tensile and shear strengths and brittleness nature. The absence of earthquake-resistant attributes further compromises their resilience during seismic events. An economically viable solution to enhance the structural integrity of these masonry structures involves integrating steel wire mesh within the masonry mortar joints. This study investigates the in-plane shear behaviour of AAC masonry by employing two approaches: incorporating steel wire mesh within the masonry bed joint "BJ" and the masonry bed and head joint "BHJ". These approaches aim to augment strength and ductility, potentially serving as earthquake-resistant attributes in masonry structures. Three distinct variations of steel wire mesh and three reinforcing arrangements, i.e. (-), (L) and (Z) arrangement were employed to reinforce the two approaches. The test result reveals a significant enhancement in structural performance upon inclusion of steel wire mesh in both reinforcing approaches, with the "BHJ" approach outperforming the "BJ" approach and the unreinforced masonry, along with increase in capacity as the wire mesh size increases. Furthermore, the effectiveness of the reinforcing arrangement is ranked with the (Z) arrangement showing the largest performance, followed by the (L) and (-) arrangement.

• Earthquakes and Structures
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• v.22 no.4
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• pp.355-372
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• 2022

The study is part of an experimental program on full-scale Un-Reinforced Masonry (URM) wall panels strengthened with Textile reinforced mortars (TRM). Eight brick walls (two with and five without central opening), were tested under the diagonal tension (shear) test method in order to investigate the strengthening system effectiveness on the in-plane behaviour of the walls. All the URM panels consist of the innovative components, named "Orthoblock K300 bricks" with vertical holes and a thin layer mortar. Both of them have great capacity and easy application and can be constructed much more rapidly than the traditional bricks and mortars, increasing productivity, as well as the compressive strength of the masonry walls. Several parameters pertaining to the in-plane shear behaviour of the retrofitted panels were investigated, including shear capacity, failure modes, the number of layers of the external TRM jacket, and the existence of the central opening of the wall. For both the control and retrofitted panels, the experimental shear capacity and failure mode were compared with the predictions of existing prediction models (ACI 2013, TA 2000, Triantafillou 1998, Triantafillou 2016, CNR 2018, CNR 2013, Eurocode 6, Eurocode 8, Thomoglou et al. 2020). The experimental work allowed an evaluation of the shear performance in the case of the bidirectional textile (TRM) system applied on the URM walls. The results have shown that some analytical models present a better accuracy in predicting the shear resistance of all the strengthened masonry walls with TRM systems which can be used in design guidelines for reliable predictions.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.89-92
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• 2008

This study investigates the shear behavior of architectural masonry veneer wall reinforced with specific reinforcement details proposed by this study. For this purpose, experimental tests were conducted using one un-reinforced masonry(URM) wall specimen and three reinforced masonry(RM) wall specimens under quasi static cyclic loads. Un-reinforced(plain) masonry wall is expressed that behavior and failure mode are different for aspect ratio(L/H) and axial compressive force. The test variables are wall aspect ratio and presence of reinforcement. These specimens are masonry structure for architectural clading that is not to exist the axial compressive force. thus the axial compressive force is excepted from test variable. Test result, Behavior of specimens are dominated over rocking mode, but final failure modes are combined with different behaviors. And FEMA273 has proposed the equation of shear strength of masonry pier subjected to in-plane loading. Shear strength equations are classified four types of failure mode that is Rocking, and Toe-Crushing, Bed-Joint-Sliding and Diagonal-Tension. FEMA273 equations predict the behavior modes well, but shear strength is shown in different result.

• Earthquakes and Structures
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• v.25 no.3
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• pp.177-186
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• 2023

Reinforced concrete frames with a masonry infill panel is a structural typology frequently used worldwide. In seismic cases, the interaction between the masonry infill and the RC frames constitutes one of the most complex subjects in earthquake engineering. In this work, an enhancement of an existing numerical model is proposed to improve the estimation of lateral strength and stiffness of masonry-infilled frame structures and predict their probable failure modes. The proposed improvement is based on attributing corrective coefficients to the shear strength of each diagonal shear spring of the macro element, which simulates the masonry infill. The improved numerical model is validated by comparing the results with those of the original numerical model and with experimental results available in the literature. The enhanced macro element model can be used as a powerful, accessible tool for assessing the capacity and stiffness of masonry-infilled frame structures and predicting their probable failure modes.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.9
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• pp.4216-4222
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• 2011

In this study the inelastic behavior of the existing school buildings with infilled masonry walls is analysed by pushover method. The shear stiffness and strength of masonry wall is calculated from the prior experimets and verified by inelastic analysis. The height of infilled masonry wall affects the structural behavior. The higher the masonry wall height, the higher the initial shear stiffness and strength of masonry wall. As the cracks are developed, the strength of masonry wall is much decreased. The proposed inelastic analysis method shows similar results with the experiments and can be used as inelastic analysis model of reinforced concrete buildings with infilled masonry walls.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.35 no.9
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• pp.191-198
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• 2019

All over the Republic of Korea, there are many masonry buildings which have been built since 1970s. When the earthquake at Po-Hang occurred, this is the main cause of huge damage because the masonry buildings have not seismic capacity. When masonry buildings are failed, two type of the failure modes can be shown, which are in-plane mode and out-plane mode. In-plane mode can have seismic capacity in masonry so diagonal shear test is performed in this study. The purpose of this study was to find the best way to reinforce the materials through the diagonal shear test. Through the test, shear stress and shear modulus of elasticity will be calculated, referred to the ASTM E 519-02. The variables in this test are ${\phi}3$ wire, three types of wire meshes, polypropylene strap and different types of brick. Each variable is applied to the same condition of the $1.2m{\times}1.2m$ masonry walls which are made by ASTM E 519-02. Compared to each variable with shear stress and shear modulus of elasticity, the best way of reinforcing method to have seismic capacity will be proved in this study.