scholarly journals Cyclic Behavior of Masonry Shear Walls Retrofitted with Engineered Cementitious Composite and Pseudoelastic Shape Memory Alloy

Sensors ◽  
2022 ◽  
Vol 22 (2) ◽  
pp. 511
Author(s):  
Alireza Tabrizikahou ◽  
Mieczysław Kuczma ◽  
Magdalena Łasecka-Plura ◽  
Ehsan Noroozinejad Noroozinejad Farsangi
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Shear Walls ◽  
Absorption Capacity ◽  
Cyclic Behavior ◽  
Masonry Walls ◽  
Cementitious Composite ◽  
Energy Absorption Capacity ◽  
Engineered Cementitious Composite ◽  
Mesh Density

The behavior of masonry shear walls reinforced with pseudoelastic Ni–Ti shape memory alloy (SMA) strips and engineered cementitious composite (ECC) sheets is the main focus of this paper. The walls were subjected to quasi-static cyclic in-plane loads and evaluated by using Abaqus. Eight cases of strengthening of masonry walls were investigated. Three masonry walls were strengthened with different thicknesses of ECC sheets using epoxy as adhesion, three walls were reinforced with different thicknesses of Ni–Ti strips in a cross form bonded to both the surfaces of the wall, and one was utilized as a reference wall without any reinforcing element. The final concept was a hybrid of strengthening methods in which the Ni–Ti strips were embedded in ECC sheets. The effect of mesh density on analytical outcomes is also discussed. A parameterized analysis was conducted to examine the influence of various variables such as the thickness of the Ni–Ti strips and that of ECC sheets. The results show that using the ECC sheet in combination with pseudoelastic Ni–Ti SMA strips enhances the energy absorption capacity and stiffness of masonry walls, demonstrating its efficacy as a reinforcing method.

scholarly journals Experimental and Numerical Study of Engineered Cementitious Composite with Strain Recovery under Impact Loading

2019 ◽  
Vol 9 (5) ◽  
pp. 994 ◽  
Author(s):  
Moncef Nehdi ◽  
Mohamed Ali
Keyword(s):  
Shape Memory ◽  
Impact Loading ◽  
Numerical Study ◽  
Absorption Capacity ◽  
Strain Recovery ◽  
Impact Behavior ◽  
Experimental Investigations ◽  
Heating Process ◽  
Cementitious Composite ◽  
Engineered Cementitious Composite

An engineered cementitious composite, endowed with strain recovery and incorporating hybrid shape memory alloy (SMA) and polyvinyl alcohol (PVA) short fibers, was subjected to drop weight impact loading. Numerical simulation of the composite’s impact behavior was performed, and the model predictions agreed well with the experimental findings. Numerical and experimental investigations demonstrated that incorporating SMA fibers in the composite yielded superior impact resistance compared to that of control mono-PVA specimens. Heat treatment stimulated the SMA fibers to apply local prestress on the composite’s matrix owing to the shape memory effect, thus enhancing energy absorption capacity, despite the damage incurred by PVA fibers during the heating process. The superior impact performance of the hybrid composite makes it a strong contender for the construction of protective structures, with a potential to enhance the safety of critical infrastructure assets against impact and blast loading.

Improving cushioning properties of a 3D weft knitted spacer fabric in a novel design with NiTi monofilaments

2018 ◽  
Vol 49 (10) ◽  
pp. 1389-1410 ◽  
Author(s):  
Mohsen Hamedi ◽  
Parisa Salimi ◽  
Nima Jamshidi
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Mechanical Stress ◽  
Energy Absorption ◽  
Absorption Capacity ◽  
Daily Activities ◽  
Energy Absorption Capacity ◽  
Static Compression ◽  
Spacer Fabric ◽  
Novel Design

Cushioning pads alleviate the effects of mechanical stress on the human body due to impacts and daily activities. One relevant application for such pads is orthopedic insoles used for diabetic foot to improve energy absorption and reduce stress gradient by using suitable materials and structures. This article considers a novel design that improves the energy absorption capabilities of cushioning pads. Experiments were conducted to evaluate the properties of the designed weft knitted spacer fabrics. Six groups of samples were knitted in which steel, polyamide, and shape memory alloy materials were utilized as spacer monofilament. Stress–strain, energy absorption and efficiency diagrams were obtained following the quasi-static compression tests carried out on the samples. Three investigation groups were adopted to evaluate the effect of the spacer monofilament material, diameter, and slope on energy absorption capacity. It was determined that shape memory alloy monofilament with 0.1 mm diameter was the optimum configuration to be utilized as spacer yarn in a typical 3D weft knitted fabric. It was also concluded that higher-inclined spacer monofilament in spacer fabric was the optimum choice for knitting cushioning pads as it absorbed more energy. The energy absorption capacity of the optimum design of spacer fabric obtained in this study, increased by a factor of 2.4 compared with commercial polyamide pads. This design can be utilized in any cushioning pad exposed to high mechanical stress due to impact, sports and daily activities.

Evaluation of reinforced concrete and reinforced engineered cementitious composite (ECC) members and structures using small-scale testing

2015 ◽  
Vol 42 (3) ◽  
pp. 164-177 ◽  
Author(s):  
Bora Gencturk ◽  
Farshid Hosseini
Keyword(s):  
Reinforced Concrete ◽  
Energy Absorption ◽  
High Energy ◽  
Absorption Capacity ◽  
System Level ◽  
Experimental Program ◽  
Small Scale ◽  
Cementitious Composite ◽  
Energy Absorption Capacity ◽  
Engineered Cementitious Composite

The behavior of reinforced concrete (RC) and reinforced engineered cementitious composites (ECC) was comparatively investigated at the component and system levels through a small-scale (1/8 scale factor) experimental program. The logistical and financial advantages of small-scale testing were utilized to investigate a range of parameters, including the effect of reinforcement ratio and material properties, on the response of reinforced concrete and reinforced ECC structures. The procedures pertaining to material preparation, specimen construction, and input motion development that were critical for enhancing the similarity between the scales are provided. Engineered cementitious composite mixtures with different cost and sustainability indices were evaluated. Under cyclic loading, the stiffness, strength, ductility, and energy absorption capacity of columns made of different ECC mixtures were found to be 110, 65, 45, and 100% higher, respectively, than those of the RC columns. The system level investigation through hybrid simulation showed that the ECC structures sustain less deformation under earthquake excitation due to high energy absorption capacity of the material. The differences in cost, sustainability, and structural performance of different ECC mixtures suggest that a careful selection of materials is required for optimal performance.

scholarly journals Numerical Modeling of Unreinforced Masonry Walls Strengthened with Fe-Based Shape Memory Alloy Strips

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2961
Author(s):  
Moein Rezapour ◽  
Mehdi Ghassemieh ◽  
Masoud Motavalli ◽  
Moslem Shahverdi
Keyword(s):  
Energy Dissipation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Unreinforced Masonry ◽  
Masonry Wall ◽  
Masonry Walls ◽  
Vertical Strip ◽  
Maximum Resistance ◽  
The Cross ◽  
Post Tensioning

This study presents a new way to improve masonry wall behavior. Masonry structures comprise a significant part of the world’s structures. These structures are very vulnerable to earthquakes, and their performances need to be improved. One way to enhance the performances of such types of structures is the use of post-tensioning reinforcements. In the current study, the effects of shape memory alloy as post-tensioning reinforcements on originally unreinforced masonry walls were investigated using finite element simulations in Abaqus. The developed models were validated based on experimental results in the literature. Iron-based shape memory alloy strips were installed on masonry walls by three different configurations, namely in cross or vertical forms. Seven macroscopic masonry walls were modeled in Abaqus software and were subjected to cyclic loading protocol. Parameters such as stiffness, strength, durability, and energy dissipation of these models were then compared. According to the results, the Fe-based strips increased the strength, stiffness, and energy dissipation capacity. So that in the vertical-strip walls, the stiffness increases by 98.1%, and in the cross-strip model's position, the stiffness increases by 127.9%. In the vertical-strip model, the maximum resistance is equal to 108 kN, while in the end cycle, this number is reduced by almost half and reaches 40 kN, in the cross-strip model, the maximum resistance is equal to 104 kN, and in the final cycle, this number decreases by only 13.5% and reaches 90 kN. The scattering of Fe-based strips plays an important role in energy dissipation. Based on the observed behaviors, the greater the scattering, the higher the energy dissipation. The increase was more visible in the walls with the configuration of the crossed Fe-based strips.

Seismic performance of reinforced engineered cementitious composite shear walls

2014 ◽  
Vol 7 (5) ◽  
pp. 691-704 ◽  
Author(s):  
Mo Li ◽  
Hieu C. Luu ◽  
Chang Wu ◽  
Y.L. Mo ◽  
Thomas T.C. Hsu
Keyword(s):  
Seismic Performance ◽  
Shear Walls ◽  
Cementitious Composite ◽  
Engineered Cementitious Composite ◽  
Composite Shear

Enhancing the out-of-plane behaviour of unreinforced masonry walls under impact loading through the use of partially bonded layers of engineered cementitious composite

2019 ◽  
Vol 11 (2) ◽  
pp. 209-234
Author(s):  
Saeed Pourfalah ◽  
Demetrios M Cotsovos
Keyword(s):  
Impact Loading ◽  
Composite Layer ◽  
Unreinforced Masonry ◽  
Masonry Walls ◽  
Full Potential ◽  
Cementitious Composite ◽  
Premature Failure ◽  
Engineered Cementitious Composite ◽  
Composite Layers ◽  
Out Of Plane

Published experimental work reveals that the out-of-plane behaviour of unreinforced masonry walls under impact loading can be significantly enhanced through the use of engineered cementitious composite layers fully bonded to the surface of the masonry. The disadvantage of this method is associated with the localised cracking exhibited by the engineered cementitious composite layer close to the joints forming between bricks. This cracking is associated with the bond developing between the masonry and the engineered cementitious composite layer and does not allow the latter layer to achieve its full potential, thus resulting in its premature failure. In an attempt to address this problem, a series of drop-weight tests were carried on masonry prismatic specimens strengthened with a layer of engineered cementitious composite partially bonded to the surface of the masonry acting in tension. The latter prismatic specimens consist of a stack of bricks connected with mortar joints. The specimens are considered to provide a simplistic representation of a vertical strip of a masonry wall subjected to out-of-plane actions associated with impact or blast loading. Analysis of the test data reveals that under impact loading, the specimens retrofitted with partially bonded engineered cementitious composite layers can exhibit a more ductile performance compared to that exhibited by the same specimens when strengthened with fully bonded layers of engineered cementitious composite. This is attributed to the fact that along its unbonded length, the engineered cementitious composite layer is subjected to purely uniaxial tension (free from any interaction with the surface of the masonry), allowing for the development of multiple uniformly distributed fine cracks.

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