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.

scholarly journals Experimental and Numerical Analysis of the Mechanical Properties of a Pretreated Shape Memory Alloy Wire in a Self-Centering Steel Brace

Processes ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 80
Author(s):  
Bo Zhang ◽  
Sizhi Zeng ◽  
Fenghua Tang ◽  
Shujun Hu ◽  
Qiang Zhou ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Energy Dissipation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Loading Rate ◽  
Effective Elastic Modulus ◽  
Maximum Energy ◽  
Numerical Results ◽  
Energy Dissipation Capacity

As a stimulus-sensitive material, the difference in composition, fabrication process, and influencing factors will have a great effect on the mechanical properties of a superelastic Ni-Ti shape memory alloy (SMA) wire, so the seismic performance of the self-centering steel brace with SMA wires may not be accurately obtained. In this paper, the cyclic tensile tests of a kind of SMA wire with a 1 mm diameter and special element composition were tested under multi-working conditions, which were pretreated by first tensioning to the 0.06 strain amplitude for 40 cycles, so the mechanical properties of the pretreated SMA wires can be simulated in detail. The accuracy of the numerical results with the improved model of Graesser’s theory was verified by a comparison to the experimental results. The experimental results show that the number of cycles has no significant effect on the mechanical properties of SMA wires after a certain number of cyclic tensile training. With the loading rate increasing, the pinch effect of the hysteresis curves will be enlarged, while the effective elastic modulus and slope of the transformation stresses in the process of loading and unloading are also increased, and the maximum energy dissipation capacity of the SMA wires appears at a loading rate of 0.675 mm/s. Moreover, with the initial strain increasing, the slope of the transformation stresses in the process of loading is increased, while the effective elastic modulus and slope of the transformation stresses in the process of unloading are decreased, and the maximum energy dissipation capacity appears at the initial strain of 0.0075. In addition, a good agreement between the test and numerical results is obtained by comparing with the hysteresis curves and energy dissipation values, so the numerical model is useful to predict the stress–strain relations at different stages. The test and numerical results will also provide a basis for the design of corresponding self-centering steel dampers.

The cyclic response of circular reinforced concrete column to foundation connections strengthened with shape memory alloy bars

2020 ◽  
pp. 002199832096144
Author(s):  
Mahdieh Miralami ◽  
M Reza Esfahani ◽  
Mohammadreza Tavakkolizadeh ◽  
Reza Khorramabadi ◽  
Jalil Rezaeepazhand
Keyword(s):  
Energy Dissipation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Load Capacity ◽  
Lateral Load ◽  
Reference Specimen ◽  
Initial Stiffness ◽  
Residual Displacement ◽  
Cfrp Sheets ◽  
Column Foundation

This study presents a new method for strengthening the circular reinforced concrete (RC) column to foundation connections with shape memory alloy (SMA) bars and carbon fiber reinforced polymer (CFRP) sheets. In the experimental part of the study, three specimens of RC column-foundation connections were cast and tested. One specimen was used as the reference specimen without strengthening. Two other specimens were strengthened with longitudinal SMA bars and CFRP sheets. These specimens were under a constant axial compressive load and cyclic lateral displacements, simultaneously. Next, initial stiffness, energy dissipation capacity, lateral load capacity, ductility, and residual displacement of the specimens were investigated. Due to the superelastic behavior of SMA bars, the residual displacement of column-foundation connections was considerably less than that of the reference specimen. Compared to the reference specimen, the SMA-strengthened and SMA-CFRP-strengthened connections recovered 71.59% and 76.57% of the residual displacement. Therefore, SMA bars were able to recover residual displacements under cyclic loading. Also, the combination of the SMA bars with CFRP sheet was a promising solution for enhancing the amount of the energy dissipation, lateral load capacity, initial stiffness, and ductility parameters. Compared to the reference specimen, the energy dissipation, lateral load capacity, initial stiffness, and ductility ratio parameters of SMA-CFRP-strengthened connection increased about 43.45%, 76.20%, 81.69%, and 242.45%, respectively. In the numerical part of the study, a subroutine was applied for modeling the SMA materials. For the analysis, this subroutine was linked with ABAQUS software. The numerical results showed a close correlation with the experimental results.

11.65: An axial type self-centering energy dissipation device with shape memory alloy for seismic mitigation

ce/papers ◽  
2017 ◽  
Vol 1 (2-3) ◽  
pp. 3356-3364
Author(s):  
Ran Li ◽  
Ganping Shu ◽  
Zhen Liu ◽  
Xiao Lyu ◽  
Meihe Chen
Keyword(s):  
Energy Dissipation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Seismic Mitigation

scholarly journals Experimental Analysis of Seismic Performance of Masonry Shear Wall Reinforced with PP-Band Mesh and Plastering Mortar under In-Plane Cyclic Loading

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Qiang Zhou ◽  
Lingyu Yang ◽  
Wenyang Zhao
Keyword(s):  
Energy Dissipation ◽  
Cyclic Loading ◽  
Bearing Capacity ◽  
Low Cost ◽  
Low Frequency ◽  
Masonry Wall ◽  
Ultimate Bearing Capacity ◽  
Masonry Walls ◽  
Seismic Capacity ◽  
Energy Dissipation Capacity

Masonry structures are widely used in developing countries due to their low cost and simple construction, especially in remote areas, where there are a large number of houses without seismic measures. These buildings are prone to collapse and cause a lot of casualties, even under the action of small earthquakes. For the reinforcement of this structure, a cheap, effective, and easy-to-construct reinforcement method is urgently needed. Therefore, this article studies the reinforcement method of polypropylene bands (PP-bands). We have carried out low-frequency cyclic loading tests for two PP-band reinforced masonry walls and two compared masonry walls. We mainly studied the influence of PP-band and different compressive strengths of plastering mortar on the masonry wall’s seismic capacity. The seismic indicators mainly studied in this article include ultimate bearing capacity, energy dissipation capacity, stiffness degradation, and hysteresis characteristics. The experimental results show that the PP-band can greatly enhance the seismic capacity of the masonry wall. The ultimate bearing capacity, energy dissipation capacity, and displacement ductility of the PP-band reinforced wall are increased by 38%–48%, 22%–47%, and 138%–226%.

Nonlinear Finite Element Analysis of Masonry Wall Strengthened with Steel Strips

2013 ◽  
Vol 838-841 ◽  
pp. 284-296
Author(s):  
Yu Hua Wang ◽  
Bei Bei Wang ◽  
Pei Chi ◽  
Jun Dong
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Lateral Displacement ◽  
Unreinforced Masonry ◽  
Masonry Wall ◽  
Shear Capacity ◽  
Computational Formula ◽  
Element Analysis ◽  
Steel Strips ◽  
The Cross

The finite element analysis method was adopted to simulate the masonry wall strengthened with steel strips and was verified by comparing with test results. The influence rules of two factors including the cross sectional area of steel strips and vertical compression were investigated. The results show that, as for unreinforced masonry wall, the relationship of the shear capacity of unreinforced masonry wall and the vertical compressive strain is linear under lateral load; the speed of stiffness degeneration is accelerated after the peak point of the curves, but decrease with the increasing of lateral displacement. As for masonry wall strengthened with steel strips, the shear capacity increases significantly, and shows nonlinear relationship with the cross section area of the steel strips and vertical compression; ductility is improved. Finally, a computational formula of shear capacity based on a lot of parametric analysis is proposed to calculate the sectional dimension of steel strips, and it provides theoretical foundation for establishing thorough design method of masonry wall strengthened with steel strips.

Experimental Research of PFD-SMA Support System

2011 ◽  
Vol 71-78 ◽  
pp. 4521-4524 ◽  
Author(s):  
Ji Gang Zhang ◽  
Yan Mei Liu ◽  
Yuan Feng Gao ◽  
Jian Han
Keyword(s):  
Energy Dissipation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Support System ◽  
Load Force ◽  
Element Analysis ◽  
Test Study ◽  
Force Increase ◽  
The Finite Element Analysis ◽  
Good Energy

Pall-typed dampers(PFD) have good energy dissipation, and shape memory alloy(SMA) brace has good super-elastic performance, so the PFD-SMA support system is put forward. Through the test study of PFD-SMA support system, analyze the influence to its hysteretic characteristic by preload force of Pall-typed frictional damper, the stiffness and length parameters of shape memory alloy support. The test results show that PFD-SMA support system s have good energy dissipation and good reposition due to its super-elastic performance, with pre-load force increase, its super-elastic performance acts better, its hysteretic curve show super-elastic performance too, and it verifies the correctness of the finite element analysis.

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