TA570 : Performance evaluation of the concrete shear wall equipped with a hybrid damper of steel cantilever and SMA element
Thesis > Central Library of Shahrood University > Civil & Architectural Engineering > MSc > 2021
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Abstarct: One of the lateral bearing systems in reinforced concrete structures is a shear wall. In this lateral bearing system, depending on the force of the earthquake, severe damage to the wall may occur. Which may not be economically viable or impossible to improve or repair. In addition to the damage caused, after the earthquake, deformation of the residual occurs in the structure, which may cause insecurity in the residents. Researchers have used replaceable members such as steel dampers and shape memory alloys to eliminate these dilemmas. Steel dampers act as a fuse in the structure and can dissipation a lot of energy by entering the inelastic zone, also, they can be easily replaced after an earthquake. Shape memory alloy has the unique capability of Superelastic behavior and shape memory. The superelastic behavior allows the shape memory alloy to have a residual strain of about zero at large strains. In this research, to reduce the permanent deformations of the shear wall, a nickel-titanium shape memory alloy has been used. This research will answer the question of how much and with what characteristics the residual displacement of the concrete shear wall can be reduced by using the superelastic behavior of shape memory alloy. Since the stress-strain diagram of a shape memory alloy has a flag-shape in its superelastic behavior, it does not have a high energy dissipation potential, so a cantilever-type steel damper was used to absorb the seismic energy. The main purpose and idea of numerical modeling in the present study are to investigate the various aspects of modeling and the ability of the finite element model presented in predicting different results of structural analysis including displacement, strain, and cyclic behavior. In most numerical modeling comparisons of the results of numerical and laboratory models, only the force-displacement results are compared. However, the fundamental question arises as to whether the mere adaptation of the force-displacement behavior of a numerical and laboratory model can guarantee the correct performance of a numerical model. The purpose of the present analysis is a critical study to answer this question. For this purpose, while examining various aspects of numerical modeling, including material modeling assumptions, behavioral models, elements used, and solution methods, various laboratory results were discussed and interpreted with the numerical model. In this study, concrete shear walls equipped with steel damper, isolator, and SMA bar with angles of 30, 45, and 60 degree were modeled in Abaqus analytical software. Due to the complexity of the problem, three reference articles were used to validate the results of numerical modeling. In this research, 20 models with different conditions were modeled. In the model with the bar at an angle of 30 degree, the force increased the maximum and the displacement of the residual decreased the most, and in the model with the bar at an angle of 60 degree, the dissipated energy had the highest increase. Comparing the samples without SMA bar and the samples with SMA bar, the results showed that despite the positive effect of SMA bar, which leads to maximum force increase and reduced residual displacement, the dissipation energy decreases.
Keywords:
#Structural fuse #steel damper #concrete shear wall #shape memory alloy #residual displacement Keeping place: Central Library of Shahrood University
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