Browsing by Author "Paslar, Nima"

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    Effects of Infill Plate’s Interconnection and Boundary Element Stiffness on Steel Plate Shear Walls’ Seismic Performance
    Paslar, Nima; Farzampour, Alireza (Materials, 2023-01-15)
    Steel plate shear walls (SPSWs) are among the most desirable load-bearing systems, which have been used wildly in various structures. Recently, designers have tended to SPSWs with only beam connections showing several problems. In the present research, several SPSWs with vari-ous types of connection conditions between infill plate and boundary elements, and various stiffness of boundary elements have been studied. The result illustrates that by having the full connection between infill plate and boundary elements, at least a 33% interconnected infill plate to columns could eliminate the significant loss of fundamental factors in SPSWs connected to beam only. Furthermore, increasing the stiffness of columns has more effect on the performance of SPSWs in comparison with beams.
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    Experimental Investigation of Sound Transmission Loss in Concrete Containing Recycled Rubber Crumbs
    Chalangaran, Navid; Farzampour, Alireza; Paslar, Nima; Fatemi, Hadi (Technopress, 2021-05-15)
    This study represents procedures and material to improve sound transmission loss through concrete without having any significant effects on mechanical properties. To prevent noise pollution damaging effects, and for reducing the transmission of the noises from streets to residential buildings, sound absorbing materials could be effectively produced. For this purpose, a number of several mixture designs have been investigated in this study to reduce the sound transmission through concrete, including control sample and three mixtures with recycled rubber with sizes of from 1mm up to 3 mm to limit the sound transmission. The rubber is used as a replacement of 5, 10, and 15 percent of sand aggregates. First, 7, 14 and 28-day strengths of the concrete have been measured. Subsequently, the sound transmission losses through the samples have been measured at the range of 63 Hz up to 6300 Hz by using impedance tube and the transfer function. The results show specimens containing 15% fine-grained crumbs, the loss of sound transmission were up to 190%, and for samples with 15% coarse-grained rubber, the loss of sound transmission were up to 228%, respectively. It is shown that concrete with recycled rubber crumbs could effectively improve environmental noise absorption.
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    Investigation of the beams and columns connection with infill plate on the structural behavior of the steel plate shear walls
    Paslar, Nima; Farzampour, Alireza (University of Tokyo, Japan, 2019-10-14)
    Steel plate shear walls are commonly used as structural lateral load resisting load systems in space-constrained areas. Many studies indicated that the implementation of the steel plate shear walls improves the ductility, stiffness and ultimate strength of the structure for which the interconnection of the steel infill plate with boundary members has a significant role. The typical connection of the infill shear plates to the boundary elements has a high-level fixity despite the general convenient construction procedures. In this study, the connection of the infill plates to the boundary elements are precisely investigated by establishing more than 21 computational models after verifying the modeling methodology. The structural performance of the partially connected plates with different commonly used connections types are evaluated and compared to the corresponding conventional fully connected infill plate systems. It is shown that column-only connected infill plate shear wall reduces the structural lateral load resisting capacity tangibly more than beam-only connected infill plates due to limited tension field action development. In addition, results indicated that systems with partial infill plate connection and connectivity ratio of 80% or more generally have similar structural performance compared to conventional systems with full connected infill plates.
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    Investigations on The Structural Behavior of Steel Plate Shear Walls with Partially Interconnected Infill Plates
    Paslar, Nima; Farzampour, Alireza; Chalangaran, Navid; Mansouri, Iman; Wan Hu, Jong (2023-07-08)
    Steel plate shear walls are considered an effective lateral load-resisting system widely used in space-constrained high-rise buildings. Steel plate shear walls could improve several structural parameters such as strength, energy absorption, and stiffness. Recently, there is a tendency to have limited connection between the infill plate and boundary elements to prevent significant direct demands on columns, and possible brittle modes of behavior leading to the economical design of various structural elements. However, previous studies showed that the absence of the interconnection between infill plate and columns in steel plate shear walls with beam-connected systems could reduce the performance of the system significantly. In the present study, procedures to improve the performance of the steel plate shear walls with limited infill plate interconnections with the boundary elements are provided. Subsequently, computational steel plate shear wall models, with and without boundary infill plate stiffeners and different widths of the infill plate have been investigated after fully validating the computational modeling methodology to find efficient procedures for eliminating the lack of interconnections. The results show that utilizing boundary stiffeners increased ultimate strength, energy dissipation and stiffness by 15%, 20%, and 24% on average. Although boundary stiffeners cannot fully control the out-of-plane displacements of the infill plate, they would be useful in improving the formation of tension field actions. Furthermore, it is shown that the width of the infill plate and boundary stiffeners are the key factors in the performance of the system.
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    Nano Silica and Metakaolin Effects on the Behavior of Concrete Containing Rubber Crumbs
    Chalangaran, Navid; Farzampour, Alireza; Paslar, Nima (MDPI, 2020-11-08)
    The excessive production of worn tires remaining from the transportation system and the lack of proper procedures to recycle or reuse these materials have caused critical environmental issues. Due to the rubber’s toughness, this material could be implemented to increase concrete toughness, and by crushing the tires concrete aggregates can be replaced proportionally with rubber crumbs and large quantities of scrapped rubber. However, this substitution decreases the concrete strength. In this study, crushed rubber with sizes from 1 to 3 mm and 3 to 6 mm were replaced by 5%, 10%, and 15% sand; the combination of two additives of nano silica and metakaolin additives with optimum values was used to compensate the degradation of the strength and improve the workability of the concrete. Moreover, the compressive strength, tensile behavior, and modulus of elasticity were measured and compared. The results indicate that the optimum use of nano silica and metakaolin additives could compensate the negative effects of the rubber material implementation in the concrete mixture while improving the overall workability and flowability of the concrete mixture.