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Amir Ayazi - One of the best experts on this subject based on the ideXlab platform.

  • concrete stiffened steel plate shear walls with an unstiffened opening
    Structures, 2017
    Co-Authors: Soheil Shafaei, Farhang Farahbod, Amir Ayazi
    Abstract:

    Abstract In this study, nonlinear behavior of concrete stiffened steel plate shear wall (CSPSW) with an opening is investigated. The study is divided into two separate parts in order to understand the effect of an unstiffened opening—locations and sizes. In phase one: four square opening sizes—small, medium, large, and very large—are selected to study the location of the opening. When the size of square opening is fixed, the location is changed over the infill wall. The pattern is also repeated with a new square size. In phase two: shear walls with a centrally located circular opening are considered and the opening ratio varies from 10% to 65%. In the study, the degradations of seismic factors —the Initial Stiffness, the ultimate shear strength, the ductility ratio, and the energy absorption— in terms of opening ratio are calculated. According to obtained results, the behavior of CSPSWs with an opening is utterly different from corresponding SPSWs. Initial Elastic Stiffness of CSPSWs with an opening is independent of the opening location and ultimate shear strength is slightly affected by location. Moreover, a linear degradation in the Initial Elastic Stiffness and the ultimate shear strength of the infill composite wall is observed due to increasing the opening ratio.

  • the effect of concrete panel thickness upon composite steel plate shear walls
    Journal of Constructional Steel Research, 2016
    Co-Authors: Soheil Shafaei, Amir Ayazi, Farhang Farahbod
    Abstract:

    Abstract In this study, the analytical study of concrete stiffened steel plate shear wall (CSPSW) with a reinforced concrete panel on one side and with gap between the concrete panel and steel frame is conducted. CSPSWs have a variety of infill steel plate and reinforced concrete panel thicknesses. The results show that the behavior of CSPSWs and corresponding steel plate shear walls (SPSWs) is utterly disparate. The infill steel plate of SPSW resists lateral load by development of tension fields, as the infill steel plate initiates Elastic buckling. However, in CSPSW, the Elastic buckling of the infill steel plate is prevented by the introduction of the reinforced concrete panel; hence, the infill steel plate carries out lateral load by pure shear yield. Moreover, during the lateral load, CSPSW undergoes four stages: Initial Elastic Stiffness, shear yield Stiffness, post-shear yielding Stiffness, and pre-failure Stiffness. The reinforced concrete panel thickness has a remarkable and direct influence upon the shear capacity and the ultimate strength of the CSPSW; furthermore, it is dependent upon the thickness of infill steel plate. Increasing the concrete panel thickness up to a specific value, the shear capacity and the ultimate strength enhance; however, while increasing it beyond that, the shear capacity and the ultimate shear strength of CSPSW remain constant. CSPSW provides a higher Initial Elastic Stiffness, greater shear capacity, and higher ultimate strength as compared to its corresponding SPSW. The ductility ratio and energy absorption of CSPSW is improved owing to introduction of reinforced concrete panel as well.

Soheil Shafaei - One of the best experts on this subject based on the ideXlab platform.

  • concrete stiffened steel plate shear walls with an unstiffened opening
    Structures, 2017
    Co-Authors: Soheil Shafaei, Farhang Farahbod, Amir Ayazi
    Abstract:

    Abstract In this study, nonlinear behavior of concrete stiffened steel plate shear wall (CSPSW) with an opening is investigated. The study is divided into two separate parts in order to understand the effect of an unstiffened opening—locations and sizes. In phase one: four square opening sizes—small, medium, large, and very large—are selected to study the location of the opening. When the size of square opening is fixed, the location is changed over the infill wall. The pattern is also repeated with a new square size. In phase two: shear walls with a centrally located circular opening are considered and the opening ratio varies from 10% to 65%. In the study, the degradations of seismic factors —the Initial Stiffness, the ultimate shear strength, the ductility ratio, and the energy absorption— in terms of opening ratio are calculated. According to obtained results, the behavior of CSPSWs with an opening is utterly different from corresponding SPSWs. Initial Elastic Stiffness of CSPSWs with an opening is independent of the opening location and ultimate shear strength is slightly affected by location. Moreover, a linear degradation in the Initial Elastic Stiffness and the ultimate shear strength of the infill composite wall is observed due to increasing the opening ratio.

  • the effect of concrete panel thickness upon composite steel plate shear walls
    Journal of Constructional Steel Research, 2016
    Co-Authors: Soheil Shafaei, Amir Ayazi, Farhang Farahbod
    Abstract:

    Abstract In this study, the analytical study of concrete stiffened steel plate shear wall (CSPSW) with a reinforced concrete panel on one side and with gap between the concrete panel and steel frame is conducted. CSPSWs have a variety of infill steel plate and reinforced concrete panel thicknesses. The results show that the behavior of CSPSWs and corresponding steel plate shear walls (SPSWs) is utterly disparate. The infill steel plate of SPSW resists lateral load by development of tension fields, as the infill steel plate initiates Elastic buckling. However, in CSPSW, the Elastic buckling of the infill steel plate is prevented by the introduction of the reinforced concrete panel; hence, the infill steel plate carries out lateral load by pure shear yield. Moreover, during the lateral load, CSPSW undergoes four stages: Initial Elastic Stiffness, shear yield Stiffness, post-shear yielding Stiffness, and pre-failure Stiffness. The reinforced concrete panel thickness has a remarkable and direct influence upon the shear capacity and the ultimate strength of the CSPSW; furthermore, it is dependent upon the thickness of infill steel plate. Increasing the concrete panel thickness up to a specific value, the shear capacity and the ultimate strength enhance; however, while increasing it beyond that, the shear capacity and the ultimate shear strength of CSPSW remain constant. CSPSW provides a higher Initial Elastic Stiffness, greater shear capacity, and higher ultimate strength as compared to its corresponding SPSW. The ductility ratio and energy absorption of CSPSW is improved owing to introduction of reinforced concrete panel as well.

Farhang Farahbod - One of the best experts on this subject based on the ideXlab platform.

  • concrete stiffened steel plate shear walls with an unstiffened opening
    Structures, 2017
    Co-Authors: Soheil Shafaei, Farhang Farahbod, Amir Ayazi
    Abstract:

    Abstract In this study, nonlinear behavior of concrete stiffened steel plate shear wall (CSPSW) with an opening is investigated. The study is divided into two separate parts in order to understand the effect of an unstiffened opening—locations and sizes. In phase one: four square opening sizes—small, medium, large, and very large—are selected to study the location of the opening. When the size of square opening is fixed, the location is changed over the infill wall. The pattern is also repeated with a new square size. In phase two: shear walls with a centrally located circular opening are considered and the opening ratio varies from 10% to 65%. In the study, the degradations of seismic factors —the Initial Stiffness, the ultimate shear strength, the ductility ratio, and the energy absorption— in terms of opening ratio are calculated. According to obtained results, the behavior of CSPSWs with an opening is utterly different from corresponding SPSWs. Initial Elastic Stiffness of CSPSWs with an opening is independent of the opening location and ultimate shear strength is slightly affected by location. Moreover, a linear degradation in the Initial Elastic Stiffness and the ultimate shear strength of the infill composite wall is observed due to increasing the opening ratio.

  • the effect of concrete panel thickness upon composite steel plate shear walls
    Journal of Constructional Steel Research, 2016
    Co-Authors: Soheil Shafaei, Amir Ayazi, Farhang Farahbod
    Abstract:

    Abstract In this study, the analytical study of concrete stiffened steel plate shear wall (CSPSW) with a reinforced concrete panel on one side and with gap between the concrete panel and steel frame is conducted. CSPSWs have a variety of infill steel plate and reinforced concrete panel thicknesses. The results show that the behavior of CSPSWs and corresponding steel plate shear walls (SPSWs) is utterly disparate. The infill steel plate of SPSW resists lateral load by development of tension fields, as the infill steel plate initiates Elastic buckling. However, in CSPSW, the Elastic buckling of the infill steel plate is prevented by the introduction of the reinforced concrete panel; hence, the infill steel plate carries out lateral load by pure shear yield. Moreover, during the lateral load, CSPSW undergoes four stages: Initial Elastic Stiffness, shear yield Stiffness, post-shear yielding Stiffness, and pre-failure Stiffness. The reinforced concrete panel thickness has a remarkable and direct influence upon the shear capacity and the ultimate strength of the CSPSW; furthermore, it is dependent upon the thickness of infill steel plate. Increasing the concrete panel thickness up to a specific value, the shear capacity and the ultimate strength enhance; however, while increasing it beyond that, the shear capacity and the ultimate shear strength of CSPSW remain constant. CSPSW provides a higher Initial Elastic Stiffness, greater shear capacity, and higher ultimate strength as compared to its corresponding SPSW. The ductility ratio and energy absorption of CSPSW is improved owing to introduction of reinforced concrete panel as well.

Izuru Etakewaki - One of the best experts on this subject based on the ideXlab platform.

  • Closed-form dynamic stability criterion for Elastic-plastic structures under near-fault ground motions
    Frontiers Media S.A., 2016
    Co-Authors: Kotaro Ekojima, Izuru Etakewaki
    Abstract:

    A dynamic stability criterion for Elastic-plastic structures under near-fault ground motions is derived in closed-form. A negative post-yield Stiffness is treated in order to consider the P-delta effect. The double impulse is used as a substitute of the fling-step near-fault ground motion. Since only the free-vibration appears under such double impulse, the energy approach plays a critical role in the derivation of the closed-form solution of a complicated Elastic-plastic response of structures with the P-delta effect. It is remarkable that no iteration is needed in the derivation of the closed-form dynamic stability criterion on the critical Elastic-plastic response. It is shown via the closed-form expression that several patterns of unstable behaviors exist depending on the ratio of the input level of the double impulse to the structural strength and on the ratio of the negative post-yield Stiffness to the Initial Elastic Stiffness. The validity of the proposed dynamic stability criterion is investigated by the numerical response analysis for structures under double impulses with stable or unstable parameters. Furthermore the reliability of the proposed theory is tested through the comparison with the response analysis to the corresponding one-cycle sinusoidal input as a representative of the fling-step near-fault ground motion. The applicability of the proposed theory to actual recorded pulse-type ground motions is also discussed

Takewaki Izuru - One of the best experts on this subject based on the ideXlab platform.

  • Closed-Form Dynamic Stability Criterion for Elastic–Plastic Structures under Near-Fault Ground Motions
    'Frontiers Media SA', 2016
    Co-Authors: Kojima Kotaro, Takewaki Izuru
    Abstract:

    A dynamic stability criterion for Elastic–plastic structures under near-fault ground motions is derived in closed form. A negative post-yield Stiffness is treated in order to consider the P-delta effect. The double impulse is used as a substitute of the fling-step near-fault ground motion. Since only the free vibration appears under such double impulse, the energy approach plays a critical role in the derivation of the closed-form solution of a complicated Elastic–plastic response of structures with the P-delta effect. It is remarkable that no iteration is needed in the derivation of the closed-form dynamic stability criterion on the critical Elastic–plastic response. It is shown via the closed-form expression that several patterns of unstable behaviors exist depending on the ratio of the input level of the double impulse to the structural strength and on the ratio of the negative post-yield Stiffness to the Initial Elastic Stiffness. The validity of the proposed dynamic stability criterion is investigated by the numerical response analysis for structures under double impulses with stable or unstable parameters. Furthermore, the reliability of the proposed theory is tested through the comparison with the response analysis to the corresponding one-cycle sinusoidal input as a representative of the fling-step near-fault ground motion. The applicability of the proposed theory to actual recorded pulse-type ground motions is also discussed