Browsing by Author "Mortazavi, Seyed Javad"

Now showing 1 - 8 of 8
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    Development of Innovative Lateral Resistance Systems Featuring Earthquake-Protective Dampers
    Farzampour, Alireza; Mansouri, Iman; Mortazavi, Seyed Javad; Retzepis, Eleni; Kaloop, Mosbeh R.; Hu, Jong-Wan (MDPI, 2023-03-17)
    Several conventional structural systems require sufficient retrofitting design procedures, improvements, and reconstructions to withstand lateral loads and to decrease the occurrence of damage. High strength capacity and ductility for seismic lateral resisting systems improve the structural vulnerabilities and limit damage concentrations in areas subject to seismic conditions. Several types and shapes of structural systems with appropriate ductility and energy dissipation features are currently established as structural fuses to enhance the general performance of the structures and decrease seismic ramifications. To enhance the energy dissipation performance and concentration of the inelasticity, improving the ductile behavior and limiting the unpredictable accumulation of plastic strains is essential. The conventional eccentrically braced systems are examined and reestablished, and the effects of shear fuses used in high-rise buildings are investigated for prototype buildings by implementing the verified simulations. Next, seismic protective fuse systems with innovative dampers consisting of several butterfly-shaped shear links are established. Ultimately, the design guidelines are established based on the conventional eccentrically braced frames (EBFs), which are redesigned with the use of noble seismic protective fuses, and the hysteretic behavior is obtained and compared accordingly.
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    Force-displacement behavior of a beam with butterfly-shaped dampers implementing GE programming
    Farzampour, Alireza; Mansouri, Iman; Mortazavi, Seyed Javad; Hu, Jong Wan (Springer, 2020)
    Structural steel plates having engineered cut-outs to exhibit controlled yielding is recently proposed for desirable performance compared to conventional systems. Butterfly-shaped beams with hexagonal cut-outs inside of the beam’s web is studied to better align the bending strength diagram along the link length with the corresponding demand shape of the applied moment diagram. In previous studies, it has been reported that these links have a substantial energy dissipation capability and sufficient ductility which necessities further investigations. In this study, a set of 240 nonlinear finite element models are developed for creation of a database and subsequently calibrated with finite element software packages. The capability of the gene expression programming (GEP) is explored for prediction of force-displacement relationship of a butterfly-shaped beam. Two new models are developed based on the reliable generated database. Subsequently, the proposed models are validated with several conducted analysis and statistical parameters, for which the comparisons are shown in details. The results represent that the proposed models are able to predict the force-displacement relationship of a butterfly-shaped beam with satisfactory accuracy.
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    Force-displacement relationship of a butterfly-shaped beams based on gene expression programming [conference proceeding]
    Farzampour, Alireza; Mansouri, Iman; Mortazavi, Seyed Javad; Hu, Jong Wan (2019-11)
    Structural steel plates having engineered cut-outs to exhibit controlled yielding is recently proposed for desirable performance compared to conventional systems. Butterfly-shaped beams with hexagonal cut-outs inside of the beam’s web is studied to better align the bending strength diagram along the link length with the corresponding demand shape of the applied moment diagram. In previous studies, it has been reported that these links have substantial energy dissipation capability and sufficient ductility which necessities further investigations. In this study, a set of 240 nonlinear finite element models are developed for creation of a database and subsequently calibrated with finite element software packages. The capability of the gene expression programming (GEP) is explored for prediction of force-displacement relationship of a butterfly-shaped beam. Two new models are developed based on the reliable generated database. Subsequently, the proposed models are validated with several conducted analysis and statistical parameters, for which the comparisons are shown in detail. The results represent that the proposed models are able to predict the force-displacement relationship of a butterfly-shaped beam with satisfactory accuracy.
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    Force-displacement relationship of the butterfly-shaped beams based on gene expression programming
    Farzampour, Alireza; Mansouri, Iman; Mortazavi, Seyed Javad; Hu, Jong Wan (Springer, 2020-09)
    Structural steel plates with engineered cut-outs to exhibit controlled yielding mechanism is recently proposed for desirable structural performance compared to conventional systems. Butterfly-shaped beams with hexagonal cut-outs inside of the beam’s web is implemented to better align the bending strength diagram along the link length with the corresponding demand shape of the applied moment diagram. In previous studies, it has been reported that these links have a substantial energy dissipation capability and sufficient ductility which necessities further investigations and structural behavior prediction studies. In this study, a set of 240 nonlinear finite element models are developed for creation of a database and subsequently calibrated with finite element software packages. The capability of the gene expression programming (GEP) is explored for prediction of force-displacement relationship of a butterfly-shaped beam. Two new models are developed based on the reliable generated database. Subsequently, the proposed models are validated with several conducted analysis and statistical parameters, for which the comparisons are shown in details. The results represent that the proposed models are able to predict the force-displacement relationship of a butterfly-shaped beam with satisfactory accuracy.
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    Multi-Story Buildings Equipped with Innovative Structural Seismic Shear Fuse Systems
    Farzampour, Alireza; Mortazavi, Seyed Javad; Mansouri, Iman; Awoyera, Paul Oluwaseun; Wan Hu, Jong (Elsevier, 2022-03-29)
    Infrastructures could be designed and constructed to resist seismic lateral loads without experiencing a significant amount of damage concentrations in specific area. Having sufficient strength and stiffness to reduce the structural vulnerabilities against serious damages under seismic loading, requires structural elements to have adequate ductility and energy dissipating capability, which could be provided with the use structural dampers. These elements are typically replaceable, and designed to yield and protect the surrounding members from damages, and then be accessible after a major event. In this study, butterfly-shaped links with linearly varying width between larger ends and a smaller middle section are used for redesigning the prototype structures due to substantial ductility and stable energy dissipation capability. The effect of implementation of innovative seismic dampers in multi-story structures is investigated by analyzing multi-story prototype structures with structural seismic shear dampers, and subsequently compared with simple conventional linking beams. The results of the nonlinear response history analysis are summarized for 44 ground motions under maximum considered earthquake (MCE) and designed based earthquake (DBE) hazard levels. It is shown that implementation of the butterfly-shaped dampers in buildings with similar stiffness and strength leads to higher dissipated energy and less pinched curves compared to typical eccentrically braced frame systems. It is determined that the general stiffness and strength of the system with the butterfly-shaped link is close to conventional models; however, the demands on the surrounding boundary elements are lower than the corresponding conventional model, which could be beneficent for improving the seismic performance of the structural systems.
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    Optimization of the Curved Metal Damper to Improve Structural Energy Dissipation Capacity
    Kim, Young-Chan; Mortazavi, Seyed Javad; Farzampour, Alireza; Hu, Jong Wan; Mansouri, Iman; Awoyera, Paul Oluwaseun (MDPI, 2022-01-11)
    Structural curved metal dampers are implemented in various applications to mitigate the damages at a specific area efficiently. A stable and saturated hysteretic behavior for the in-plane direction is dependent on the shape of a curved-shaped damper. However, it has been experimentally shown that the hysteretic behavior in the conventional curved-shaped damper is unstable, mainly as a result of bi-directional deformations. Therefore, it is necessary to conduct shape optimization for curved dampers to enhance their hysteretic behavior and energy dissipation capability. In this study, the finite element (FE) model built in ABAQUS, is utilized to obtain optimal shape for the curved-shaped damper. The effectiveness of the model is checked by comparisons of the FE model and experimental results. The parameters for the optimization include the curved length and shape of the damper, and the improved approach is conducted by investigating the curved sections. In addition, the design parameters are represented by B-spline curves (to ensure enhanced system performance), regression analysis is implemented to derive optimization formulations considering energy dissipation, constitutive material model, and cumulative plastic strain. Results determine that the energy dissipation capacity of the curved steel damper could be improved by 32% using shape optimization techniques compared to the conventional dampers. Ultimately, the study proposes simple optimal shapes for further implementations in practical designs.
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    Optimization of the curved metal damper to improve structural energy dissipation capacity
    Kim, Young-Chan; Mortazavi, Seyed Javad; Farzampour, Alireza; Hu, Jong Wan; Mansouri, Iman; Awoyera, Paul Oluwaseun (MDPI, 2022-01-15)
    Structural curved metal dampers are implemented in various applications to mitigate the damages at a specific area efficiently. A stable and saturated hysteretic behavior for the in-plane direction is dependent on the shape of a curved-shaped damper. However, it has been experi-mentally shown that the hysteretic behavior in the conventional curved-shaped damper is un-stable, mainly as a result of bi-directional deformations. Therefore, it is necessary to conduct shape optimization for curved dampers to enhance their hysteretic behavior and energy dissipa-tion capability. In this study, the finite element (FE) model built in ABAQUS, is utilized to obtain optimal shape for the curved-shaped damper. The effectiveness of the model is checked by com-parisons of the FE model and experimental results. The parameters for the optimization include the curved length and shape of the damper, and the improved approach is conducted by investi-gating the curved sections. In addition, the design parameters are represented by B-spline curves (to ensure enhanced system performance), regression analysis is implemented to derive optimi-zation formulations considering energy dissipation, constitutive material model, and cumula-tive plastic strain. Results determine that the energy dissipation capacity of the curved steel damper could be improved by 32% using shape optimization techniques compared to the con-ventional dampers. Ultimately, the study proposes simple optimal shapes for further imple-mentations in practical designs.
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    Symposium: Butterfly-Shaped Beams Relationship with GEP
    Farzampour, Alireza; Mansouri, Iman; Mortazavi, Seyed Javad; Hu, Jong Wan (2019)
    Structural steel plates having engineered cut-outs to exhibit controlled yielding is recently proposed for desirable performance compared to conventional systems. Butterfly-shaped beams with hexagonal cut-outs inside of the beam’s web is studied to better align the bending strength diagram along the link length with the corresponding demand shape of the applied moment diagram. In previous studies, it has been reported that these links have a substantial energy dissipation capability and sufficient ductility which necessities further investigations. In this study, a set of 240 nonlinear finite element models are developed for creation of a database and subsequently calibrated with finite element software packages. The capability of the gene expression programming (GEP) is explored for prediction of force-displacement relationship of a butterfly-shaped beam. Two new models are developed based on the reliable generated database. Subsequently, the proposed models are validated with several conducted analysis and statistical parameters, for which the comparisons are shown in details. The results represent that the proposed models are able to predict the force-displacement relationship of a butterfly-shaped beam with satisfactory accuracy.