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فهرست مطالب نویسنده:

a. sivandi pour

  • R. Khandan, A. Sivandipour, E. Noroozinejad Farsangi

    This study presents novel research on the seismic behavior of self-centering reduced beam section (RBS) connections in steel structures. Unlike traditional moment steel frames that concentrate non-elastic deformations in energy dissipation devices, the innovative self-centering RBS connections utilize post-tensioning techniques to restore the structure to its pre-earthquake condition. By significantly reducing residual deformations, these connections offer a promising alternative for improving seismic resilience. To validate the effectiveness of the post-tensioned (PT) and RBS connections, advanced nonlinear numerical modeling using the Finite Element Method (FEM) in ABAQUS software is employed. This approach allows for a comprehensive investigation, comparing the numerical results with laboratory data. Furthermore, the study goes beyond existing research by incorporating additional high-strength cables into the RBS connections. This novel configuration aims to assess the impact of post-tensioned cables on seismic behavior, adding a new dimension to the understanding of these connections. Through a rigorous parametric study, the research uncovers crucial insights into the seismic performance of the self-centering RBS connections. Notably, the study reveals the significant influence of the initial post-tensioning force on various aspects, including stiffness, maximum moment capacity, and gap-opening behavior of PT connections. The findings demonstrate the potential of increasing the initial post-tensioning force to enhance the energy dissipation capacity and overall performance of the PT connections. Overall, this study presents pioneering research that advances the understanding of self-centering RBS connections and their potential application in steel structures. By emphasizing the novel aspects of the research, it contributes to the body of knowledge in the field and provides valuable insights for improving the seismic resilience of structures.

    Keywords: Post-tensioned Connections, Self-centering Connections, Reduced Section Beam Connections, Seismic Resilience, Finite Element Method
  • R. Zomorodian, F. Soltani, A. Sivandi Pour, E. Noroozinejad Farsangi *

    In this study, the seismic performance of a 20-storey steel structure with a mat foundation located on layered soil is investigated under an array of strong ground excitations, which includes 6 far-fault and 6 near-fault earthquakes. Eight different modes for soil layering have been considered in the numerical simulation. FLAC 2D nonlinear platform has been used to model the near-realistic behavior. To this end, hundred lines of codes and sub-routines have been developed in this platform to perform the analysis. The results of the analyzes include the absolute displacement of the floors, the ratio of the relative displacement of the floors, the shear force, the axial force, and the bending moment of the columns. It was concluded that for a 20-story structure on a mat foundation under both far-field and near-field earthquakes, the most reliable type of soil is the dense sandy soil and the most critical case is the soft clay soil. It was also observed that the near-field strong ground motions have imposed more critical structural responses compared to far-field records.

    Keywords: High-Rise Structure, Foundation Flexibility, Storey Displacement, Layered Soils, Far-field, Near-field
  • امیرحسین نوروزی، محسن گرامی*، رضا وهدانی، عباس سیوندی پور

    آثار هم زمان خاک و چندین سازه، به عنوان اندرکنش شهر - ساختگاه (سازه - خاک - سازه) شناخته می شود، که در مناطق با تراکم ساختمانی زیاد، بسیار مهم است. به دلیل انتشار امواج بین سازه ها، لحاظ اثر اندرکنش شهر - ساختگاه باعث تغییر در پاسخ ها می شود. در بررسی موضوع اخیر، پارامترهای زیادی، از جمله: جنس خاک، میزان تراکم و نظم ساختاری شهری، ارتفاع ساختمان ها، شکل امواج زلزله و دوره ی تناوب اصلی سازه ها و خاک تاثیر دارند. در پژوهش حاضر، آثار نوع خاک (تیپ بندی استاندارد 2800) و فواصل ساختمان ها بر روی این موضوع در پاسخ های بالای سازه و فونداسیون به صورت سه بعدی بررسی شده است. با توجه به نتایج به دست آمده می توان این نکته را بیان کرد که وجود سازه ها در کنار یکدیگر با لحاظ اثر اندرکنش شهر - ساختگاه در خاک های مختلف موجب کاهش پاسخ های شتاب سازه)میانگین 25٪(نسبت به حالت سازه ی منفرد می شود.

    کلید واژگان: اندرکنش چندگانه ی سازه - خاک - سازه، آثار شهر، میزان سختی خاک، اندرکنش شهر - ساختگاه، انتشار امواج زلزله
    A.H. Norouzi, M. Gerami *, R. Vahdani, A. Sivandi Pour

    Simultaneous effects of soil and several structures are known as the site-city interaction (structure-soil-structure interaction), which is very important in areas with high construction density and has been considered by many scholars over the past two decades. Site-city interaction can affect the structure behavior due to the wave propagation between structures. In fact, it decreases the structure responses in some cases, while it increases the responses in some other cases. Many parameters play a role in assessing site-city interaction such as the gender of soil, number and arrangement of structures, height of buildings, shape of earthquake waves, and the main period of structures and soil. The present study aimed to evaluate the effects of gender and solidity of the soil based on 2800 standards and building distances in site-city interaction in three dimensions. The effects of these parameters on the foundation and top of structure responses including maximum acceleration values and Root Mean Square acceleration were assessed. SASSI 2000 software was employed to model structures and soil and analyze the system. In this study, structural models were considered in both single structure and the ideal city (structural groups). The groups were 3times3 including nine identical structures. In the single model, the site-city interaction was not considered, and these effects were considered in the group model. Lumped-Mass Stick Model was used to model each structure and the soil, which was modeled in the software including a semi-infinite elastic environment with horizontal layering, located on the viscoelastic half-infinitely semi-space. Based on the results, regarding the top of structure, the existence of structures alongside each other by considering site-city interaction effects in different soils resulted in decreasing the structural acceleration responses (25% average) compared to the individual structure site-city interaction effects, which increased by decreasing the soil stiffness (5-10% average). Further, the effects of multiple structure-soil-structure interaction decreased (10-15% average) by increasing the distance between structures.

    Keywords: Multiple Structure - Soil - Structure Interaction, City Effects, Soil Solidity Order, Site-City Interaction, Waves Propagation
  • A. H. Norouzi, M. Gerami *, R. Vahdani, A. Sivandi Pour

    The simultaneous effects of soil and existing structures are known as the site-city interaction (structure-soil-structure). The impact of site-city interaction on structure behavior is effective. Thus, this interaction in some regions decreases the responses while increases in other areas. In addition, the site-city interaction of many parameters including the soil type, density rate, height of buildings is effective for evaluation. So far, none of investigation has focused on the effects of nature and shape of seismic wave and the plate which affects these waves in site-city interaction in three dimensions. Thus, the present study aimed to consider the effect of parameters mentioned in structure and foundation responses. The results indicated that the highest reduction for Love wave occurs in acceleration responses of structure in the cluster relative to the individual state, compared to the rest of the waves. Therefore, the reduction is about 30 and 50% for the base and top nodes of structures, respectively.

    Keywords: Must Soil, structure Interaction Earthquake Waves Site, City Interaction Seismic Excitation Waves Propagation
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