IJE TRANSACTIONS C: Aspects Vol. 30, No. 9 (August 2017) 1395-1403    Article in Press

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V. R. Kalatjari, Ali Naghizadeh, R. Naderi and M. H. Talebpour
( Received: March 04, 2017 – Accepted: July 07, 2017 )

Abstract    The base level will be among the effective parameters in determining the seismic force on a structure, if the equivalent-static method is used for analyzing a structure. It is obvious that the base level is located on foundation in buildings in which foundation is built in a single level and there is not any interaction between the structure\'s walls and the soil; however, in some buildings which have underground part, the foundation is built in two different levels which in turn makes uncertain determining the location of base level. Since no relevant recommendation has been provided in the seismic codes, this study tries to remove such uncertainties. For this purpose, the structural models along with foundation and their peripheral soil were modeled by the ABAQUS software and regarding the soil type it was tested by an artificial accelerogram compatible with the spectrum of the code. Two types of soil (stiff and soft) were used in this study. The results indicated that the base level location is considerably influenced by the soil type, the number of entrance columns leading to the underground and number of stories of the structure.


Keywords    Base Level, Soil-Foundation-Structure Interaction, Different Foundation Levels, Artificial Accelerogram.


چکیده    چنانچه برای آنالیز یک سازه از روش استاتیکی معادل استفاده شود، تراز پایه از جمله پارامترهای مؤثر، در تعیین نیروی لرزه‌ای وارد بر سازه خواهد بود. در سازه‌هایی که در آنها فونداسیون در یک سطح اجرا می‌شود و هیچگونه اندرکنشی بین دیواره‌های سازه و خاک وجود ندارد، بدیهی است محل تراز پایه روی فونداسیون است؛ اما در برخی از ساختمان‌ها به دلیل وجود زیرزمین در قسمتی از سازه، فونداسیون در دو تراز متفاوت اجرا می‌شود که برای تعیین محل تراز پایه ابهاماتی به وجود آورده است. با توجه به آنکه در آیین‌نامه‌های لرزه‌ای پیشنهادی در این خصوص ارائه نشده است، در این مقاله سعی شده تا این ابهامات رفع شود. برای این منظور، مدل‌های سازه‌ای به همراه فونداسیون و محیط خاک اطراف آن، در نرم افزار ABAQUS مدل شده و با توجه به نوع خاک، تحت یک شتاب نگاشت مصنوعی منطبق بر طیف طرح آیین‌نامه 2800 قرار گرفته است. در این تحقیق از دو نوع خاک) نوع I و IV) استفاده شده است. نتایج نشان می‌دهد که محل تراز پایه شدیداً تحت تأثیر نوع خاک قرار دارد و در عین حال به تعداد ستون‌های ورودی به زیرزمین و تعداد طبقات سازه نیز وابسته است

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