اثر اندرکنش غیرخطی خاک-سازه بر پاسخ لرزه‌ای ساختمان‌های قاب خمشیِ ویژه‌‌ کوتاه تا بلند مرتبه فولادی

نوع مقاله : علمی - پژوهشی

نویسندگان

1 گروه مهندسی عمران، دانشگاه کاشان، ایران

2 گروه مهندسی عمران/ دانشگاه کاشان/کاشان/ایران

چکیده

رفتار غیرخطی سیستم خاک-سازه با تحمیل انعطاف‌پذیری مازاد بر سیستم و نیز اتلاف انرژی چرخه‌ای در فصل مشترک خاک و شالوده تقاضای لرزه‌ای سازه را تغییر می‌دهد. لیکن، در طراحی‌های رایج تمایلی به در نظرگرفتن اثرات غیرخطی سیستم خاک-شالوده، خصوصاً بدلیل عدم وجود تکنیکی قابل اعتماد، وجود ندارد. در این مطالعه، اثرات اندرکنش غیرخطی خاک-سازه بر پاسخ لرزه‌ای ساختمان‌های قاب خمشی ویژه فولادی مورد ارزیابی قرار می‌گیرد. ابتدا، یک مجموعه از سازه‌های متقارن فلزی با قاب خمشیِ ویژهِ 4، 8، 12 و 16 طبقه سه دهانه دارای پی سطحی واقع بر سه نوع خاک سخت، نرم وخیلی نرم طراحی می‌شوند. سپس، برای تحلیل اندرکنش از روش ساده و کاربردی فنر-میراگر معادل بر اساس مدل وینکلر استفاده می‌شود. در تحلیل تاریخچه زمانی غیرخطی سیستم خاک و سازه از بیست و یک رکورد زلزله در سطوح خطر مختلف استفاده می‌شود. نتایج تحلیل نشان می‌دهد که اندرکنش دینامیکی خاک-سازه بخصوص با نرم‌تر شدن خاک، افزایش سطح خطر زلزله و افزایش تعداد طبقات ساختمان می‌تواند نقشی اساسی در رفتار لرزه‌ای قاب‌های خمشی ساختمانی فولادی شامل افزایش پریود سیستم، افزایش قابل توجه در تغییر مکان جانبی و دریفت طبقات، افزایش برش درون طبقه و برش پایه و به دنبال آن کاهش سطح عملکرد سازه داشته باشد. بر اساس نتایج بدست آمده چنانچه اندرکنش دینامیکی خاک و سازه بطور مناسبی در تحلیل و طراحی لحاظ نشود دقت ارزیابی ایمنی سازه‌ در مواجه با زلزله نمی‌تواند مورد اعتماد باشد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Influence of nonlinear SSI on the seismic response of low-to-mid-rise steel moment resisting frame buildings

نویسندگان [English]

  • Mohammad Arbabi 1
  • Hossein Tahghighi 2
1 Civil Eng dept., University of Kashan, Iran
2 Civil Eng department, University of Kashan
چکیده [English]

The nonlinear behavior of a soil–foundation interface due to mobilization of the ultimate capacity and the consequent energy dissipation may be utilized to alter seismic demands of a structure. However, current design practice does not account for the nonlinear behavior of soil–foundation interface primarily due to the absence of reliable nonlinear soil–structure interaction (SSI) modeling techniques. The objective of this study is to simulate the performance of multi-story building-foundation systems through a Winkler-based approach. Opensees finite element framework is employed for simulation. Four typical 4, 8, 12 and 16-story steel moment resisting frame (MRF) buildings on three hypothetically soft, medium and hard soil sites with shear wave velocities less than 600m/s subjected to actual ground motion records of varied hazard levels are modeled with and without SSI. It is observed that the performance level of models supported by flexible foundation, particularly in an intense earthquake event, may alter significantly in comparison to fixed-base structures. Moreover, for MRFs on soft soil, the nonlinear foundation is found to have a significant effect on the force and displacement demands. This is indicating the necessity for consideration of flexible foundation behavior in the modern design codes in order to accomplish an economic yet safe structural design.

کلیدواژه‌ها [English]

  • Earthquake response
  • Soil–structure interaction
  • Steel MRF
  • Nonlinear behaviour
  • Hazard levels
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