طراحی لرزه ای بهینه سازه های با میراگر پسماندی با در نظر گرفتن انعطاف پذیری خاک

نوع مقاله : علمی - پژوهشی

نویسنده

دانشکده مهندسی عمران، دانشگاه مازندران، بابلسر، ایران

چکیده

استفاده گسترده‌ی سیستم‌های اتلاف انرژی موجب شده است تا محققان به دنبال بهینه‌سازی مشخصه‌های مکانیکی این سیستم‌ها جهت بهبود عملکرد لرزه‌ای سازه‌ها باشند. تا کنون تحقیقات قابل توجهی بر روی بهینه سازی سازهای پای ثابت دارای میراگرهای غیرفعال انجام شده است. از طرفی مطالعات اخیر نشان داده است که اثر اندرکنش-خاک سازه می‌تواند به طور قابل‌توجهی الگوی بار لرزه‌ای بهینه سازه‌های ارتجاعی و خصوصا غیر‌ارتجاعی را تحت تاثیر قرار دهد. دراین تحقیقات الگوریتمهای بهینه‌سازی جدیدی برای طراحی لرزه‌ای بهینه سازه‌های برشی با در نظرگرفتن اثر انعطاف‌پذیری خاک (اندرکنش خاک-سازه) ارائه شد. هرچند که مطالعات بسیار محدودی در رابطه با بهینه سازی لرزه‌ای اینگونه ساز‌ها با حضور میراگرها مطرح شده است. در این مطالعه، با ارائه‌ی یک الگوریتم پیشنهادی مبتنی بر توزیع خسارت یکنواخت بر روی سازه‌های برشی معادل‌، اثر اندرکنش خاک-سازه بر توزیع بهینه میراگرهای پسماندی مورد مطالعه‌ی پارمتریک قرار می‌گیرد. بدین منظور ساز‌های برشی معادل با سازه‌‌های فولادی واقعی دارای میراگر‌های پسماندی واقع بر بستر انعطاف‌پذیر تحت اثر 15 شتابنگاشت زمین‌لرزه‌ی دور از گسل که بدون پالس می‌باشند بهینه شده و اثر پامتر‌‌های موثر اندرکنشی در پاسخ بهینه مورد بررسی قرار می‌گیرد. نتایج این مطالعه حاکی از آنست که استفاده از الگوریتم پیشنهادی برای دستیابی به توزیع بهینه میراگر‌های پسماندی با احتساب اثر اندرکنش خاک-سازه، امکان آن را فراهم می‌آورد که با توزیع مناسب میراگرهای پسماندی، عملکرد لرزه ای سازه اولیه تا حد قابل توجهی افزایش یابد. همچنین نتیجه گرفته شد که اثر پارامترهای کلیدی اندرکنشی مانند فرکانس بی‌بعد و نسبت لاغری در نحوه‌ی توزیع الگوی بهینه کاملا قابل ملاحظه است، به نحوی که افزایش اثر اندرکنش-خاک سازه موجب افزایش بار لرزه‌ای در پای سازه و خصوصا در طبقه‌ی بام می‌شود که می‌تواند ناشی از افزایش انعطاف‌پذیری سیستم خاک-سازه نسبت به حالت پای ثابت و اثر قابل توجه مودهای بالاتر باشد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Optimum Seismic Design of Structures with Hysteretic Damper Considering Soil Flexibility

نویسنده [English]

  • Behnoud Ganjavi
Department of Civil Engineering, University of Mazandaran, Babolsar, Iran
چکیده [English]

The widespread use of energy dissipation systems has led researchers to investigate the optimal mechanical properties of these systems for improving the seismic performance of a structure with the installation of such devices. So far, considerable researches have been conducted on optimum seismic design of fixed-base systems with passive dampers. On the other hand, recent studies have shown that effect of soil-structure interaction (SSI) can have remarkable effects on optimum seismic loading patterns of structures in both elastic and inelastic states. In these investigations, several new optimization algorithms were proposed for optimum seismic design of buildings considering soil-structure interaction effects. However, very rarer optimization studies have performed on soil-structures systems with dampers. In this paper, a new optimization algorithm based on uniform damage distribution of equivalent shear building model considering soil-structure interaction effect is developed. To this end, shear buildings models with hysteretic dampers located on flexible base soil are optimized under 16 far-fault earthquake ground motions without pulse, and the effect of key soil-structure interaction parameters on optimum response is investigated. Results of this study indicate that using proposed optimization algorithm for soil-structure systems with hysteretic dampers to achieve optimum distribution of dampers will lead to significant improvement of the seismic performance of the primary structure. In addition, it was concluded that the soil-structure key parameters such as dimensionless frequency and structural slenderness ratio can significantly affect the optimum load patterns such that increasing SSI effect will lead to increasing seismic load on base and top of the structure compared to the fixed-base systems. This can be attributed to the flexibility and higher modes effect of soil-structure systems when compared to the corresponding fixed-base system.

کلیدواژه‌ها [English]

  • Hysteretic damper
  • Optimum design
  • Soil-structure interaction
  • Inelastic inter-story drift
  • Seismic load pattern
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