ارزیابی ضوابط لرزه‌ای دستورالعمل DBD12 در طراحی قاب‌های خمشی بتن‌آرمه با درنظرگیری اثرات اندرکنش خاک و سازه

نوع مقاله : علمی - پژوهشی

نویسندگان

1 گروه مهندسی زلزله، دانشکده مهندسی عمران، دانشگاه سمنان، سمنان، ایران

2 دانشگاه سمنان

3 گروه عمران، دانشگاه آزاد واحد نجف آباد، اصفهان، ایران

چکیده

روش طراحی مستقیم مبتنی بر تغییرمکان به عنوان یکی از ابزارهای جدید جهت تحقق اهداف عملکردی طراح شناخته می‌شود تاکنون پژوهش‌های مختلفی پیرامون ارزیابی عملکرد سازه‌های طراحی شده به روش طراحی مستقیم مبتنی بر تغییرمکان صورت گرفته است. لیکن توجه چندانی به عملکرد سازه‌های طراحی شده به این روش با در نظر گرفتن اثرات اندرکنش خاک و سازه نشده است. در این پژوهش ارزیابی عملکرد لرزه‌ای قاب‌های خمشی بتن‌آرمه طراحی شده به روش طراحی مستقیم مبتنی بر تغییرمکان با در نظر گرفتن اثرات اندرکنش خاک و سازه در دستور کار قرار گرفته است. بدین منظور 4 قاب‌ خمشی بتن‌آرمه با ارتفاع مختلف که بر روی یک لایه خاک به عمق 20 متر قرار گرفته‌اند طبق ضوابط دستورالعمل DBD12 طراحی شده‌اند. در روند طراحی پروفیل تغییرمکان طراحی، با توجه به اثرات انعطاف‌پذیری تکیه‌گاه تصحیح شده است. در مدل‌سازی اثرات اندرکنش خاک و سازه از روش زیرسازه استفاده شده است؛ به‌‌طوری که خاک زیر سازه با استفاده از فنرها و میراگرهای جایگزین در زیر فونداسیون مدل‌سازی شده است. در مدل‌سازی رفتار غیرخطی تیرها از مدل مفصل خمیری استفاده شده است. مدل‌سازی رفتار غیرخطی ستون‌ها نیز با استفاده از مدل دوران قطری که به طور غیرمستقیم از مفاصل خمیری استفاده می‌کند، انجام شده است. به منظور بررسی رفتار قاب‌های موردنظر از تحلیل‌های تاریخچه زمانی غیرخطی با به‌کارگیری دو دسته شتاب‌نگاشت طبیعی و مصنوعی تولید شده بر اساس مبانی تبدیل موجک، استفاده شده است. نتایج حاصل از بررسی قاب‌های با پایه انعطاف‌پذیر نشان‌دهنده افزایش پاسخ تغییرمکانی قاب‌ها تا 22/8 درصد نسبت به مدل‌های با پای ثابت می‌باشد. در حالی که اثرات اندرکنش خاک و سازه تأثیر چندانی در روند تغییرمکان نسبی طبقات ایجاد نکرده است به‌گونه‌ای که در هیچ‌کدام از قاب‌ها متوسط بیشینه تغییرمکان نسبی طبقات از حدود مجاز فراتر نرفته است.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Seismic Evaluation of DBD12 Model Code Provisions in Design of RC Moment Frames Considering Soil–Structure Interaction Effects

نویسندگان [English]

  • Zohreh Jabari Salami 1
  • Mohammad Iman Khodakarami 2
  • Esmaeel Izadi Zaman Abadi 3
1 Department of Earthquake Engineering, Faculty of Civil Engineering, Semnan University, Semnan, Iran
2 Semnan University
3 Department of Civil Engineering, Najafabad Branch, Islamic Azad University, Najafabad, Iran
چکیده [English]

Today, conventional force based structural design (FBD) approach due to the weakness in controlling the expected performance level during an earthquake, do not meet the performance expectations of the designer. Direct displacement based design approach (DDBD) is recognized as one of the new main tools for satisfaction designer expected performance level. The effectiveness of DDBD approach has been evaluated in controlling the expected performance level of many structural systems so far, while the least attention has been paid to the effects of geophysical and site effect studies. In this study, seismic performance of RC frames designed with DDBD approach considering soil–structure interaction effects has been investigated. For this purpose, 4 RC frames with different heights that are placed on a 20 meters layer of soil were designed based on mentioned approaches. In the design process, the design displacement profile has been corrected according to the effect of soil-flexibility. The results of the study of frames with flexible bases show an increase in the displacement response of frames up to 8.22% compared to models with fixed bases. While the effects of soil-structure interaction did not have much effect on the story drift, so that in none of the frames the average maximum story drift did not exceed the expected performance level. In order to comprehensively investigate the soil–structure interaction effects, the performance evaluation of the RC frames in low-, medium-, and high-risk has also been examined. The results show minor changes in the maximum story drift at three different risk levels, considering soil–structure interaction effects.

کلیدواژه‌ها [English]

  • Direct displacement based design
  • Soil–structure interaction
  • Performance Based Design
  • DBD12 model code
  • time history analysis
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