مهندسی سازه و ساخت

مهندسی سازه و ساخت

تاثیر زاویه اعمال شتاب نگاشت‌های دو جهته بر پارامتر‌های نیاز لرزه‌ای سیستم‌های مهاربندی واگرا

نوع مقاله : علمی - پژوهشی

نویسندگان
1 کارشناس ارشد مهندسی سازه، دانشکده مهندسی عمران، دانشگاه صنعتی نوشیروانی بابل، بابل، ایران
2 دانشیار، دانشکده مهندسی عمران، دانشگاه صنعتی نوشیروانی بابل، بابل، ایران
3 کارشناس ارشد مهندسی زلزله، دانشکده مهندسی عمران، دانشگاه صنعتی نوشیروانی بابل، بابل، ایران
چکیده
اثر زاویه اعمال شتاب نگاشت‌ها به سازه‌ها بر روی خسارت وارده به سازه و نیاز لرزه‌ای در زلزله‌های دور از گسل از چند دهه پیش مورد توجه محققین بوده است. اما این موضوع در زلزله‌های حوزه نزدیک اخیرا بیشتر مورد توجه محققین و آیین نامه‌های طراحی قرار گرفته است. این موضوع به علت حرکت‌های پالسی شکل زمین ناشی از پدیده جهت پذیری پیش رونده در زلزله‌های نزدیک گسل می‌باشد، که تاثیر زاویه اعمال شتاب ‌نگاشت‌ها را بر روی نیاز لرزه‌ای بیشتر می‌کند. با توجه به اهمیت این موضوع در سالیان گذشته تحقیقات متعددی جهت تکمیل ضوابط طراحی در نواحی نزدیک گسل انجام شده است. به عنوان مثال آیین نامه بارگذاری آمریکا برای طراحی با استفاده از تحلیل تاریخچه زمانی غیرخطی، توصیه می‌کند که نگاشت‌های نزدیک گسل انتخابی ابتدا در جهت موازی و عمود بر گسل به محور‌های اصلی سازه اعمال شوند. هدف از این تحقیق بررسی کارایی روش پیشنهادی جهت طراحی سازه‌ها در نزدیک گسل می‌باشد. بدین منظور با مدل‌سازی غیرخطی سازه‌ای با سیستم مهاربندی واگرا و اعمال شتاب نگاشت‌های نزدیک گسل به سازه با زوایای برخورد متفاوت، پاسخ‌های نیاز لرزه‌ای مورد ارزیابی قرار گرفت. نتایج این تحقیق نشان می‌دهد که نه تنها جهت پاسخ بیشینه، با تغییر شتاب نگاشت و نوع پارامتر نیاز لرزه‌ای تغییر پیدا می‌کند، بلکه این جهت در طبقات مختلف مدل مورد نظر نیز متغیر است. اما پاسخ سازه به جهت عمود بر گسل تخمین قابل قبولی از بیشینه پاسخ ارائه می‌دهد که برای اهداف طراحی مناسب است. به طوریکه تقریباً در 70% مواقع، نسبت پاسخ جهت عمود بر گسل به پاسخ بیشینه، بیش از 75/0 می‌باشد.
کلیدواژه‌ها

موضوعات


عنوان مقاله English

Influence of Angle of Incidence on Seismic Demands of Eccentric Braced Frames Subjected to Near-Fault Ground Motions

نویسندگان English

mohammad amin safari 1
Horr Khosravi 2
sara farzaneh 3
1 MSc in Structural Engineering, Department of Civil Engineering, Babol Noshirvani University of Technology, Babol, Iran
2 Associate professor, Department of Civil Engineering, Babol Noshirvani University of Technology, Babol, Iran
3 MSc in Earthquake Engineering, Department of Civil Engineering, Babol Noshirvani University of Technology, Babol, Iran
چکیده English

The effect of the angle of incidence on the structural damage and the seismic demand in far-fault earthquakes has been taken into consideration by many researchers for several decades. However, this issue has recently received more attention from researchers and design codes for near-fault earthquakes. This issue is due to the pulse-type motion caused by forward directivity phenomena in near-fault earthquakes which increases the influence of the angle of incidence on the seismic demand. Due to the importance of the issue, several researches have been conducted in the past years to improve the design criteria for near-fault regions. For example, for Nonlinear Time History Analysis (NTHA), ASCE/SEI 7-16 design code recommended that the selected near-fault ground motions should be first rotated in the fault-normal/fault-parallel directions and then applied to the main axes of the structure. This paper aims to investigate the accuracy and efficiency of the proposed method for design of structures in near-fault regions. For this purpose, using nonlinear macro modeling of an Eccentrically Braced Frame (EBF) and applying near-fault ground motions with different angle of incidence, the seismic demands of structures were evaluated. The analysis results show that not only the direction of maximum response changes with the change of near-fault ground motions and the types of seismic demand parameters, but also it varies in different stories of a building. Nevertheless, the fault-normal response usually provides an acceptable estimate of the maximum response, which is suitable for design purposes. So that in almost 70% of the cases, the ratio of the fault-normal response to the maximum response is more than 0.75.

کلیدواژه‌ها English

Near-fault ground-motion
Angle of incidence
Eccentric braced frame
Response history analysis
Engineering demand parameters
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دوره 11، شماره 2 - شماره پیاپی 79
اردیبهشت 1403
صفحه 204-228

  • تاریخ دریافت 03 اردیبهشت 1402
  • تاریخ بازنگری 10 تیر 1402
  • تاریخ پذیرش 24 تیر 1402