ارزیابی عملکرد لرزه‌ای قاب‌های مهاربندی همگرای ویژه بزرگ مقیاس با نسبت دهانه‌های متفاوت

نوع مقاله : مقاله پژوهشی

نویسندگان

1 گروه عمران- دانشکده مهندسی- دانشگاه زنجان

2 گروه عمران، دانشکده مهندسی، دانشگاه زنجان، زنجان، ایران

چکیده

در این پژوهش عملکرد لرزه‌ای قاب‌های دارای مهاربند همگرای ویژه بزرگ مقیاس با نسبت دهانه‌های متفاوت مورد بررسی قرار می‌گیرد؛ برای این‌ منظور هشت سازه چهار و هشت طبقه با قاب مهاربندی همگرای ویژه به ‌شکل محیطی و  با پیکربندی ضربدری متعارف و ضربدری بزرگ مقیاس با نسبت دهانه‌های متفاوت، به ‌صورت سه ‌بعدی طراحی شدند، سپس یک قاب مهاربندی از آن‌ها به ‌شکل دو بعدی با در نظر گرفتن آثار مرتبه دوم بخش ثقلی حذف شده از طریق ستون متکی، در OpenSees مدل‌سازی شد. نهایتا به‌ منظور بررسی عملکرد لرزه‌ای سازه‌ها و انجام تحلیل دینامیکی فزاینده، 14 شتاب‌نگاشت حوزه دور از گسل با توجه به ویژگی‌های محل احداث بنا انتخاب شدند. بررسی نتایج تحلیل‌ها با توجه به گزارش NIST GCR 10-917-8 و دستورالعمل Hazus در شاخص حداکثر دریفت بین طبقات، مقایسه منحنی‌های شکنندگی و مقایسه پریود و وزن سازه‌ها، بیانگر این است که در قاب‌های مهاربندی همگرای ویژه در صورت مساوی بودن نسبت دهانه‌ها، مهاربند ضربدری بزرگ مقیاس عملکرد مناسب و صرفه اقتصادی دارد و در صورت متفاوت بودن نسبت دهانه‌ها، استفاده از مهاربند ضربدری بزرگ مقیاس عملکرد مناسب‌تری از مهاربند ضربدری متعارف داشته و از نظر اقتصادی هم بسیار به ‌صرفه‌تر است؛ برای نمونه در سازه‌های هشت طبقه و در نسبت دهانه 1/5 وزن نمونه دارای مهاربند ضربدری بزرگ مقیاس، حدود 20 درصد کمتر از سازه مشابه با مهاربند ضربدری متعارف است. همچنین زمان تناوب قاب‌های با مهاربند ضربدری متعارف حدود 20 تا 30 درصد از سازه‌های با مهاربند بزرگ مقیاس بیشتر است که بیانگر سختی بسیار زیاد مهاربندهای بزرگ مقیاس می‌باشد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Seismic performance assessment of special concentrically mega braced frames with different spans ratio

نویسندگان [English]

  • Ali Shadpour 1
  • Seyyed Asghar Arjmandi 2
1 Civil Engineering School, Engineering Department, University of Zanjan
2 Civil Engineering Group, Engineering Department, University of Zanjan, Zanjan, Iran.
چکیده [English]

Special concentrically braced frames achieve good seismic performance in the earthquake, these frames maintain the stability of the structure with linear behavior in weak to moderate earthquakes and with nonlinear behavior in extreme earthquakes. The design of structures is often based on linear analysis, so it is necessary to study the performance of mega-braced frames with different spans ratio by nonlinear analysis. In this study, the seismic performance of special concentrically mega-braced frames with different spans ratio is investigated. For this purpose, eight configurations of four and eight-story structures with special concentrically braced frame were designed in three dimensions, with conventional X and mega brace configurations with different spans ratio, then a braced frame of them was modeled in OpenSees in two dimensions, taking into account the second-order effects of the removed gravitational section, through a leaning column. Finally, in order to investigate the seismic performance of structures and perform incremental dynamic analysis, 14 far-field earthquakes were selected according to the characteristics of the construction site. Evaluation of analysis results according to NIST GCR 10-917-8 report and Hazus Technical Manual in maximum inter-story drift ratio, comparison of fragility curves and comparison of period and weight of structures indicates that in special concentrically mega braced frames, if the spans are equal, mega braces have a suitable and economic performance, and if the ratio of spans is different, the use of mega braces has a better performance than conventional X braces and is much more economical. For example, in eight-story structures with a span ratio of 1.5, the weight of the structure with the mega-brace is about 20% less than the similar structure with a conventional X brace. Also, the main period of frames with conventional X braces is about 20 to 30% longer than structures with mega braces, which indicates the higher stiffness of mega braces.

کلیدواژه‌ها [English]

  • Incremental dynamic analysis
  • Special concentrically braced frame
  • Mega brace
  • Fragility curve
  • Far field earthquake
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