ارزیابی جامع شاخص‌های خسارت قاب‌های خمشی بتن‌آرمه در روش‌های طراحی‌ لرزه‌ای متداول و نوین

نوع مقاله : Articles

نویسندگان

1 گروه مهندسی عمران- زلزله، مؤسسه غیرانتفاعی دانش‌پژوهان پیشرو، اصفهان

2 دانشکده مهندسی عمران، واحد نجف آباد، دانشگاه آزاد اسلامی، نجف آباد

چکیده

عدم رضایت در کنترل ایمنی و پایایی سازه­های طراحی شده به روش­های متداول، دلیل گرایش محققین به روش­های طراحی بر اساس عملکرد است. طراحی مستقیم مبتنی بر تغییر مکان یکی از محبوب­ترین این روش­هاست. تحقیقات گذشته در بررسی شاخص­های کلی سازه­ها تا حد زیادی کارایی این روش را تأیید می­کنند. لیکن بررسی جامع­تر آن مستلزم برآورد خسارت المان­ها و وارد شدن به حیطه ارزیابی­های احتمالاتی می­باشد. هدف از این مطالعه بررسی روش طراحی مستقیم از چهار دیدگاه مختلف شامل تغییر مکان جانبی نسبی، خسارت­های موضعی، ارزیابی احتمالاتی و هزینه ساخت می­باشد. به‌منظور بررسی پاسخ تغییر مکانی و خسارت­های موضعی سازه­ها از چهار قاب خمشی بتن­آرمه با ارتفاع 3، 5، 7 و 11 طبقه استفاده شده است. نتایج نشان­دهنده‌‎ی تأمین سطح عملکرد انتخابی در خصوص پاسخ­های تغییر مکانی و عدم تجاوز دوران مفاصل پلاستیک از سطح ایمنی جانی در روش طراحی مستقیم برخلاف روش نیرویی می­باشند. نتایج ارزیابی احتمالاتی در پنج حالت خرابی در دو دسته از قاب­ها نشان‌دهنده‌ی احتمال خرابی کمتر در روش طراحی مستقیم برخلاف روش نیرویی می­باشد. ضمن اینکه تحلیل هزینه نشان­دهنده‌ی افزایش آرماتور مصرفی بین 6/6 تا 11/52 درصد و افزایش بتن مصرفی تا 4/3 درصد در روش طراحی مستقیم نسبت به روش نیرویی می­باشد.

کلیدواژه‌ها


عنوان مقاله [English]

Comprehensive Assessment of Damage Indices of RC Frames in Conventional and Novel Seismic Design Approaches

نویسندگان [English]

  • Zohreh Jabari Salmi 1
  • Esmaeel Izadi Zamanabadi 2
1 Daneshpajoohan Pishro Institute of Higher Education, Isfahan, Iran
2 Faculty of Civil Engineering, Najafabad Branch, Islamic Azad University, Najafabad, Iran
چکیده [English]

Experience of the past earthquakes reveals that conventional force based design (FBD) approach, only provide minimum requirement for life safety performance level of structures. While these methods do not capable to control structural seismic damages. In recent years, displacement based design approaches have been proposed as the main tools of performance based design. Direct displacement based design (DDBD) is recognized as one of the most efficient methods. In this method, an inelastic multi degree of freedom structure is substituted with an equivalent elastic single degree of freedom. The substitute structure is designed for a target displacement and an equivalent viscous damping using elastic displacement response spectrum. The effectiveness of this method has been examined in controlling the overall seismic demands of many structural systems, while the least attention has been paid to the effects of local damages.
In this study, seismic performance of a set of RC frames designed with DDBD and FBD approach (based on Iranian seismic code) has been investigated and compared with a focus on local damages. DDBD and FBD method was applied to four reinforced concrete regular frames of 3, 5, 7 and 11 story and performance of the methods was compared using inelastic time history analysis (ITHA). In the seismic assessment process, in addition to general structural responses, the distribution of local damages has also been investigated. The Park–Ang damage index was selected as the seismic damage index and probability of exceedance of the damage limit state was compared using fragility curves developed for five damage levels.
Results show that very good control of displacement and inter-story drift of RC frames designed with DDBD approach. Evaluation of the plastic hinge rotation shows, DDBD unlike FBD approach has been satisfied expected performance level. Furthermore DDBD approach provided more control on selected seismic damage index and distribution of damage index at height of structures is more uniform than FBD approach. The cost analysis shows that consumable rebar is increased 6.6%-52.11% and consumable concrete is up to 3.4% in DDBD approach compared with FBD approach, which is more exponential in frames with higher elevations.

کلیدواژه‌ها [English]

  • Direct Displacement Based Design
  • Seismic Damage Index
  • Local Damage
  • Fragility Curve
  • DBD12 Model Code
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