طراحی پلاستیک قاب خمشی فولادی بر مبنای عملکرد و مقایسه آن با روش مبتنی بر نیرو

نوع مقاله : مقاله پژوهشی

نویسندگان

1 گروه مهندسی عمران، دانشکده مهندسی، دانشگاه کاشان

2 گروه مهندسی عمران، دانشکده مهندسی، دانشگاه کاشان، شهر کاشان، ایران

چکیده

در روش­های متداول طراحی لرزه­ای، که نیروی اعضا به حد مقاومت محدود می­گردند، عملکرد سازه به طور مستقیم در طراحی وارد نمی­شود. تنها موردی که در روش نیرو به عنوان کنترل عملکرد سازه لحاظ می­گردد، کنترل جابجایی نسبی سازه در گام نهایی طراحی است. این ضعف روش طراحی مبتنی بر نیرو، سبب شده که توجه ویژه­ای به روش­های طراحی مبتنی بر عملکرد معطوف گردد. روش طراحی پلاستیک بر اساس عملکرد یکی از روش­های طراحی عملکردی است که در آن سطح خرابی و مکانیزم خرابی مطلوب در گام­های نخستین طراحی از پیش مشخص است. انتظار می­رود که سازه طراحی شده با روش مذکور از لحاظ رفتاری انطباق بیشتری با مکانیزم مطلوب داشته باشد. در این تحقیق هر دو روش طراحی برای سازه­های چهار، هشت، دوازده و شانزده طبقه به کار گرفته شده و رفتار غیرخطی سازه­ها با تحلیل­های غیرخطی استاتیکی و دینامیکی بررسی شده‌است. تحلیل­های انجام شده نشان می­دهد سازه­های طراحی شده با روش پلاستیک بر اساس عملکرد دارای مکانیزم خرابی نزدیک­تری به آنچه در روند طراحی فرض شده‌است، می­باشند. همچنین سازه­های مذکور در تحلیل استاتیکی غیرخطی، شکل ­پذیری بیشتری از خود نشان داده اند. در این سازه­ها، توزیع مفاصل پلاستیک در تحلیل دینامیکی غیرخطی به صورت یکنواخت و فراگیر است. همچنین تمرکز خرابی شدید و مکانیزم موضعی در ستون­های سازه های طراحی شده با روش طراحی پلاستیک براساس عملکرد به دلیل مقاومت بیشتر آن­ها ایجاد نمی ­شود.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Performance Based Plastic Design of Steel Moment Frame and Comparing It with Force Based Design

نویسندگان [English]

  • Fatemeh Mousavinejad 1
  • Hassan Ostad-Hossein 2
1 Civil engineering department, faculty of engineering, University of Kashan
2 Civil engineering department, Faculty of engineering, University of Kashan, Kashan, Iran.
چکیده [English]

In conventional seismic design methods the performance of structure has not been considered in base shear estimation and structural drift, as a measure of damage, will be checked at the end of design stages. This weakness of force-based design (FBD) methods causes special attention to performance-based design. Performance-based plastic design (PBPD) is of performance-based design (PBD) in which the desired damage level and plastic mechanism of the structure are predefined at the beginning of the design procedure, to estimate internal forces. It is expected that applying PBPD ends to a structural behavior with more compliance with the desired mechanism. In this paper, the priority of PBPD over FBD has been investigated. The PBPD and FBD methods are applied to the design of four special steel moment frames of 4, 8, 12, and 16 stories. The nonlinear behavior of designed structures has been evaluated by push-over and nonlinear time history analysis. Analysis results show that the PBPD frame has mechanism mode closer to assumed mechanism mode in the design procedure. Another conclusion is that the PBPD frame mechanism in the push-over analysis is more ductile than the FBD frame. Also, it concluded that in the PBPD frame, plastic hinges are approximately distributed uniformly all over the structure. The general reason for PBPD ductility improvement, versus FBD, is the strength of columns which prevent undesirable mechanism.

کلیدواژه‌ها [English]

  • Performance based plastic design
  • force based design
  • push over analysis
  • time history analysis
  • performance objectives
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