توسعه المان فیبری بتن مسلح مبتنی بر میدان تنش محلی و برهم‌کنش بتن و آرماتور

نوع مقاله : مقاله پژوهشی

نویسندگان

دانشگاه فردوسی مشهد، دانشکده مهندسی، گروه عمران, ایران

چکیده

در این پژوهش، مدلی تحلیلی جهت توسعه روش فیبری مبتنی بر تئوری میدان تنش محلی ارائه می‌شود. در این راستا، مبانی فرمول‌بندی مدل فیبری به همراه رویکرد لاگرانژی در کرنش‌های بزرگ ارائه شده و معادلات حاکم بر المان قابی پیشنهادی در فرم تضعیف شده اجزا محدودی بازنویسی می‌گردد. همچنین قید پیوستگی کامل بین فیبرهای بتنی و میلگردها برداشته شده و معادلات حاکم بر المان قابی بتن مسلح برای میلگردهای هر لایه به صورت مجزا توسعه می‌یابد. بازنویسی فرمولی این المان بر مبنای تئوری تیر تیموشنکو به همراه اثرات اندرکنشی محوری، خمشی و برشی در دامنه هر المان بتن مسلح انجام می‌گیرد. قابل ذکر است، در فرآیند پیاده‌سازی روش، برهم‌نهی کنش‌های محوری و خمشی با کنش‌های برشی همراه با وارد شدن مستقیم عبارت‌های مربوطه در ماتریس سختی سویی مقطع المان فیبری در نظر گرفته می‌شود. بر همین اساس، با استفاده از فاکتور اصلاح برشی مبتنی بر تئوری میدان تنش محلی در توابع هرمیتی، حل غیرخطی مستقیم تکراری برای هر گام بارگذاری انجام می‌گیرد. صحت‌سنجی روش تحلیلی ارائه شده با مطالعات آزمایشگاهی موجود بر روی اعضای بتنی مسلح مورد آزمون و ارزیابی قرار گرفته که نتایج حاصل از تحلیل نشان از تقریب نسبتاً مناسب و همگرایی قابل قبول در مسائل را دارد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Proposing an RC Fiber Frame Element Based on Local Stress Field Theory and Bar-Concrete Interaction

نویسندگان [English]

  • Behrooz Yousefi
  • Mohammadreza Esfahani
  • Mohammadreza Tavakkolizadeh
Department of Civil Engineering, Ferdowsi Unversity of Mashhad
چکیده [English]

This research presents an analytical model for developing a fiber frame element based on local stress field theory. The proposed formulation is developed through the Lagrangian kinematics assumption to derive the weak form of the equations in large strain conditions. In this regard, the effect of bond-slip has been considered by removing the perfect bond assumption. The governing equations for each element are developed by the directional stiffness matrix in weak form. The extracted formula is based on Timoshenko's beam theory, with axial, bending, and shear interaction effects in the domain of each element. The components of the stiffness matrix are defined through directional derivatives of the semi-linear form of the equations. Moreover, the suggested approach evolves from cubic Hermitian polynomials and the local stress field theory. The validation of the analytical method is provided by the available experimental tests. The implemented code could cover the overall behavior of reinforced concrete members, as well as, the maximum crack width, slip profile, and crack growth. The results show that such a modeling method is capable of simulating RC members.

کلیدواژه‌ها [English]

  • Fiber Frame Element
  • Smeared crack approach
  • Timoshenko's Theory
  • Bond-Slip Effect
  • Lagrangian Approach
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