تحلیل عملکرد مدل های پیوستگی-لغزش بین بتن و FRP در مدل سازی اجزاءمحدود تیر بتن آرمه تقویت شده با ورق FRP

نوع مقاله : علمی - پژوهشی

نویسندگان

1 دانشکده مهندسی عمران دانشگاه صنعتی نوشیروانی بابل

2 گروه سازه و زلزله، دانشکده مهندسی عمران، دانشگاه صنعتی نوشیروانی بابل، بابل، ایران

چکیده

هدف این پژوهش آنالیز عملکرد مدل‌های مختلف پیوستگی-لغزش در پیش‌بینی رفتار تیر بتنی تقویت شده توسط ورق FRP می‌باشد. به منظور درک بهتر مکانیزم جداشدگی در تیرهای بتنی تقویت‌شده با ورق FRP، از مدل اجزاءمحدود جامعی بر پایه‌ی روش خرابی-پلاستیسیته‌ی بتن استفاده‌شده‌است. در این مدل‌سازی از المان چسبنده برای مدل‌سازی رفتارپیوستگی بین بتن و میلگرد و بتن و ورق FRP استفاده‌شده‌است. از نتایج چندین نمونه‌ی آزمایشگاهی تیر بتنی تقویت‌شده توسط ورق FRP جهت صحت‌سنجی استفاده شده‌است. با مقایسه‌ی نتایج به‌دست‌آمده از مدل اجزاء‌محدود با نتایج آزمایشگاهی توانایی بالای مدل انتخاب شده در پیش-بینی رفتار تیر به اثبات‌ رسیده‌است. توزیع دندانه‌ای کرنش‌ها در صفحات FRP ناشی از وقوع ترک‌ها در بتن می‌باشد. با ادامه بارگذاری تعداد مقاطع ترک‌خورده و بازشدگی ترک‌ها افزایش یافته و حالت دندانه‌ای منحنی‌های کرنش تشدید می‌شود. از طرفی تسلیم آرماتورهای کششی ، سبب افزایش ناگهانی کرنش در ورقFRP می‌شود. مقادیر تنش سطحی بین ورق FRP و بتن در گام‌های نهایی بارگذاری به دلیل گسترش ترک‌ها و آزاد شدن تنش‌ها در محل ترک، نوسان زیادی نشان می‌دهد. بیش‌ترین مقادیر لغزش بین بتن و FRP در نزدیکی نقاط بارگذاری‌شده روی تیر که نیروی برشی و ممان خمشی در حالت بیشینه بوده رخ می‌دهد. نتایج نیرو-تغییرمکان به‌دست‌آمده نشان‌دادند که دو مدل لو-دوخطی و لو-ساده شده در مدل‌سازی‌پیوستگی بین بتن و ورق FRP بهترین عملکرد را داشته و در محاسبه‌‌ی مقادیر بار گسیختگی به‌طور میانگین به ترتیب 3.8%و 6.1% خطا نسبت به نتایج آزمایشگاهی داشته-اند.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Performance analysis of various bond-slip models in finite element modelling of reinforced concrete beams strengthened with FRP sheets

نویسندگان [English]

  • Arya SadeghAmal Nikraftar 1
  • Mehdi Dehestani 2
1 Babol Noshirvani University of Technology
2 Faculty of Civil Engineering, Babol Noshirvani University of Technology, Babol, Iran
چکیده [English]

The purpose of this study is to analyze the performance of various bond-slip models in modelling of reinforced concrete beams strengthened with FRP sheets. A comprehensive finite element model based on the concrete damage-plasticity behavior has been constructed. The cohesive element is used to model the bond-slip behavior and existing experimental results were used for verification. By comparing the results of the finite element model with the experimental results, the capability of the selected model in predicting beam behavior has been proven. The indent distribution of strains in FRP plates was due to the occurrence of cracks in concrete. With an increase in the loading, both the crack opening and the number of cracked sections in the beam are increased and the indentation state of the strain curves is intensified. On the other hand, the yielding of tensile rebars increases the strain in the FRP sheet. The interfacial shear stress values between FRP sheets and concrete shows high fluctuation at the final stages of loading due to the development of cracks and release of stresses at the crack tip. Maximum slip values between concrete and FRP surface occur near the loading points in which bending moment and shear force are maximum. The obtained load-displacement results showed that Lu-Bilinear and Lu-Simplified models have the best performance in modeling the bond between concrete and FRP sheets and in predicting the failure load of beams, they had On average 3.8% and 6.1% error with respect to experimental results, respectively.

کلیدواژه‌ها [English]

  • Finite element
  • FRP Sheet
  • Bond-Slip Model
  • Cohesive Element
  • Concrete Damage-Plasticity

مراجع

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سابقه مقاله

  • تاریخ دریافت: 23 فروردین 1399
  • تاریخ بازنگری: 07 مهر 1400
  • تاریخ پذیرش: 04 آذر 1400

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