مدل عمر تیر بتنی بر مبنای مقاومت برشی تحت اثر حالت‌های مختلف نفوذ یون کلراید

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشکده صنعت و معدن، دانشگاه یاسوج، چرام، ایران

2 گروه مهندسی عمران، دانشگاه صنعتی بیرجند، بیرجند، ایران

چکیده

سازه‌های بتنی در طی عمر خود تحت اثر عوامل محیطی دچار کاهش مقاومت و در نهایت زوال زود هنگام می‌شوند. خوردگی میلگردها به عنوان یکی از مهم‌ترین عوامل تاثیرگذار در کاهش عملکرد سازه‌های بتنی شناخته شده است. ارزیابی وضعیت کنونی و همچنین پیش‌بینی عمر مفید باقی‌مانده سازه‌ها برای ارائه برنامه‌های تعمیر و نگهداری از اهمیت زیادی برخوردار است. در این تحقیق با در نظر گرفتن تابع شرایط حدی نهایی مقاومت برشی تیر بتن مسلح، مدل عمر تحت سناریوهای مختلف نفوذ یون کلراید محاسبه گردیده است. کاهش سطح مقطع میلگردهای طولی و عرضی، کاهش سطح مقطع تیر بتنی که به عنوان اثرات جانبی خوردگی میلگرد شناخته می‌شوند در ارزیابی مدل عمر در نظر گرفته شده‌اند. خواص تصادفی پارامترهای مؤثر در مقاومت برشی و همچنین نفوذ یون کلراید برای ارزیابی احتمالاتی مدل عمر نیز در نظر گرفته شده است. در زمان‌های بعد از شروع خوردگی، بر اساس کاهش‌های صورت گرفته در پارامترهای موثر بر مقاومت برشی، با استفاده از روش نمونه‌برداری مونت‌کارلو از هر پارامتر بر اساس خواص تصادفی آن تعداد صد هزار مقدار برای هر متغیر تولید شد. با استفاده از مقادیر تولید شده، مقاومت برشی در هر زمان محاسبه گردیده است. نتایج نشان می‌دهد که در نظر گرفتن اثر پوسته شدن بتن موجب تفاوت زیاد در مقادیر پیش‌بینی شده برای مقاومت برشی تیر بتنی می‌شود به طوری که در حالت بحرانی در نظر گرفتن اثرات پوسته شدن بتن موجب کاهش 20 درصدی مقاومت برشی می‌شود و ارزیابی واقع بینانه‌تری از عمر باقی‌مانده سازه به دست خواهد آمد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Concrete Beam Life Model Based on Shear Strength Degradation Under Different States of Chloride Ion Ingress

نویسندگان [English]

  • Seyed Abbas Hosseini 1
  • Mansour Bagheri 2
1 Faculty of Technology and Mining, Yasouj University, Yasouj
2 Department of Civil Engineering, Birjand University of Technology
چکیده [English]

Concrete structures undergo a reduction in strength and ultimately premature deterioration during their life due to environmental factors. Corrosion of reinforcement is known as one of the most important factors in reducing the performance of concrete structures. Assessing the current condition as well as predicting the remaining useful life of structures is very important for providing maintenance plans. In this research, considering the limit-state function of the shear strength of reinforced concrete beams, the life model is calculated under different scenarios of chloride ion penetration. Reduction of the cross-section of longitudinal and transverse rebars, reduction of the cross-section of the concrete beam, and reduction of mechanical properties of concrete and rebar, which are known as side effects of rebar corrosion, have been considered in evaluating the life model. Stochastic properties of effective parameters in shear strength, as well as chloride ions, are also considered for the probabilistic evaluation of the life model. The Monte Carlo sampling method was used to generate the input values of the models. The results show that considering the effect of concrete scaling causes a large difference in the predicted values for the shear strength of concrete beams, so in the critical case, considering the effects of concrete scaling reduces the shear strength by 20% and a more realistic estimate of the remaining life of the structure will be obtained.

کلیدواژه‌ها [English]

  • Life model
  • Reinforcement corrosion
  • Shear failure
  • Concrete beam
  • Chloride ingress
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