تحلیل هزینه‌ی چرخه‌ی عمر ترک ناشی از خوردگی یکنواخت کلریدی در تیر بتن آرمه

نوع مقاله : مقاله پژوهشی

نویسندگان

دانشکده مهندسی عمران، دانشگاه صنعتی نوشیروانی بابل، بابل، ایران.

چکیده

خوردگی آرماتور، فرآیندی پیچیده و از مهم‌ترین عوامل شکست سازه‌های بتن مسلح است که باعث کاهش مقاومت و خدمت‌پذیری سازه می‌گردد که جلوگیری از این اثرات منفی، مستلزم صرف هزینه‌های گزافی است. به همین دلیل نیاز است که این فرآیند با استفاده از تحلیل‌های احتمالاتی و آنالیز قابلیت اعتماد با در نظر گرفتن عدم قطعیت‌ها در فاز خوردگی، مدل‌سازی شود. همچنین با در نظر گرفتن روش‌های مختلف نگهداری و آنالیز چرخه عمر، می‌توان هزینه تعمیر و نگهداری ناشی از خوردگی را به حداقل رساند. از اثرات خوردگی بر عملکرد سازه، ترک ناشی از گسترش محصولات خوردگی است. عرض ترک یک پارامتر مهم برای طراحی و ارزیابی عملکرد سازه‌های بتنی است. بنابراین در این مقاله ابتدا مدلی تحلیلی برای محاسبه عرض ترک ناشی از خوردگی ارائه گردید. پیش‌بینی ترک در مراحل مختلف در طول انتشار ترک از سطح میلگرد تا سطح پوشش بتن مورد بررسی قرار می‌گیرد. از جمله ویژگی بارز این مدل این است که به طور مستقیم به فاکتورهای بحرانی موثر بر عرض ترک مربوط می‌شود.‌ در ادامه ضمن در نظر گرفتن عرض ترک به عنوان متغیر تصادفی در محاسبه احتمال ترک خوردگی سازه‌های بتنی که  بر اساس فرآیند تصادفی گاما صورت می‌پذیرد، به بررسی هزینه‌های چرخه عمر و تعیین بازه بهینه تعمیر از طریق فرآیند تجدید، پرداخته می‌شود. همچنین اثر پارامترهای سازه‌ای شامل قطر میلگرد و نرخ خوردگی، بر احتمال گسیختگی سازه و هزینه‌های ناشی از خرابی در چرخه عمر بررسی می‌شود. نتایج حاکی از آن است که از بین این پارامترها، نرخ خوردگی بیشترین تاثیر را بر عرض ترک و هزینه چرخه عمر دارد.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Life-cycle cost analysis of cracking in a reinforced concrete beam under uniform chloride corrosion

نویسندگان [English]

  • Masoumeh Taghipour
  • Mehdi Dehestani
Faculty of Civil Engineering, Babol Noshirvani University of Technology
چکیده [English]

Corrosion of rebar is one of the major problems in reinforced concrete structures under a corrosive environment which causes serious damage to the structures. Corrosion of rebar is a complex process and one of the important factors of failure of reinforced concrete structures which reduces the strength and serviceability of the structures thus avoiding these adverse effects requiring a high cost. For this reason, this process needs to be modeled using probabilistic analysis and reliability analysis with uncertainties in the corrosion phase. Considering the different maintenance strategies and life cycle analysis methods, the cost of maintenance and repair can be delayed. One of the corrosion effects on structure performance is crack on the concrete surface due to the expansion of the corrosion product. The crack width is an important parameter for designing and evaluating the performance of concrete structures. Therefore, this paper presents an analytical model to calculate the crack width due to corrosion. Crack evolution in the concrete cover due to expansive corrosion products is investigated at different stages during crack propagation across the cover, from the reinforcing bar-concrete interface to the concrete. A merit of this model is that it is directly related to the factors that affect the corrosion-induced cracking process. Then, the predicted crack width is chosen as a stochastic variable and the probability of failure in concrete structures is calculated by using a stochastic deterioration model and the gamma process. The calculated probability is then used to calculate the life cycle cost and determine the optimal repair time by using the renewal process. The effect of structural parameters on the probability of failure is also investigated. The results show that the corrosion rate is one of the most important factors affecting the crack width, the probability of failure, and life cycle cost.

کلیدواژه‌ها [English]

  • Corrosion of Reinforcement
  • Reliability
  • Life Cycle
  • Probability of Failure
  • Corrosion Rate

مراجع

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نشریه مهندسی عمران امیرکبیر
دوره 53، شماره 4
تیر 1400
صفحه 1491-1506

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