دانلود مقاله مدل ارزیابی خرابی برای منطقه پاشش سازه های بتنی دریایی
خلاصه
1. معرفی
2. روش شناسی
3. نتایج و بحث
4. مطالعه موردی
5. نتیجه گیری ها
بیانیه مشارکت نویسندگی اعتباری
اعلامیه منافع رقابتی
سپاسگزاریها
در دسترس بودن داده ها
منابع
Abstract
1. Introduction
2. Methodology
3. Results and discussion
4. Case study
5. Conclusions
CRediT authorship contribution Statement
Declaration of Competing Interest
Acknowledgements
Data Availability
References
چکیده
بتن در معرض منطقه پاشش در سازه‌های بتنی نیمه غوطه‌ور به دلایلی مانند چرخه‌های مرطوب و خشک کردن، تأثیر مواد موجود در آب، تخریب زیستی، حملات کلرید و سولفات به سرعت تخریب می‌شود. سیستم‌های ارزیابی وضعیت و رتبه‌بندی موجود به رابطه متقابل بین ویژگی‌های عملکردی مختلف مناطق پاشش پایبند نیستند و این مدل‌ها به شدت تابع عملکرد ارزیاب هستند. اهداف این مطالعه ارزیابی اثربخشی پارامترهایی است که سازه‌های بتنی دریایی را تخریب می‌کنند و یک مدل جدید برای پیش‌بینی میزان زوال ناحیه پاشش در سازه‌های بتنی دریایی ایجاد می‌کند. فرآیند تحلیل سلسله مراتبی فازی (FAHP) برای توسعه مدل برای پیش‌بینی میزان زوال استفاده شد. در اینجا، عوامل محلی تحت پنج پارامتر اصلی به عنوان بازرسی بصری، کیفیت آب، عوامل اتفاقی، آزمایش‌های غیر مخرب (NDTs) و جزئیات ترک گروه‌بندی شدند. داده‌های مربوط به 15 سازه با بازرسی بصری، آزمایش‌های آزمایشگاهی و صحرایی برای اعتبارسنجی مدل پیشنهادی جمع‌آوری شد. ویژگی های کیفیت آب بالاترین اولویت را برای زوال ناحیه اسلش سازه های بتنی دریایی به دست آورد. علاوه بر این، مقادیر عددی به این مدل رتبه بندی اختصاص داده شد تا از ابهام و مبهم بودن توصیفگرهای زبانی در سیستم های رتبه بندی موجود جلوگیری شود. در نهایت می‌توان از مدل توسعه‌یافته در این تحقیق برای ارزیابی درصد فرسودگی ناحیه پاشش در سازه‌ها استفاده کرد و با توجه به آن، عملیات مقاوم‌سازی و تعمیر مناسب را انجام داد.
Abstract
Concrete exposed to splash zone in partially submerged concrete structures deteriorates rapidly due to reasons such as wetting-drying cycles, the impact of waterborne materials, bio-deterioration, chloride and sulphate attacks. Existing condition assessment and rating systems do not adhere to the interrelation between different performance attributes of splash zones and these models are extremely subjective to the performance of the evaluator. The objectives of this study are to evaluate the effectiveness of parameters that deteriorate marine concrete structures and to develop a new model to predict the rate of deterioration of splash zone in marine concrete structures. The fuzzy Analytical Hierarchy Process (FAHP) was used to develop the model to predict the rate of deterioration. Here, local factors were grouped under five primary parameters as visual inspection, water quality, casual factors, Non-Destructive Tests (NDTs) and crack details. Data relevant to 15 structures were gathered by visual inspection, laboratory and field experiments to validate the proposed model. Attributes of water quality achieved the highest priority for the deterioration of the slash zone of marine concrete structures. Further, numerical values were assigned to this rating model to avoid ambiguity and vagueness of linguistic descriptors in existing rating systems. Finally, the model developed in this study can be used to evaluate the deterioration percentage of the splash zone in structures and according to that appropriate retrofitting and repair work can be done.
Introduction
At the present, reinforced concrete has been widely used in coastal and underwater structures in order to construct bridges, jetties, breakwaters and floating structures. However, concrete is more prone to deteriorate due to the aggressive environmental conditions in the atmospheric and splash zone due to chloride content in water, sulphate attacks, abrasion erosion caused by slit, sand and gravel, wetting and drying cycles and due to presence of waste and chemicals in water [13], [5]. These environmental parameters will cause cracking, spalling and corrosion which leads to incurring an enormous amount of money on repairing purposes and also this will reduce the structural health and safety of structures [23].
According to researchers, deterioration of concrete structures due to chloride induced reinforcement corrosion is a major problem around the world and reinforcement in partially submerged concrete structures is mainly corroded due to the ingress of chloride ions [18], [39]. According to Neville [20], a protective oxide layer that consists of γ-Fe2O3 is formed on steel which is generated soon after the hydration of concrete has started. Chloride ions that ingress inside concrete can be dissolved in pore solution (free chloride) or bound to the cement hydrates (bounded chloride) and only free chloride contributes to breaking this passive layer which results in corrosion [17]. When the concentration of chloride ions in the pore solution around the steel surface reaches the threshold value this film will be destroyed [4].
Conclusions
In this study, a rating model was developed to predict the rate of deterioration of the splash zone of marine concrete structures and the model was validated by assessing the current condition of 15 existing marine concrete structures. The model was developed based on FAHP and numerical definitions were used to avoid subjectivity of evaluators. According to the model, water quality has the highest priority for the deterioration of the splash zone of the structure and visual inspection, causal factors, crack detail and NDT have priority weights in the decreasing order. The proposed method can be used to rate the deterioration percentage of existing marine concrete structures in tropical countries and according to the results obtained from the model, proper remediation can be done. As future research work in this domain, freeze-thaw action can be taken into consideration in order to modify this model.