کاهش خرابی ناشی از برخورد هواپیما به سازه‌های محافظ بتنی

نوع مقاله: پژوهشی

نویسندگان

گروه مهندسی عمران، دانشکده مهندسی، دانشگاه کاشان، کاشان، ایران

10.24200/j30.2020.54430.2646

چکیده

برخورد هواپیما به سازه‌های محافظ بتنی نیروگاه‌های هسته‌ای از جمله رویدادهایی است که می‌تواند پیامدهای زیست محیطی ناگواری به همراه داشته باشد. بارگذاری دینامیکی ناشی از برخورد انواع هواپیماها به صورت منحنی‌های فشار-زمان برای کاربردهای طراحی در مراجع مربوطه از جمله استانداردهای آژانس بین‌المللی انرژی اتمی ذکر شده است. اندرکنش پرتابه و پوسته محافظ بتنی و مودهای خرابی مربوطه هنوز موضوع بسیاری از مطالعات است. در این مقاله پدیده برخورد هواپیما به پوسته محافظ بتنی، با مدلسازی غیرخطی با در نظر گرفتن مدل‌های رفتاری بتن و فولاد متناسب با بارگذاری سریع و با در نظر گرفتن زوال مصالح در کرنش‌های زیاد به منظور مدلسازی هر چه دقیق‌تر پدیده‌های نفوذ و قلوه‌کنی با نرم‌افزار ANSYS AUTODYN مطالعه شده است. در این پژوهش اثر ضخامت پوسته و میزان آرماتور خمشی بر مودهای گسیختگی بررسی گردیده و پیشنهاد برای انتخاب ضخامت بهینه برای کنترل خرابی در پوسته محافظ ارائه شده است.

کلیدواژه‌ها


عنوان مقاله [English]

Damage reduction due to aircraft crash to concrete protective structures

نویسندگان [English]

  • Hassan Ostad-Hossein
  • Amir Hossein Boluri Kashani
Department of civil engineering, University of Kashan, Kashan, Iran
چکیده [English]

Terrible environmental effects maybe consequence of aircraft crash into protective concrete structures. Dynamic loading of aircraft crash are defined as pressure-time curves based on analytical methods in related references such as International Atomic Energy Agency (IAEA). It is obvious that impact loading is a function of many variables such as rigidity, mass and impact angle of projectile, and also rigidity and ductility of target which are mostly ignored in simplified analytical solutions. By developing numerical techniques it is a topic of interest to evaluate the effect of aircraft impact to structures more accurate. Because of its high performance in complex problem analysis such as high velocity impact loading, including interaction and large deformations, numerical approach is an appropriate tool for analyzing crash problems. In the numerical simulation method, details of projectiles and target structures, namely geometry, boundary conditions and interaction between the constituents can be considered to obtain the results with an acceptable accuracy. In crash cases, it is expected to have large variations in results due to huge material and geometric nonlinearities, therefor adjusting the accuracy and stability parameters to control elements erosion and zero energy modes removal is an important problem. In this paper RF-4 aircraft crash to concrete protective shell is investigated using nonlinear finite element analyses applying nonlinear material models for concrete and metals including strain rate for high velocity effects and erosion of elements in large strains to capture penetration and spalling occurrence by ANSYS AUTODYN software. Effect of concrete shell thickness and amount of flexural reinforcement on failure modes have been investigated. It is concluded that concrete shell thickness increasing, causes to reduction of scabbing and penetration depth. Optimum concrete thickness is obtained about 1.5 m, in which failure has significant reduction. In addition thickness increasing more than 1.5 m has not considerable effect on damage intensity and failure mode. Another result was that variation of flexural reinforcement between minimum and maximum amount has more protective effect in thinner thickness and penetration depth in thicker shells has less dependency on flexural reinforcement amount. Sensitivity analyses performed to determine week location, show that bottom cylindrical wall is more vulnerable than upper dome shaped roof.

کلیدواژه‌ها [English]

  • Aircraft crash
  • Concrete protective structure
  • Damage patterns
  • Nonlinear finite element using ANSYS AUTODYN
  • RHT material model for concrete