بررسی رفتار نمونه های بتنی ساخته شده با افزودنی های الیاف فلزی، میکروسیلیس،خاکستر بادی و الیاف هیبریدی تحت الگوهای مختلف بارگذاری

نوع مقاله : علمی - پژوهشی

نویسندگان

1 استادیارگروه مهندسی عمران، واحد کرمانشاه، دانشگاه ازاد اسلامی، کرمانشاه، ایران

2 کارشناس ارشد مهندسی سازه، واحد کرمانشاه، دانشگاه ازاد اسلامی، کرمانشاه، ایران

10.22065/jsce.2020.182908.1840

چکیده

الیاف در بتن گسیختگی نرم را در پی دارد و نمونه‏های فشاری و کششی پس از شکست، از هم گسیخته نمی شوند، این موضوع ‏از جمله محاسن الیاف فلزی خصوصاً الیاف موجدار سینوسی و قلابدار در هنگام وقوع زلزله می باشد، که فرصت لازم را برای ‏فرار به ساکنین می دهد. الیاف فلزی علاوه بر تأثیر مثبت در ویژگی های مکانیکی، سبب بهبود ماتریس بتن، تأمین ‏شکل‏پذیری و پاسخگویی به بار ضربه و نیز کنترل عرض و انتشار ترک می گردد. در این تحقیق با توجه به اینکه استفاده از ‏خاکستر بادی و میکرو سیلیس علاوه بر بهبود کارایی و دوام بتن در حفظ سلامت محیط زیست نیز مؤثر می باشد جهت ‏جایگزینی به جای سیمان استفاده ‏گردید.‏ در ادامه با تهیه نمونه هائی، مقاومت فشاری وکششی بتن بدون الیاف، و بتن حاوی الیاف فولادی در شش درصد ‏مختلف(‏‎0/4‎‏، ‏‎0/6‎‏، ‏‎0/8‎‏، 1، ‏‎1/2‎‏ و ‏‎1/5‎‏) و ترکیب الیاف فلزی و پلی پروپیلن در 3 ترکیب مختلف (‏‎0/3PP+0/8SF‎‏ و ‏‎0/4PP+0/4SF‎‏ و‎0/15PP+1/5SF‎‏) بررسی شده و پس از دستیابی به درصد بهینه (درصدی که بیشترین مقاومت فشاری و ‏کششی را با درنظر گرفتن ملاحظات اقتصادی ارائه دهد)، تحت پروتکل بارگذاری 02/97 - ‏BD‏/‏SAC‏، ضمن استخراج ‏پارامترهای لرزه ای و بررسی منحنی های هیسترزیس، جذب انرژی، تغییر مکان جانبی به تأثیرات استفاده از الیاف ‏مذکورپرداخته شد. ‏در مرحله آخر تحقیق با توجه به خواص عمده مواد پوزولانی، با افزودن خاکستربادی و میکروسیلیس به بتن حاوی الیاف ‏فلزی در درصد بهینه الیاف فلزی بدست آمده، ضمن بررسی و مقایسه آن با بتن حاوی الیاف فلزی و بتن فاقد الیاف و تعیین ‏درصد مناسب جایگزینی سیمان به تأثیر استفاده از خاکستربادی و میکروسیلیس در جلوگیری از کمانش بادبندهای کمانش ‏ناپذیر پرداخته شد.‏

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Investigation on the Behavior of Concrete with Optimum Percentage of Steel Fiber, Microsilica, Fly Ash and Hybrid Fiber under Different Loading Pattern

نویسندگان [English]

  • Javad Esfandiari 1
  • Omid Heidari 2
1 Department of Civil Engineering, Kermanshah Branch, Islamic Azad University, Kermanshah, Iran
2 Department of Civil Engineering, Kermanshah Branch, Islamic Azad University, Kermanshah, Iran
چکیده [English]

While the fibers in concrete cause soft rupture, the compressive and tensile samples are not ruptured after failure. This is one of the benefits of metallic fibers, especially the sinusoidal and hooked fibers: using these gives residents the opportunity to escape during an earthquake. In addition to positively impacting mechanical properties, metal fibers improve the matrix of concrete, provide ductility and response to impact load, and control crack width and propagation. Fly ash and micro-silica improve the durability and performance of concrete and are effective in protecting the environment: they can, thus, be used to replace cement. In this study, the samples’ compressive and tensile strength was prepared: they were of non-fibrous concrete and concrete containing steel fibers with 6 different percentages (0.4, 0.6, 0.8, 1, 1.2, 1.5). They were also composed of metallic fiber and polypropylene in three different compositions (0.3PP + 0.8SF, 0.4PP + 0.4SF, and 0.15PP + 1.5SF). These were investigated: seismic parameters were extracted after achieving the optimal percentage (the percentage with the highest compressive and tensile strength given economic considerations) under the loading protocol SAC/BD 97.02. This allowed investigation of the curves of hysteresis, energy absorption, lateral displacement, and effects of the use of these fibers. The major properties of pozzolanic materials were considered in the last step of this research: fly ash and microsilica were added to concrete containing metal fibers with the optimum percentage of metallic fibers. These were compared with concrete containing metallic fibers and non-fiber concrete. Thereafter, the appropriate percentage of cement replacement was determined so as to better understand the effect of the use of fly ash and microsilica in preventing the buckling of buckling restrained braces.

کلیدواژه‌ها [English]

  • buckling restrained braces
  • metal fibers
  • Polypropylene Fibers
  • Ductility
  • Energy absorption
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