نوع مقاله: مقاله پژوهشی

نویسندگان

1 گروه مهندسی عمران، دانشگاه آزاد اسلامی، واحد سمنان، سمنان، ایران

2 گروه مهندسی عمران، واحد سمنان، دانشگاه آزاد اسلامی، سمنان، ایران

10.30478/jcsm.2019.167424.1109

چکیده

مواد مرکب سیمانی مسلح الیافی توانمند (HPFRCC) مصالحی هستند که به سبب وجود الیاف و ساز و کار پل زدن آنها، دارای رفتار سخت‌شوندگی کرنشی کششی بوده و قابلیت تشکیل ترک‌های چندگانه را دارند. این مصالح توانمند، فاقد مصالح سنگی درشت دانه بوده و الیاف به شکل تصادفی داخل آن توزیع می‌شود. در این مقاله بر مبنای یک کار آزمایشگاهی، از لایه‌های HPFRCC با ضخامت، طول و مقاومت‌های فشاری و کششی مختلف برای مقاوم سازی یک تیر بتن آرمه استفاده گردیده و با استفاده از روش اجزای محدود، تاثیر این متغیرها بر ظرفیت خمشی این تیر، بررسی شده است. نتایج نشان می‌دهد که افزایش مقاومت فشاری و کششی لایه‌ی تقویتی HPFRCC تاثیر چندانی بر ظرفیت تیر ندارد. همچنین افزایش ضخامت و طول لایه‌های HPFRCC، بار نهایی و شکل‌پذیری نمونه‌ها را افزایش می‌دهد. شکل‌پذیری نمونه‌ای که به طور کامل از مصالح  HPFRCC تشکیل شده است، نسبت به نمونه مرجع بتن مسلح، حدود 39 % افزایش می‌یابد.

کلیدواژه‌ها

عنوان مقاله [English]

Behavior of reinforced concrete beam strengthened by HPFRCC material

نویسندگان [English]

  • Ali Hemmati 1
  • Samira Ezzoddin 2

1 Civil Engineering Department, Islamic Azad University, Semnan Branch, Semnan, Iran

2 Department of Civil Engineering, Semnan Branch, Islamic Azad University, Semnan, Iran

چکیده [English]

 
High performance fiber reinforced cementitious composites (HPFRCC) are cement matrices with strain hardening behavior under tension loading. In these composites, the cement mortar with only fine aggregates is reinforced by random distributed fibers. In this material, multiple cracking in the HPFRCC occurs due to bridging mechanism of the fibers and subsequently, the strain hardening behavior is observed. In this paper, based on an experimental work, HPFRCC layers with different thicknesses and different lengths are used in lieu of normal concrete. Compressive and tensile strengths of the HPFRCC material are variable in these analytical models too. Finite element approach is used to investigate the effect of these parameters on the capacity of the reinforced concrete beam. Results show that increasing the compressive and tensile strength of the HPFRCC layers concludes to more final load and more ductility of the analytical beams. But this increasing effect is not significant. Moreover, increasing the thickness and length of the HPFRCC material concludes to more final load and more ductility in the retrofitted models. The ductility of the full HPFRCC beam is about 1.39 times more than that of the reinforced concrete beam.
 

کلیدواژه‌ها [English]

  • retrofitting
  • Reinforced concrete beam
  • HPFRCC
  • Ductility
  • ultimate load

 

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