رفتار پس از ترک خوردگی نمونه های کششی ساخته شده از بتن فوق توانمند، مسلح شده با میلگرد GFRP

نوع مقاله : علمی - پژوهشی

نویسندگان

1 گروه مهندسی عمران، دانشکده فنی و مهندسی، دانشگاه زابل، زابل، ایران

2 دانشیار، دانشکده فنی و مهندسی، دانشگاه فردوسی مشهد

چکیده

امروزه استفاده از مصالح نوین نظیر بتن فوق توانمند و میلگردهای GFRP در صنعت ساختمان دارای گسترش روز افزونی می باشد. معمولاً از این نوع مصالح در ساخت سازه‌های بتن مسلح و یا ترمیم این نوع سازه ها استفاده می شود. با توجه به اینکه به دلیل ویژگی های میلگرد الیاف شیشه و همچنین نوع متفاوت سطح جانبی این نوع میلگرد، رفتار باند –لغزش بین بتن و میلگرد در اعضای بتن مسلح ساخته شده از میلگرد GFRP در مقایسه با اعضای مسلح شده با میلگردهای فولادی متفاوت می باشد، از اینرو شناخت و بررسی رفتار اعضای بتنی مسلح شده با میلگردهای GFRP در قبل و بعد از ترک خوردگی در عضو برای تحلیل غیر خطی رفتار این نوع اعضا ضروری می باشد.
از آنجائیکه بتن فوق توانمند به دلیل ویژگی های آن نظیر مقاومت فشاری بالا، نفوذپذیری کم، مقاومت در برابر سیکلهای یخبندان و .... به منظور کاهش ابعاد اعضای سازه و یا استفاده در سازه های خاص نظیر پل ها، نیروگاه های اتمی و........کاربرد زیادی دارد، در این پژوهش رفتار قبل و پس از ترک خوردگی نمونه های مسلح کششی ساخته شده از بتن فوق توانمند و میلگردGFRP مورد بررسی قرار گرفته است. برای دست یافتن به این هدف با انجام آزمایش کشش بر روی نمونه های استوانه ای به طول 850 میلی‌متر که با یک میلگردGFRP در مرکز مسلح شده اند تأثیر نوع میلگرد، قطر میلگرد و نسبت ضخامت پوشش بتن روی میلگرد به قطر میلگرد بر رفتار ترک‌خوردگی بتن فوق توانمند در کشش برای اعضای بتن مسلح بررسی‌شده است و برای حداقل،حداکثر و متوسط فاصله ترک ها و همچنین تنش کششی ترک-خوردگی در اعضای کششی با توجه به عوامل مؤثر بر آنهاروابط مناسب و کاربردی ارائه شده است.

کلیدواژه‌ها


عنوان مقاله [English]

Post - cracking behavior of the tensile specimens made from Ultra high performance concrete, reinforced by GFRP rebar

نویسندگان [English]

  • hossein ali rahdar 1
  • M. Ghalehnovi 2
1 Faculty Member, Faculty of Engineering, Zabol University
2 Associate professor, Faculty of Engineering, Ferdowsi University of Mashhad
چکیده [English]

Since it is very important to know the material's behavior to evaluate the nonlinear behavior of structures, it is necessary to know the tension stiffening phenomenon and its effect on the behavior of the reinforced concrete members to examine their behavior in tension. For a reinforced concrete member, the reinforcement confined concrete affects the member's behavior after being cracked in the spacing between two cracks, and the reinforcement rebar in the concrete member shows less strain than the bare rebar. This affects the width of cracks and the stiffness of the member under tension.
In this research the experimental method is used to tensile behavior of concrete members reinforced by GFRP rebar therefore the effect of rebar type, reinforcement ratio and c/d ratio on the cracking behavior of ultra high performance concrete (UHPC) is evaluated.
The results show that increasing the rebar cover to diameter ratio of all specimens, their initial stiffening increases before the cracking stage in concrete. Also, the tension stiffening effect does not change as the type of the rebar changes. Finally, the spacing of cracks, the way they are distributed and their behavior are discussed.
Keywords:
Ultra High performance concrete,
tensile strength
GFRP rebar,
Tensile member.
Cracking

کلیدواژه‌ها [English]

  • UHPC
  • tensile strength
  • GFRP
  • Tensile member
  • Cracking
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