بررسی آزمایشگاهی و تحلیلی تاثیر محصورشدگی بر رفتار تیرهای بتنی مسلح‌شده با میلگردهای پلیمری شیشه‌ای

نوع مقاله : علمی - پژوهشی

نویسندگان

1 گروه عمران، دانشکده مهندسی، دانشگاه زابل

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

3 گروه مهندسی عمران، دانشگاه سیستان و بلوچستان

4 دانش آموخته دوره کارشناس ارشد سازه، دانشگاه آزاد اسلامی، زاهدان، ایران

چکیده

میلگردهای پلیمری مسلح الیافی شیشه‌ای(GFRP) مقاومت کششی بالا و مقاومت زیاد در برابر خوردگی دارند در این پژوهش، به بررسی اثرات محصورکنندگی میلگردهای عرضی فولادی تیرهای بتنی مسلح شده با میلگردهای طولی پلیمری شیشه‌ای پرداخته شده است برای این منظور شش نمونه‌ی تیر بتنی با ابعاد مقطع عرضی 20 و 30 سانتی‌متر و طول دهانه‌ی بارگذاری 2 متر ساخته شدند. میلگردهای طولی تیرها دارای سطح مقطع عرضی با مقدارهای 7/1، 6/2 و 5/3 برابر مقدار متوازن بودند. میانه‌‌ی سه تا از تیرها به کمک خاموت‌های فولادی با فاصله‌ی کم، مسلح شدند. این نمونه‌ها دورگیر شده نامیده شدند. نمونه‌ها به صورت استاتیکی زیر آزمایش چهار نقطه‌ای قرار گرفتند. در بررسی رفتار نمونه‌ها از پارامترهای مقاومت تسلیم نخستین، سختی بخش ترک‌خوردگی، نیروی نهایی و شاخص شکل ‌پذیری استفاده شد. نتایج آزمایش‌ها نشان می‌دهد که محصور شدگی سبب افزایش سه پارامتر نخست به ترتیب تا حدود 35 ، 27 و 29درصد شده است. شاخص شکل ‌پذیری برای دو نمونه‌ یا میلگرد طولی 7/1 و 3/2برابر متوازن، حدود 6 و 22 درصد کاهش و در نمونه‌ی دیگر، حدود 6 درصد افزایش را نسبت به نمونه‌های شاهد نشان داد. همچنین رابطه‌های تحلیلی موجود برای تخمین ظرفیت تیرهای دورگیر نشده و دورگیر شده بکار رفت که خطای آن بین 5 تا 16 درصد بود و این بیانگر انطباق خوب نتایج تحلیلی با نتایج آزمایش است.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Experimentally and Analytically Investigating Effect of Confinement on Behavior of RC Beams Reinforced by GFRP

نویسندگان [English]

  • Mahmoud-Reza Hposseini-Tabatabaei 1
  • hossein ali rahdar 2
  • Seyed Roohollah Mousavi 3
  • Seyyed Mostafa Tabatabaei 4
1 Civil Engineering depatrtment
2 Faculty Member, Faculty of Engineering, Zabol University
3 Assistant Professor, Dept. of Civil Engineering, Univ. of Sistan and Baluchestan
4 Department of Civil Engineering, Islamic Azad University of Zahedan, Zahedan, Iran
چکیده [English]

Glass Fiber Reinforced Polymer (GFRP) rebars have high tensile strength and high resistance against corrosion. This study addressed the investigation of the confining effects of the transverse steel rebars on concrete beams reinforced using GFRP rebars. For this purpose, six beam specimens with cross-section dimensions of 20 and 30 cm and a span length of 200 cm were constructed. The rebars had cross-section area values of 1.7, 2.6, and 3.5 times the balance value. The middle of three beams was reinforced using stirrups with small spacing. These specimens were called confined beams. The specimens were tested under four-point static loading. The behavior of the unconfined and confined specimens was evaluated using the parameters of the initial yield strength, the stiffness of the cracking part, the ultimate load, and the ductility index. The experimental results indicate that confining the beams by steel stirrups increased the first three behavioral parameters to about 35, 27, and 29 percent, respectively. The ductility index for the two samples, having the longitudinal rebars of 2.6 and 3.5 times the balanced amount, decreased by about 6 and 22 percent. The other sample's ductility index increased approximately 6 percent compared to the control samples. Moreover, the capacities of both unconfined and confined specimens are estimated by existing analytical relationships with an error of 5 to 16 percent, having good agreements with the experimental results.





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کلیدواژه‌ها [English]

  • Reinforced concrete beam
  • GFRP
  • Transverse rebars
  • Bending strength
  • Flexibility
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