بررسی آزمایشگاهی رفتار اتصال های تیر به ستون بتنی با کامپوزیت های سیمانی مهندسی حاوی نانولوله ی کربن

نوع مقاله : پژوهشی

نویسندگان

1 دانشکده ی فنی و مهندسی، دانشگاه رازی

2 دانشکده ی فنی و مهندسی ، دانشگاه رازی

چکیده

در رفتار اتصال‌های خارجی تیر به ستون تحت بارگذاری چرخه‌یی پرداخته شده است. در پژوهش حاضر، سه اتصال بتنی آزمایش شدند که یکی از آن‌ها به‌عنوان نمونه‌ی مرجع و در ۲ اتصال دیگر، ناحیه‌ی مفصل خمیری تیر به ستون با E‌C‌C و C‌N‌T-E‌C‌C جایگزین شده است. پارامترهای اصلی درنظر گرفته شده، شامل: منحنی‌های هیسترزیس لنگر ـ تغییرمکان نسبی، ظرفیت جذب انرژی و توزیع ترک‌ها بوده است. نمونه‌های آزمایشگاهی تحت بارگذاری چرخه‌یی در انتهای تیر با کنترل تغییرمکان قرار گرفتند. بارگذاری تا زمانی که کاهش بار به بیش از ۳۰ الی ۴۰ درصد بیشینه‌ی بار وارده می‌رسید، ادامه یافت. نتایج آمایشگاهی نشان می‌دهد که با استفاده از مصالح توانمند ذکر شده، شکل‌پذیری و جذب انرژی اتصال‌های خارجی تیر به ستون به‌صورت مؤثری بهبود می‌یابد.

کلیدواژه‌ها


عنوان مقاله [English]

Experimental Investigation of the concrete beam-column joints behavior with CNTs modified engineering cementitious composite

نویسندگان [English]

  • E. khalilzadeh vahidi 1
  • M. Rezaei 2
1 F‌a‌c‌u‌l‌t‌y o‌f E‌n‌g‌i‌n‌e‌e‌r‌i‌n‌g R‌a‌z‌i U‌n‌i‌v‌e‌r‌s‌i‌t‌y
2 F‌a‌c‌u‌l‌t‌y o‌f E‌n‌g‌i‌n‌e‌e‌r‌i‌n‌g R‌a‌z‌i U‌n‌i‌v‌e‌r‌s‌i‌t‌y
چکیده [English]

Carbon nano-materials, especially Carbon nanotubes (CNTs(, are the most prospective advanced materials for application in cement-based products for the construction industry due to their excellent material properties. An appropriate design for beam-column joint structures is required to meet the requirements of strength and ductility to prevent any sudden failure. Under seismic action, this beam-column joint zone is considered the most sensitive zone that undergoes different shear stresses in different deflections. The seismic performance of beam-column connections and joints can be enhanced by using improved details in the joints, ensuring a strong connection behavior. However, the use of dense reinforcements brings about executive problems such as lack of concrete condensation. This paper investigates the effect of Engineering Cementitious Composites containing Carbon Nanotubes (ECC-CNT) on the behavior of RC exterior beam-column joints under reversed cyclic loading. In this study, three beam-column concrete joints were tested, one of which was the reference specimen. The two other joints of the critical area of beam-column connection were replaced with Engineering Cementitious Composite (ECC) and ECC-CNT. The main parameters considered include the moment-deflection relationship, the energy absorption capacity, hysteresis curve, and crack propagation. The specimen was subjected to a reversed cyclic loading under control deformation at the tip of the beam. Loading continued until the load dropped to more than 30-40% of the maximum load. Also, to simulate the actual sample, the compressive load of fifteen tons continuously entered the column. The mixing technique for producing highly dispersed nanomaterial in cement mortar is crucial as it directly affects the mechanical properties of the cementitious composite. In this study, a surfactant (plasticizer) and Arabic Gum were used in order to get a homogenous dispersion of CNT in water. According to the results in the sample containing CNT in the plastic joint, it absorbs the highest amount of energy at the end of loading, which was 28% and 55% higher than ECC and NC, respectively. In addition, results indicated that the use of ECC-CNT in the plastic bonding zone had a significant effect on the energy absorption and relative deformation of the joints.

کلیدواژه‌ها [English]

  • experimental investigation
  • reinforcement concrete
  • joints
  • Carbon Nanotubes (CNT)
  • engineering cementitious composite (ECC)