Modares Civil Engineering journal
مهندسی عمران مدرس
MCEJ
Engineering & Technology
http://mcej.modares.ac.ir
1
admin
2476-6763
10.22034
fa
jalali
1396
4
1
gregorian
2017
7
1
17
2
online
1
fulltext
fa
ارزیابی عملکرد لرزه ای اتصال تیر– ستون بتنی تقویت شده با پوشش الیاف کربنی
Seismic performance assessment of concrete beam–column connection strengthened Carbon Fiber Reinforced Polimer
در قاب خمشی بتنآرمه، نیروی برشی قابل توجهی در اتصالات آن تحت بار جانبی ایجاد میشود که با تغییرشکلهای زیادی همراه است. لذا از مهمترین عوامل مؤثر بر رفتار قاب خمشی تحت بار جانبی، عملکرد صحیح اتصالات میباشد. در این تحقیق، ۶ الگوی تقویت اتصال تیر-ستون بتن مسلح تقویتشده با استفاده از ورقهای الیاف کربنی (CFRP) پیشنهاد شده و عملکرد لرزهای اتصال بررسی شده است. برای رسیدن به این هدف، ابتدا مدلسازی اتصال تیر-ستون تقویتشده با استفاده از نرمافزار اجزائ محدود آباکوس انجام شده است. در این مدل، مدلسازی بتن با استفاده از مدل الاستوپلاستیک آسیبدیده و ورقهای CFRP بهصورت الاستیک و ارتوتروپیک مدل شدهاند. سپس با استفاده از نتایج تحلیل، انتخاب بهترین الگوی تقویت اتصال تیر-ستون با ورقهای CFRP بر پایهی بهبود عملکرد لرزهای اتصالات از لحاظ میزان باربری، جذب انرژی، سختی اولیه و تغییر مکانیزم شکست اتصال تعیین شده است. نتایج نشان میدهد که چیدمان مناسب ورقهای CFRP، میتواند باعث افزایش میزان باربری، بار ترکخوردگی، سختی اولیه، استهلاک انرژی و جذب انرژی اتصال شود. همچنین الگوهای تقویتی پیشنهادی باعث انتقال شکست از بر ستون به تیر در اتصال میشود.
In the design process of a moment resisting frame (MRF), the principle of weak–beam and strong–column should been considered because the plastic hinge occurs in the beams. This mechanism is caused that the frame has capable of dissipating significant energy and remain stable in the inelastic region. Hence, the stability is defined as the ability of the frame to maintain its elastic level of resistance throughout the entire inelastic range of response. Using this principle, plastic hinges can be develop in the beams adjacent to the connections and usually very close to the column face. This mechanism allow cracks caused by the plastic hinging. The cracks can also propagate into the connection core region, and initiate a brittle failure mechanism. Furthermore, the mechanism has been not established in many existing MRFs designed based on the previous codes. Hence, the methods have been proposed and developed in order to relocate the plastic hinge away from the column face. Fiber Reinforced Polymer (FRP) has been used as a strengthening solution of beam–column connections and successfully reported for retrofitting existing structures. In fact, the use of a web–bonded FRP retrofitting system can control the mechanism of plastic hing and provide the strong–column weak–beam concept. Due to the many advantages, such as high strength, low weight, endurance and convenience, Carbon Fiber–Reinforced Polimers (CFRPs) have been widely used in strengthening concrete structures.<br /> However, the strength and stiffness of CFRP are severely reduced at elevated temperatures, which will affect the strengthening effect seriously.<br /> In this study, six schemes of strengthened concrete beam–column connection using CFRP are proposed and the seismic performance of the strengthened connection is investigated. In order to achieve this purpose, seven scaled–down RC exterior joint of a typical ordinary MRF are chosen and modeling this strengthened connection is implemented in the general finite element program, ABAQUS software. In the finite element model of strengthened concrete beam–column connection, the concrete is modeled using the damaged plastic model. The sheets of CFRP are also considered as the elastic and orthotropic model. These schemes of strengthened concrete beam–column connection are tested under moderately monotonic/cyclic loads. In order to verify the finite element model of the connection, the analysis results of this model is compared with the experimental investigation on the external beam–column connection repaired strengthened using CFRP. The results demonstrates the verification of the finite element model. The selection of the best scheme of strengthened concrete beam–column connection using CFRP is based on the improvement of the seismic performance of connection such as the load–carrying capacity, the energy absorption, the initial stiffness and changing failure mechanism of connection. The nonlinear results show that the proper layout of CFRP sheets can increase the load–carrying capacity, the energy absorption and the initial stiffness of connections. Furthermore, the proposed schemes of strengthened concrete beam–column connection are caused that the failure is relocated from the column face and located in beam. Therefore, the proposed best scheme of strengthened concrete beam–column connection using CFRP can be recommended and utilized in the practical projects of concrete structures.
اتصال تیر–ستون,تقویت اتصال,ورقهای الیافی کربنی,بهبود عملکرد لرزهای
beam–column connection,strengthening connection,Carbon Fiber Reinforced Polimer,Improvement of seismic performance
45
55
http://mcej.modares.ac.ir/browse.php?a_code=A-16-16315-1&slc_lang=fa&sid=16
mohsen
khatibinia
محسن
خطیبی نیا
100319475328460054653
100319475328460054653
Yes
university of birjand
دانشگاه بیرجند
جاسم
بنی اسد
100319475328460054652
100319475328460054652
No
دانشگاه بیرجند
حمیدرضا
ناصری
100319475328460053928
100319475328460053928
No
دانشگاه بیرجند