IJE TRANSACTIONS A: Basics Vol. 32, No. 4 (April 2019) 495-502    Article in Press

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S. S. Seyedjafari Olia, H. Saffari and A. Fakhraddini
( Received: December 29, 2018 – Accepted: March 09, 2019 )

Abstract    Concentrically braced frames (CBFs) are one of the efficient lateral load resisting systems in high seismicity regions. One of the common problems with the use of concentrically braced frames is limitation in the architectural application and position of the openings. Two-story X braced frames have more advantages than other configurations of concentrically braced frames, since in many cases the position of the openings due to the need for architectural spaces and executive imperfections causes the use of asymmetric X-braced frames, present study tries to evaluate the seismic behavior of asymmetric two-story X braces. In this study, the behavior of these braces has been studied. For this purpose, firstly, several symmetric two-story X braced frames are modeled by OpenSees software. Then, by changing the position of braces to beam connection, the new asymmetrical braces are obtained which initially designed. Finally, parameters such as stiffness, strength and stable hysteresis cycle of asymmetric systems are compared with symmetrical braces by nonlinear static and dynamic analysis. The results show that if asymmetric braces are distributed symmetrically in the structure, they do not lose their ability in comparison with the symmetrical models.


Keywords    Asymmetric Two-Story X-braced Frames; Concentrically Braced Frames; Seismic Performance; Hysteresis Cycle; Ductility



قاب‌های مهاربندی شده همگرا یکی از سیستم‌های موثر در برابر بارهای جانبی در مناطق با لرزه خیزی بالا محسوب می‌شوند. یکی از مهمترین مشکلات استفاده از بادبندهای همگرا، محدودیت در فضای معماری و بازشوها می‌باشد. از آنجا که در بسیاری از موارد موقعیت بازشوها به علت نیاز معماری از یک سو و نقص‌های اجرایی از سوی دیگر باعث لزوم استفاده از بادبندهای X شکل نامتقارن می‌گردد. در مقاله حاضر رفتار این بادبندها مورد بررسی قرار گرفته است. بدین منظور، ابتدا نمونه‌هایی از مهاربندهای X دو طبقه متقارن توسط نرم‌افزار OpenSees مدل‌سازی شده است. سپس با تغییر موقعیت گره میانی از مرکز تیر این بادبندها به شکل نامتقارن درآمده‌اند. بادبند نامتقارن جدید طراحی شده و تحت آنالیز استاتیکی و دینامیکی غیرخطی قرار گرفته‌اند و در رابطه با سختی، مقاومت و چرخه هیسترزیس پایدار در مقایسه با بادبندهای متقارن بحث شده است. نتایج بدست آمده نشان می‌دهد که بادبندهای نامتقارن افت چشمگیری در پارامترهای مذکور نسبت به بادبندهای متقارن ندارند.


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