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

PDF URL: http://www.ije.ir/Vol32/No4/A/6-3046.pdf  
downloaded Downloaded: 47   viewed Viewed: 252

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.


1. Yamanouchi, H., Midorikawa, M., Nishiyama, I., and Watabe, M., “Seismic Behavior of Full‐Scale Concentrically Braced Steel Building Structure”, Journal of Structural Engineering, Vol. 115, No. 8, (1989), 1917–1929. 
2. Khatib, I., Mahin, S., and Pister, K., “Seismic behavior of concentrically braced steel frames”, UCB/EERC-88/01, Earthquake Engineering Research Center, University of California, Berkeley, CA, (1988).
3. Yoshino, T., and Karino, Y., “Experimental study on shear wall with braces: Part 2”, In Summaries of technical papers of annual meeting, Vol. 11, Architectural Institute of Japan, (1971), 403–404. 
4. Amiri, J. V., Goltabar, A. R. M., and Seifabadi, H. S., “Effect of the Height Increasing on Steel Buildings Retrofitted by Buckling Restrained Bracing Systems and TTD Damper”, International Journal of Engineering - Transactions A: Basics, Vol. 26, No. 10, (2013), 1145–1154. 
5. Sause, R., Ricles, J.M., Roke, D., Seo, C.Y., and Lee K.S., “Design of self-centering steel concentrically-braced frames”,  In Proceedings from the 4th International Conference on Earthquake Engineering, Taiwan, (2006).
6. Uriz, P., and Mahin, S. A., “Towards earthquake resistant design of concentrically braced steel structures”, PEER Report 2008/08, Pacific Earthquake Engineering Research Center, University of California, Berkeley, CA, (2008).
7. Lai, J.W., and Mahin, S.A., “Experimental and analytical studies on the seismic behavior of conventional and hybrid braced frames”, PEER Report 2013/20, Pacific Earthquake Engineering Research Center, University of California, Berkeley, CA, (2013).
8. Guo, Y.L., Zhang, B.H., Zhu, B.L., Zhou, P., Zhang, Y.H., and Tong, J.Z., “Theoretical and experimental studies of battened buckling-restrained braces”, Engineering Structures, Vol. 136, (2017), 312–328. 
9. Mohebkhah, A., and Farahani, S., “Seismic Behavior of Direct Displacement-based Designed Eccentrically Braced Frames”, International Journal of Engineering - Transactions C: Aspects, Vol. 29, No. 6, (2016), 752–761. 
10. Shen, J., Wen, R., and Akbas, B., “Mechanisms in two-story X-braced frames”, Journal of Constructional Steel Research, Vol. 106, (2015), 258–277. 
11. Wang, J., Dai, K., Yin, Y., and Tesfamariam, S., “Seismic performance-based design and risk analysis of thermal power plant building with consideration of vertical and mass irregularities”, Engineering Structures, Vol. 164, (2018), 141–154. 
12. Saffari, H., Damroodi, M., and Fakhraddini, A., “Assesment of Seismic Performance of Eccentrically Braced Frame with Vertical Members”, Asian Journal of Civil Engineering (Building and Housing), Vol. 18, No. 2, (2017), 255–269. 
13. Lee, K., and Bruneau, M., “Energy dissipation of compression members in concentrically braced frames: Review of experimental data”, Journal of structural engineering, Vol. 131, No. 4, (2005), 552–559. 
14. Chen, C. H., and Mahin, S., “Seismic collapse performance of concentrically steel braced frames”, In Proceedings of the Structures Congress and 19th Analysis and Computation Specialty Conference, Orlando, Florida., (2010).
15. Shaback, B., and Brown, T., “Behaviour of square hollow structural steel braces with end connections under reversed cyclic axial loading”, Canadian Journal of Civil Engineering, Vol. 30, No. 4, (2003), 745–753. 
16. Shen, J., Seker, O., Sutchiewcharn, N., and Akbas, B., “Cyclic behavior of buckling-controlled braces”, Journal of Constructional Steel Research, Vol. 121, (2016), 110–125. 
17. Minimum Design Loads for Buildings and Other Structures. ASCE 7-10. American Society of Civil Engineers, Reston, VA, (2010).
18. Specifications for Structural Steel Buildings. AISC 360-10. American Institute of Steel Construction, Inc. Chicago, IL, (2010).
19. Hsiao, P.C., Lehman, D. E., and Roeder, C.W., “Improved analytical model for special concentrically braced frames”, Journal of Constructional Steel Research, Vol. 73, (2012), 80–94. 
20. Mazzoni, S., McKenna, F., Scott, M.H., and Fenves, G.L., “OpenSees command language manual”, Pacific Earthquake Engineering Research Center, University of California, Berkeley, CA, (2006).
21. Ghanaat, Y., “Study of X-braced steel frame structures under earthquake simulation”, Report No. UCB/EERC-80/08, Earthquake Engineering Research Center, University of California, Berkeley, CA, (1980).
22. Fakhraddini, A., Fadaee, M. J., and Saffari, H., “A lateral load pattern based on energy evaluation for eccentrically braced frames”, Steel and Composite Structures, Vol. 27, No. 5, (2018), 623–632. 
23. Seismic rehabilitation of existing buildings. ASCE/SEI 41-13. American Society of Civil Engineers, Reston, VA, (2013). 

Download PDF 

International Journal of Engineering
E-mail: office@ije.ir
Web Site: http://www.ije.ir