عملکرد لرزه‌ای سازه‌های نامتقارن جرمی جداسازی شده فولادی با سیستم‌های مهاربندی شورون، ضربدری و زیپر

نوع مقاله : مقاله پژوهشی

نویسندگان

1 گروه مهندسی عمران، دانشکده فنی مهندسی دانشگاه خوارزمی، تهران، ایران

2 گروه عمران، دانشکده فنی و مهندسی دانشگاه خوارزمی تهران ایران

چکیده

از روش‌های موثر مقابله با اثرات زمین‌لرزه بر سازه استفاده از سیستم جداساز لرزه‌‏ای است. در این مقاله عملکرد سازه‌های نامتقارن جداسازی شده فولادی با سیستم‌های ‏مهاربندی مختلف تحت اثر مولفه‌های افقی و قائم بررسی شده است. بدین منظور 3 نوع سیستم مهاربندی شورون، ضربدری و زیپر در سازه‌های 5 و 10 طبقه با ایجاد ‏نامتقارنی 10% و 20% درصدی ناشی از خروج از مرکزیت جرمی تحت اثر مولفه‌های قائم و افقی ‏زلزله مطالعه گردید. تحلیل تاریخچه زمانی ‏غیر‌خطی با 7 شتاب‌نگاشت منتخب حوزه نزدیک انجام شده ‌است. ابتدا سازه متقارن در دو حالت پایه ثابت و جداسازی شده تحلیل شد و سپس اثر نامتقارنی در دو حالت خروج از ‏مرکزیت جرمی 10% و 20% در سازه‌های مورد نظر مورد مقایسه قرار گرفت. متوسط مقدار نیروی برشی، دریفت و دوران طبقات و انرژی ورودی به سازه، پارامترهای مورد بررسی در این مقاله هستند. با افزایش خروج از مرکزیت جرمی سازه میزان جذب انرژی ورودی سازه توسط جداساز کاهش و برش پایه افزایش یافته است. در میان سیستم‌های مهاربندی متخلف، انرژی جذب شده توسط سیستم جداساز در سازه با مهاربند زیپر 53% افزایش یافته و میزان برش پایه 80% کاهش داشته است. بر اساس نتایج تحلیل، جداسازی از پایه در سازه با مهاربند ضربدری در حالت متقارن و نامتقارن جرمی، سبب کاهش بیش از 70% دوران طبقات نسبت به سایر سیستم‌های مهاربندی شده است.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Seismic performance of asymmetric isolated steel structures with different bracing systems

نویسنده [English]

  • Seyedmohammadreza Hsseini 1
1 Faculty of Engineering, Kharazmi University, Tehran, Iran
چکیده [English]

In this paper, the seismic performance of asymmetric isolated structures with different bracing systems under near-fault strong ground motions is investigated. Non-linear dynamic analyses are performed under the simultaneous application of horizontal and vertical components of seismic acceleration. For this purpose, three types of chevron, cross and zipper bracing systems in 5 and 10-story structures with 0%, 10% and 20% mass eccentricity have been studied. Non-linear time history analysis is performed by seven selected accelerograms. First, the symmetrical structure was analyzed in fixed and isolated base states. Then, the asymmetric effect on two eccentricity cases 10% and 20% in the target structures, was compared. The parameters studied in this paper are the average shear force, drift and rotation of floors, and input energy to the structure. With an increasing eccentricity of the structure, the energy absorption by the isolator is reduced and the base shear is increased. Among the different bracing systems, the energy absorbed by the isolation system in the structure with zipper bracing increased by 53% and the base shear rate decreased by 80%. Based on the analysis results, base-isolation in the structure with cross-bracing in symmetrical and asymmetric has caused a reduction of more than 70% of the floor rotation compared to other bracing systems.

کلیدواژه‌ها [English]

  • seismic isolator
  • asymmetric structures
  • cross brace
  • chevron brace
  • zipper brace
[1] A. Chopra, Dynamics of Structures. Theory and Applications toEarthquake Engineering, 2017.
[2] F. Naeim and J. M. Kelly, "Design of seismic isolated structures: from ‎theory to practice," John ‎Wiley & Sons, 1999.
[3] R. Jangid, "Optimum frictional elements in sliding isolation systems," Computers & ‎Structures, vol. 76, pp. 651-661, 2000.
[4] H. ‎Shakib and A. Fuladgar, "Effect of vertical component of earthquake on the response of ‎pure-friction base-isolated asymmetric buildings," Journal Engineering Structures, pp. 1814-1850, 2003
[5] K. Ryan and A. Chopra, "Estimation of seismic demands on isolators in asymmetric buildings using ‎non-linear analysis," Earthquake Engineering & Structural Dynamics, vol. 33, pp. 395-418, 2004.
[6] M. De Stefano and B. Pintucchi, "A review of research on seismic‏ ‏behavior of irregular building ‎structures," Earthquake Engineering, vol. 2, pp. 285-308, 2008.
[7] D. Koren and V. Killar, "Seismic behaviour of asymmetric base isolated structures with various distributions of isolators," Engineerring Structures, vol. 31, pp. 910-921, 2009.
[8] S. Etedali and M. R. Sohrabi, "Torsional Strengthening of Base-Isolated Asymmetric Structures by Increasing ‎the Flexible Edge Stiffness of Isolation System," International Journal of Civil & Environmental Engineering, vol. 11, pp. 51-59, 2011.
[9] F. Khoshnudian and D. Motamedi, "Seismic Response of Asymmetric Steel Isolated Structures Considering Vertical Component of Earthquakes," vol. 17, pp. 1333-1347, 2013.
[10] S. Etedali and M. Sohrabi, "A proposed approach to mitigate the torsional ‎amplifications of asymmetric base-isolated buildings during earthquakes," Journal of civil ‎engineering, vol. 20, pp. 768-776, 2015.
[11] N. Narimani and D. Pourian, "Comparison of using LRB in moment steel frame and concentrically brace frame," Journal of Civil Engineering and Structures , pp. 28-36, 2018.(In persian)
[12] Ras and N. Boumechra, "Dissipation’s Capacity ‎Study of Lead–Rubber Bearing ‎System in Seismic Steel Structures Design," Arabian Journal for Science and Engineering, pp. 3863-3874, 2017.
[13] Suthar and R. Noval, "Seismic Response of Symmetrical and Asymmetrical Structure with Base Isolators," vol. 5, no. 09, 2017.
[14] R. Irwan, R. Sjahril A, L. Yuskar and Y. Hendro, "Comparative Analysis of Fixed base and Isolated Structure in L Shape Plan with Time History Analysis based on ASCE7-16," IOP Conf. Series: Materials Science and Engineering 473, 2019.
[15] M. Kangda and S. Bakre, "The Effect of LRB ‎Parameters on Structural Responses for Blast and ‎Seismic Loads," Arabian ‎Journal for Science and Engineering, vol. 43, no. 4, p. ‎‎1761–‎‎1776, 2018.
[16] M. Bhandari, "Prediction of inelastic response of base-isolated building frame by pushover analysis," Asian Journal of Civil Engineering, vol. 21, p1171-1182, 2020.
[17] v. Killar and s. Petrovcic, "Seismic analysis of an asymmetric fixed base and base-isolated ‎high-rack steel structure," Engineerring Structures, vol. 33, pp. 3471-3482, 2011.
[18]  N. Mozafari, E.Boghlati , " Comparison of the effect of LRB and universal base separators on the seismic response of steel buildings with special bending frame," 9th International Congress of Civil Engineering, Isfahan University of Technology, 2012(In persian)
[19] C. E. Seguin, J. Almazan and J. la liera, "Torsional balance of seismically isolated asymmetric structures," Journal of Engineering Structures, vol. 46, pp. 703-717, 2013.
[20] M. Ismail, "Elimination of Torsion and Pounding of Isolated Asymmetric Structures under ‎Near-Fault Ground Motions," Structural Control and Health Monitoring, vol. 22, pp. ‎‎1295-1324,, 2015.
[21] L. Landi, G. Gianluca and P. P. Gianluca, "Comparison of different models for friction pendulum isolators in structures subjected to horizontal and vertical ground motions," Soil Dynamics and Earthquake Engineering, vol. 81, pp. 75-83, 2016.
[22] M. Gholhaki and S. Sabouri, "Effect of Ductility Factor on Force Modification Factor of Thin Steel Plate Shear Walls," Journal of Structure & Steel, p. 52, 2009.(In persian)
[23] T. Yang, "Hybrid Simulation Evaluation of The Suspended Zipper Braced Frame," ‎‎8th us national conference on earthquake engineering, 2006.
[24] National Building Regulations of Iran , Design and Construction of Steel Buildings, 10th Issue, Building and Housing Research Center, Iran, 2013. (In persian)
[25] ASCE/SEI7-16, Minimum Design Loads and Associated Criteria for Buildings and Other Structures (7-16), CA: Civil Eng, 2017.
[26] BHRC, Iranian Code of Practice for Seismic Resistant Design of Buildings: Standard No.2800 (4th Revision), Iran: Building and Housing Research Center, 2014. (In persian)
[27] Guideline for Design and Practice of Base Isolation Systems in Buildings No.523, Iran: Vice Presidency for Strategic Planning and Supervision, 2010.
[28] PEER, "Base Strong Motion Data," 2016. [Online]. Available: http://ngawest2.berkeley.
[29] A. Mansouri and F. Meshkinfam Hesari, "Evaluation of the Seismic Behavior of Asymmetric Base Isolated Braced Steel Structures," Journal of Structure & Steel, pp. 25-38, 2018.(In persian)