پیشنهاد ضرایب طراحی لرزه‌ای برای قاب فولادی مهاربندی دارای حرکت گهواره‌ای

نوع مقاله : علمی - پژوهشی

نویسندگان

1 دانشگاه علوم و تحقیقات تهران

2 پژوهشگاه بین المللی زلزله و مهندسی زلزله

چکیده

سیستم قاب فولادی مهاربندی مرکزگرا با قابلیت برکنش کنترل شده توانایی کاهش خسارت لرزه‌ای از طریق هدایت آسیب به المان‌های میراگر قابل تعویض دارد. این مقاله به پیشنهاد ضرایب طراحی لرزه‌ای شامل ضرایب کاهش پاسخ، اضافه مقاومت و شکل پذیری برای قا‌ب‌های فولادی مرکزگرا دارای حرکت گهواره‌ای کنترل شده می‌پردازد. بدین منظور، ابتدا دوازده نمونه سیستم مرکزگرا متفاوت از نظر تعداد طبقات، محل قرارگیری قاب مهاربندی در پلان سازه و نوع خطر لرزه‌ای ساختگاه طراحی می‌گردد. مدل غیرخطی قاب دارای برکنش در نرم افزار اپنسیز به منظور شبیه‌سازی ایجاد مکانیرم در قاب و توالی خسارت در اجزای آن (کابل پس کشیده و میراگرهای جاری شونده قابل تعویض) توسعه داده شده است. ضرایب اضافه مقاومت و شکل پذیری سیستم قاب مرکزگرا با استفاده از تحلیل استاتیکی غیرخطی تعیین می‌گردد. همچنین تحلیل‌های دینامیکی فزاینده غیرخطی برای دستیابی به منحنی‌های شکنندگی حالت حدی فروریزش قاب‌های مورد مطالعه انجام می‌گیرد. با درنظرگیری عدم قطعیت موجود و اثر شکل طیفی، منحنی‌های شکنندگی اصلاح می‌گردد. با استفاده از منحنی‌های شکنندگی اصلاح شده بدست آمده، ضریب کاهش پاسخ پیشنهادی برای سیستم فولادی مرکزگرا با مقایسه نسبت حاشیه فروریزش تنظیم شده با معیارهای پذیرش ارزیابی می‌گردد. در انتها تاثیر پارمترهای مدل‌سازی و لرزه‌ای بر احتمال فروریزش سیستم بررسی می‌گردد. نتایج حاکی از آن است که قاب‌های کنترل شده مرکزگرا معیارهای پذیرش را تامین می‌نماید و طراحی این سیستم با ضرایب پیشنهادی حاشیه ایمنی کافی را در برابر فروریزش فراهم می‌آورد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Proposal for seismic design coefficients for rocking steel braced frame

نویسندگان [English]

  • Navid Rahgozar 1
  • Abdolreza S Moghadam 2
1 IAU
2 IIEES
چکیده [English]

Rocking steel braced frames are capable of reducing seismic damage through directing damage in energy dissipation elements. This paper quantifies seismic design factors for the controlled rocking self-centering braced frame including response modification, over-strength, and ductility parameters through probabilistic safety assessment methodology. For this purpose, twelve self-centering braced frames differ from the number of stories, plan location, and site class is designed. A nonlinear model is developed for the rocking braced steel frame in Opensees software to simulate the degrading and collapse of the frame and its components (post-tensioning strands and yielding replaceable damper). Over-strength and ductility factors of self-centering systems are determined using nonlinear static analysis. The incremental dynamic analysis is conducted to obtain collapse limit state fragility curves of self-centering frames. Considering total uncertainty and effects of spectral shape, the fragility curves are modified. Through modified fragility curves, proposed response modification factor is verified by comparing the adjusted collapse margin ratio with its acceptance criteria. Finally, the effects of modeling and seismic parameters on the collapse probability of the system are examined. Results indicate that controlled rocking systems are satisfied acceptance criteria and the design of the system with the proposed coefficients provide sufficient safety margin against collapse.

کلیدواژه‌ها [English]

  • Rocking braced steel frame
  • seismic design parameters
  • collapse assessment
  • collapse margin ratio
  • fragility curve
[1]    ASCE 7. (2005). Minimum design loads for buildings and other structures. ASCE 7- 05, American Society of Civil Engineers, Reston, Virginia.
[2]    IBC, ICC. (2006). International Code Council, Inc(formerly BOCA, ICBO and SBCCI). International building code, 4051(1), pp.60478-65795.
[3]    Iwata, Y. Sugimoto, H. and Kuguamura, H (2006). Reparability limit of steel structural buildings based on the actual data of the Hyogoken-Nanbu earthquake. In; Proc. 38th Jt. Panel Wind Seism. Eff. NIST Spec. Publ., 1057, USA, pp.23-32.
[4]    Ramirez, C. M. Miranda, E. (2012). Significance of residual drifts in building earthquake loss estimation. Earthq. Eng. Struct. Dyn., 41(11), pp.1477-1493.
[5]    FEMA, Federal Emergency Management Agency. Next-Generation Performance-Based Seismic Design Guidelines Program Plan for New and Existing Buildings. F. 445, Washington DC, USA (2006).
[6]    Group, T. G. W. (2010). Guidelines for performance-based seismic design of tall buildings. Berkeley: University of California (PEER Report No. 2010/05), California, USA.
[7]    Iwashita, K. Kimura, H. Kasuga, Y. and Suzuki, N. (2002). Shaking table test of a steel frame allowing uplift. J. of Struct. Constr. Eng., 13(6), pp. 47-54.
[8]    Midorikawa, M. Azuhata, T. Ishihara, T. and Wada, A. (2006). Shaking table tests on seismic response of steel braced frames with column uplift. Earthq. Eng. Struct. Dyn., 35(14), pp. 1767–85.
[9]    Wiebe, L. Christopoulos, C. (2014). Performance-based seismic design of controlled rocking steel braced frames. I: Methodological frame-work and design of base rocking joint. J. of Struct. Eng., 141(9): 04014226.
[10]    Tremblay R, Poirier LP, Bouaanani N, Leclerc M, Rene V, Fronteddu. (2008). Innovative viscously damped rocking braced steel frames. In: 14th World Conf. Earthq. Eng., Beijing, China.
[11]    Ajrab, J. J. Pekcan, G. and Mander, J. B. (2004). Rocking wall-frame structures with supplemental tendon systems. J. of Struct. Eng., 130(6), pp.895-903.
[12]    Grigorian, C. Grigorian, M. (2015). Performance control and efficient design of rocking-wall moment frames. J of Struct. Eng., 142(2): 04015139.
[13]    Wiebe, L. Christopoulos, C. Tremblay, R. Leclerc, M. (2013). Mechanisms to limit higher mode effects in a controlled rocking steel frame. 1: Concept, modelling, and low-amplitude shake table testing. Earth. Eng. Struct. Dyn., 42(7): 1053–1068.
[14]    Francesco, S. Palermo, A. Pampanin, S. (2015). Quasi-static cyclic testing of two-thirds scale unbonded posttensioned rocking dissipative timber walls. J of Struct. Eng., 142(4): E4015005.
[15]    Toranzo, L. Restrepo, J. Mander, J. and Carr, A. (2009). Shake-table tests of confined-masonry rocking walls with supplementary hysteretic damping. J. of Earthq. Eng., 13(6), pp.882-898.
[16]    Eatherton, M. R. and J. F. Hajjar. (2010). Large-scale cyclic and hybrid simulation testing and development of a controlled-rocking steel building system with replaceable fuses. Newmark Stru. Eng. Lab. University of Illinois at Urbana-Champaign, USA.
[17]    Ma, X. Krawinkler, H. and Deierlein, G. G. (2011). Seismic design and behavior of self-centering braced frame with controlled rocking and energy dissipating fuses. blume earthquake Eng (Vol. 174). Center TR.
[18]    Hall, K.S. Eatherton, M.R. and Hajjar, J.F. (2010). Nonlinear behavior of controlled rocking steel-framed building systems with replaceable energy dissipating fuses. Newmark Structural Engineering Laboratory. University of Illinois at Urbana-Champaign, USA.
[19]    Eatherton, M. R. Ma, X. Krawinkler, H. Mar, D. Billington, S. Hajjar, J. F. and Deierlein, G. G. (2014). Design Concepts for Controlled Rocking of Self-Centering Steel-Braced Frames. J. of Struct. Eng., 140(11).
[20]    Tahmasebi, E. Sause, R. Ricles J. M. Chancellor, N. B. and Akbas, T. (2014). Probabilistic Collapse Performance Assessment of Self-Centering Concentrically Braced Frames. In: Proc. 10th US National Conf. on Earthq. Eng., Anchorage, AK, USA pp. 5–21.
[21]    Ahmadi, O. Ricles, J. M. and Sause, R. (2014). Seismic collapse resistance of self-centering steel moment resisting frame systems. In: Proc. 10th US National Conf. on Earthq. Eng., Anchorage, AK, USA.
[22]    FEMA, Federal Emergency Management Agency. (2009). Quantification of Building Seismic Performance Factors. FEMA P695, Washington, D.C.
[23]    Gupta, A. and Krawinkler, H. (1999). Seismic demands for the performance evaluation of steel moment resisting frame structures. Doctoral dissertation, Stanford University.
[24]    Walsh, K. Q. and Kurama, Y. C. (2012). Effects of loading conditions on the behavior of unbonded post-tensioning strand-anchorage systems. PCI J., 57(1), pp.76-96.
[25]    ASTM. (2006). American Society for Testing and Materials International. Standard Specification for Steel Strand, Uncoated Seven-Wire for Prestressed Concrete, ASTM Standard A416/A416M-06, West Conshohocken, PA.
[26]    ACI ITG. (2009). American Concrete Institute Innovation Task Group 5. Requirements for design of special unbonded posttensioned precast shear wall satisfying ACI ITG-5.1 (ACI ITG-5.2-09) and commentary, ACI ITG -5.2-09, Farmington Hills, MI.
[27]    Ma, X. Borchers, E. Pena, A., Krawinkler, H. and Deierlein, G. (2010). Design and behavior of steel shear plates with openings as energy-dissipating fuses. John A. Blume Earthquake Engineering Center Technical Report, (173).
[28]    OpenSees Website, http://opensees.berkeley.edu.
[29]    AISC. (2005). American Institute of Steel Construction. Code of standard practice for steel buildings and bridges, AISC 303-05, Chicago, Illinois , USA.
[30]    Uriz, P. and Mahin, S. (2004). Seismic vulnerability assessment of concentrically braced steel frames. Int. J. of Steel Struct., 4(4), pp.239-248.
[31]    Elnashai, A. and Mwafy, A. (2002). Overstrength and force reduction factors of multistorey reinforced-concrete buildings. Struct. Des. of Tall Build., 11(5), pp.329-351.
[32]    Vamvatsikos, D. and Cornell, C. A. (2002). Incremental dynamic analysis. Earthq. Eng. Struct. Dyn., 31(3), pp.491-514.
[33]    Deierlein, G. G. Liel, A. B. Haselton, C. B. Kircher, C. A. and Principal, K. (2008). ATC-63 methodology for evaluating seismic collapse safety of archetype buildings. In: ASCE-SEI Struct. Congr., Vancouver, Canada , pp.24–6.
[34]    Haselton, C. B. Baker, J. W. Liel, A. B. and Deierlein, G. (2009). Accounting for ground-motion spectral shape characteristics in structural collapse assessment through an adjustment for epsilon. J. of Struct. Eng., 137(3), pp.332-344.