ارزیابی اثر مهاربند دوبخشی و سه‌بخشی در بهبود رفتار لرزه‌ای قاب با مهاربندی پشتیبان‌قوی

نوع مقاله : مقاله پژوهشی

نویسندگان

گروه مهندسی عمران، دانشکده مهندسی گرگان، دانشگاه گلستان،گرگان،ایران.

چکیده

قاب‌های مهاربندی فولادی، از سیستم‌های مقاوم کارآمد در برابر بارهای لرزه‌ای هستند. بااین‌وجود، قاب‌های مهاربندی فولادی چندطبقه در پاسخ به لرزش‌های شدید زمین، تمایل به تمرکز نیازهای لرزه‌ای در یک یا چند طبقه دارند. ازاین‌رو در سالیان اخیر مکانیزم‌هایی ارائه شده تا نیازهای غیرالاستیک را در ارتفاع سازه توزیع کند. سیستم قاب پشتیبیان‌قوی از جمله تلاش‌های صورت گرفته در این زمینه است. این سیستم با استفاده از یک خرپا الاستیک در ارتفاع سازه، بازتوزیع نیازها را در سایر طبقات انجام می‌دهد. در اکثر مطالعات صورت‌گرفته از مهاربندهای فولادی مرسوم به عنوان المان اتلاف انرژی استفاده شده است در حالی که به علت کمانش مهاربندها، در این سازه‌ها اتلاف انرژی مناسبی دیده نمی‌شود. در این مطالعه امکان بهبود رفتار قاب مهاربندی پشتیبان‌قوی با مهاربندهای هلالی شکل (دوبخشی) و مهاربند تراپوزاید (سه بخشی) مورد ارزیابی قرار گرفت. در ابتدا به‌منظور انعطاف‌پذیری بیشتر در طراحی، مهاربند تراپوزاید معرفی شد و در انتها، امکان بهبود رفتار قاب مهاربندی پشتیبان‌قوی با اضافه نمودن مهاربند هلالی‌شکل و تراپوزاید با تحلیل استاتیکی غیرخطی مورد ارزیابی قرار گرفت. نتایج بیانگر آن بود که استفاده از این مهاربندها، ضمن بهبود اتلاف انرژی سازه تا 440/9% و افزایش ظرفیت برش قابل‌تحمل در سازه تا 57%، سختی سازه را به شکل قابل‌توجهی افزایش نداده (حداکثر 14%) و نیروهای ایجاد شده در المان‌های خرپا الاستیک، توزیع یکنواختی را در ارتفاع سازه شکل می‌دهند.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Evaluation of the Effect of Two-Part and Three-Part Braces on the Seismic Behavior of Strongback Braced Frames

نویسندگان [English]

  • Aryan Fatahzadeh
  • Ali Biglari
Department of Civil Engineering, Golestan University
چکیده [English]

Steel bracing frames are efficient systems for resisting seismic loads. However, multi-story steel bracing frames tend to concentrate seismic demands in one or more stories in response to severe ground vibrations. Therefore, in recent years, mechanisms have been presented to distribute inelastic demands over the height of the structure. Strongback braced frame is one of the efforts made in this field. This system, using an elastic truss at the height of the structure, redistributes demands to other floors. In most studies conducted on conventional steel braces, they have been used as energy dissipation elements, while due to the buckling of the braces, adequate energy dissipation is not seen in these structures. In this study, the possibility of improving the behavior of a buckling-restrained braced frame with a crescent-shaped brace was evaluated. Initially, to provide more flexibility in design, a three-part brace or trapezoid brace was introduced, and finally, the possibility of improving the behavior of a strongback braced frame by adding a crescent-shaped or trapezoid brace was evaluated with Nonlinear static analysis. The results showed that the use of a crescent-shaped or trapezoid brace, while improving the energy dissipation of the structure by up to 440.9% and increasing the shear capacity of the structure by up to 57%, did not significantly increase the stiffness of the structure (maximum 14%) and the forces generated in the elastic truss elements formed a uniform distribution over the height of the structure.

کلیدواژه‌ها [English]

  • Crescent-Shaped Brace
  • Trapezoid Brace
  • Strongback Braced Frame
  • Nonlinear Static Analysis
  • Performance Improvement
[1] C.-H. Chen, Performance-based seismic demand assessment of concentrically braced steel frame buildings, University of California, Berkeley, 2010.
[2] S. Kiggins, C.-M. Uang, Reducing residual drift of buckling-restrained braced frames as a dual system, Engineering Structures, 28(11) (2006) 1525-1532.
[3] R. Tremblay, L. Tirca, Behaviour and design of multi-storey zipper concentrically braced steel frames for the mitigation of soft-storey response, in:  STESSA 2003-Behaviour of Steel Structures in Seismic Areas, Routledge, 2018, pp. 471-477.
[4] A. Martin, G.G. Deierlein, Generalized modified modal superposition procedure for seismic design of rocking and pivoting steel spine systems, Journal of Constructional Steel Research, 183 (2021) 106745.
[5] L. Wiebe, C. Christopoulos, R. Tremblay, M. Leclerc, Mechanisms to limit higher mode effects in a controlled rocking steel frame. 1: Concept, modelling, and low‐amplitude shake table testing, Earthquake Engineering & Structural Dynamics, 42(7) (2013) 1053-1068.
[6] B. Qu, F. Sanchez-Zamora, M. Pollino, Transforming Seismic Performance of Deficient Steel Concentrically Braced Frames through Implementation of Rocking Cores, Journal of Structural Engineering, 141(5) (2015) 04014139.
[7] F.C. Blebo, D.A. Roke, Seismic-resistant self-centering rocking core system, Engineering Structures, 101 (2015) 193-204.
[8] T. Takeuchi, X. Chen, R. Matsui, Seismic performance of controlled spine frames with energy-dissipating members, Journal of Constructional Steel Research, 114 (2015) 51-65.
[9] J.-W. Lai, S.A. Mahin, Strongback System: A Way to Reduce Damage Concentration in Steel-Braced Frames, Journal of Structural Engineering, 141(9) (2015) 04014223.
[10] B.G. Simpson, Higher‐mode force response in multi‐story strongback‐braced frames, Earthquake Engineering & Structural Dynamics, 49(14) (2020) 1406-1427.
[11] B.G. Simpson, D. Rivera Torres, Simplified modal pushover analysis to estimate first-and higher-mode force demands for design of strongback-braced frames, Journal of Structural Engineering, 147(12) (2021) 04021196.
[12] M.S. Faramarzi, T. Taghikhany, Direct performance-based seismic design of strongback steel braced systems, in:  Structures, Elsevier, 2020, pp. 482-495.
[13] M.S. Faramarzi, T. Taghikhany, A comparative performance-based seismic assessment of strongback steel braced frames, Journal of Building Engineering, 44 (2021) 102983.
[14] M.D. Symans, M.C. Constantinou, Semi-active control systems for seismic protection of structures: a state-of-the-art review, Engineering Structures, 21(6) (1999) 469-487.
[15] D.R. Sahoo, T. Singhal, S.S. Taraithia, A. Saini, Cyclic behavior of shear-and-flexural yielding metallic dampers, Journal of Constructional Steel Research, 114 (2015) 247-257.
[16] S. A. Mohebi, S. M. Zahrai , R. Raoufi, Seismic evaluation of steel structures retrofitted with supplemental elliptical damper, Amirkabir J. Civil Eng., 55(8) (2023) 1677-1700 (in Persian).
[17] Gh. Pachideh, M. Gholhaki, M. A. Kafi, Experimental and Numerical Evaluation of an Innovative Diamond-Scheme Bracing System Equipped with a Yielding Damper, Amirkabir J. Civil Eng., 53(11) (2022) 4557-4576(in Persian).
[18] B.G. Simpson, S.A. Mahin, Experimental and Numerical Investigation of Strongback Braced Frame System to Mitigate Weak Story Behavior, Journal of Structural Engineering, 144(2) (2018) 04017211.
[19] A. Soleymani, H. Saffari, A novel hybrid strong-back system to improve the seismic performance of steel braced frames, Journal of Building Engineering, 84 (2024) 108482.
[20] T. Trombetti, S. Silvestri, G. Gasparini, I. Ricci, Stiffness-strength-ductility-design approaches for crescent shaped braces, The Open Construction & Building Technology Journal, 3(1) (2009).
[21] M. Palermo, L. Pieraccini, A. Dib, S. Silvestri, T. Trombetti, Experimental tests on Crescent Shaped Braces hysteretic devices, Engineering Structures, 144 (2017) 185-200.
[22] E. Mokhtari, V. Laghi, M. Palermo, S. Silvestri, Quasi-static cyclic tests on a half-scaled two-storey steel frame equipped with Crescent Shaped Braces, Engineering Structures, 232 (2021) 111836.
[23] E. Mokhtari, M. Palermo, V. Laghi, A. Incerti, C. Mazzotti, S. Silvestri, Quasi-static cyclic tests on a half-scaled two-storey steel frame equipped with Crescent Shaped Braces at both storeys: Experimental vs. numerical response, Journal of Building Engineering, 62 (2022) 105371.
[24] M. Palermo, I. Ricci, S. Gagliardi, S. Silvestri, T. Trombetti, G. Gasparini, Multi-performance seismic design through an enhanced first-storey isolation system, Engineering Structures, 59 (2014) 495-506.
[25] M. Palermo, V. Laghi, G. Gasparini, S. Silvestri, T. Trombetti, Analytical estimation of the key performance points of the tensile force-displacement response of Crescent Shaped Braces, Soil Dynamics and Earthquake Engineering, 148 (2021) 106839.
[26] M. Palermo, S. Silvestri, G. Gasparini, T. Trombetti, Crescent shaped braces for the seismic design of building structures, Materials and Structures, 48 (2015) 1485-1502.
[27] S. Mazzoni, OpenSees command language manual, Pacific Earthquake Engineering Research (PEER) Center,  (2006).
[28] J.-W. Lai, Experimental and analytical studies on the seismic behavior of conventional and hybrid braced frames, UC Berkeley, 2012.