عملکرد اتصال پیچی لینک به دستک در قاب های خمشی درختی تحت اثر آتش سوزی

نوع مقاله : علمی - پژوهشی

نویسندگان

1 دانشیار، دانشکده مهندسی عمران، دانشگاه صنعتی خواجه نصیرالدین طوسی

2 دانشجوی دکتری مهندسی سازه، دانشکده مهندسی عمران، دانشگاه صنعتی خواجه نصیرالدین طوسی

چکیده

یکی از سیستم‌های سازه‌ای کارآمد در ساختمان‌های فولادی، قاب‌های خمشی درختی با اتصالات پیچی می‌باشند که در سال‌های اخیر به میزان وسیعی مورد استفاده قرار گرفته‌اند. تحقیقات بسیار اندکی بر روی رفتار این سیستم در شرایط آتش‌سوزی صورت گرفته است. این مقاله به بررسی آزمایشگاهی رفتار تیر و اتصالات وصله‌ای پیچی در قاب‌های خمشی درختی تحت اثر آتش می‌پردازد. بدین ‌منظور دو قاب فولادی با اتصالات متفاوت در مقیاس واقعی تحت اثر آتش استاندارد ایزو 834 آزمایش گردید. رفتارهای سازه‌ای و حرارتی نمونه‌ها در آتش، شامل تاریخچه دماها، نمودارهای دما - خیز و زمان - خیز تیر، دما - دوران اتصال و مودهای خرابی مطالعه شده است. مشاهده گردید که اتصال تیر میانی به دستک به علت گسیختگی برشی پیچ‌های وصله بال بالایی در دمای بالاتر از C°750 دچار خرابی می‌گردد و این درحالیست که تیر خیزهای بزرگی بیش از یک بیستم دهانه را تجربه می‌نماید. همچنین استفاده از ورق‌های دوبل با پیچ‌های دوبرشه در وصله بال می‌تواند باعث بهبود تاب حرارتی و ظرفیت دورانی اتصالات وصله‌ای پیچی تیر شود.

کلیدواژه‌ها


عنوان مقاله [English]

Performance of Link-To-Stub Bolted Connection in Column-Tree Moment Resisting Frames under Fire Conditions

نویسندگان [English]

  • Mahmood Yahyai 1
  • Abbas Rezaeian 2
1 Associate Professor,Department of Civil Engineering, K.N. Toosi University of Technology
2 PhD Scholar of Structural Engineering, Department of Civil Engineering, K.N. Toosi University of Technology
چکیده [English]

Column-tree moment resisting frames, as the efficient shop-welded and field-bolted structural systems, are used in many countries. Very limited research has been carried out on such systems under fire conditions. This paper presents experimental investigations of the behavior of beam and bolted splice connections in steel column-tree moment resisting frames exposed to fire. Two full-scale steel sub-frames with different splice connections were tested under ISO 834 standard fire. The flange splice plates were configured as a single plate with single shear bolts in first specimen, and as double plates with double shear bolts in second specimen. The observation of thermal and structural fire behaviors including temperature histories, temperature-deflection of the beam, temperature-rotation of splice connections and failure modes were investigated. The temperature-deflection and temperature-rotation curves remained in the elastic range until about 600°C. Beyond 600°C, the behavior would be highly nonlinear plastic. The beam splice connection failed due to shear fracture of top bolts at temperatures beyond 750°C. Consequently, stub beam web failed at those temperatures because of block-shear. Using double plates with double shear bolts for flange splices would enhance the temperature resistance and rotational capacity of the beam splice connections. Both tests results confirmed that specimens retain the capacity to support the design load when the average beam temperature does not exceed 600°C. This temperature limit confirms the temperature criteria provided by ASTM E119 and ANSI/UL 263 for a restrained beam, and can be used to specify the minimum fire resistance criteria for beams in column-tree MRFs. The measured time-deflection curves showed that the restrained fire resistance rating for both unprotected specimens obtained about 15 minutes in both tests.

کلیدواژه‌ها [English]

  • experimental study
  • steel beam
  • Bolted connection
  • Failure modes
  • Fire
[1] Franssen, J. M.; Kodur, V. and Zaharia, R. “Designing steel structures for fire safety”, Taylor & Francis Group, London, UK (2009).
[2] CEN. EN 1993-1-2, “Eurocode 3: Design of steel structures”, Part 1.2: general rules-structural fire design”, British Standards Institution, London (2005).
[3] AISC “Specification for structural steel buildings 360–10”, American Institute of Steel Construction Inc, Chicago (2010).
[4] Al-Jabri, K. S.; Burgess, I.W.; Lennon, T. and  Plank, R.J. “Moment-rotation-temperature curves for semi-rigid joint”, J. Constr. Steel Res., 61, pp. 281-303 (2005).
[5] Saedi Daryan, A. and Yahyai, M. “Behavior of bolted top-seat angle connections in fire”, J. Constr. Steel Res., 65, pp. 531–541 (2009).
[6] Saedi Daryan, A. and Yahyai, M. “Behavior of welded top-seat angle connections exposed to fire”, Fire Saf. J., 44, pp. 603-611 (2009).
[7] Wald, F.; Simoes da Silva, L.; Moore, D.B.; Lennon, T.; Chladna, M.; Santiago, A. and et al. “Experimental behavior of a steel structure under natural fire”, Fire Saf. J., 41, pp. 509–522 (2006).
[8] Liu, T.C.H.; Fahad, M.K. and Davies, J.M. “Experimental investigation of behavior of axially restrained steel beams in fire”, J. Constr. Steel Res., 58, pp. 1211–1230 (2002).
[9] Li, G.Q. and Guo, S.X. “Experiment on restrained steel beams subjected to heating and cooling”, J. Constr. Steel Res., 64, pp. 268–274 (2008).
[10] Santiago, A.; Simoes da Silva, L.; Vaz, G.; Vila Real, P. and Gameiro Lopes, A. “Experimental investigation of the behavior of a steel sub-frame under a natural fire”, Steel Compos. Struct., 8, pp. 243-264 (2008).
[11] Ding, J. and Wang, Y.C. “Experimental study of structural fire behavior of steel beam to concrete filled tubular column assemblies with different types of joints”, Eng. Struct., 29, pp. 3485–3502 (2007).
[12] Wang, Y.C., Dai, X.H. and Bailey, C.G. “An experimental study of relative structural fire behavior and robustness of different types of steel joint in restrained steel frames”, J. Constr. Steel Res., 67, pp. 1149-1163 (2011).
[13] Saedi Daryan A, Yahyai M. “ Modeling of bolted angle connections in fire”, Fire Saf. J., 44, pp. 976-988 (2009).
[14] Yahyai, M. and Saedi Daryan, A. “The study of welded semi-rigid connections in fire”, Struct. Design Tall Spec. Build. (2011).
[15] Astaneh-Asl, A. “Seismic design of steel column-tree moment-resisting frames”, Structural Steel Educational Council, Berkeley, CA (1997).
[16]FEMA 403, “World Trade Center building performance study: Data collection, preliminary observations, and recommendations”, Federal Emergency Management Agency, Washington, DC (2002).
[17] LaMalva, K.J.; Barnett, J.R. and Dusenberry, D.O. “Failure analysis of the World Trade Center 5 building”, J. Fire Protection Eng., 19, pp. 261-274 (2009).
[18] ISO 834, “Fire resistance test-Elements of building construction”, International Organization for Standardization, Geneva (1999).
[19] BS 476-20, Fire tests on building materials and structure-Part 20: “Method for determination of the fire resistance of elements of construction”. European Committee for Standardization (CEN), Brussels (1987).
[20] ASTM Standard E119-05 “Standard methods of fire tests of building construction and materials”, American Society for Testing and Materials, West Conshohocken, PA, 2005
[21] UL 263, “Fire Tests of Building Construction and Materials”,. Underwriters Laboratories Inc, Northbrook, Illinois, 2003
[22] IBC. “ International Building Code”, 2006 Edition, International Code Council, Country Club Hills, IL, 2006.
[23] NFPA, “Building Construction and Safety Code, NFPA 5000”. National Fire Protection Association, Quincy, MA. (2003)