‌ارزیابی کاربرد مهاربندهای فولادی همگرا، واگرا و کمانش گریز در بهسازی لرزه ای قاب های خمشی فولادی

نوع مقاله : پژوهشی

نویسندگان

دانشگاه علم و صنعت ایران

چکیده

بسیاری از ساختمان های موجود در کشور براساس ضوابط ویرایش اول استاندارد 2800 طراحی‌ و ساخته شده‌اند. افزایش دانش مهندسی زلزله و اعمال تغییرات در ضوابط آیین نامه های طراحی و ارزیابی لرزه ای در سال های اخیر باعث گردیده است که سازه های موجود در تامین نیازهای لرزه ای دارای ضعف های موضعی یا کلی باشند؛ بنابراین شناسایی و بکارگیری روش های مناسب برای بهسازی لرزه ای سازه های موجود و تامین سطوح عملکرد طراحی سازه ها ضروری است. در این پژوهش، رفتار لرزه ای غیرخطی 6 مدل ساختمان فولادی با سیستم قاب خمشی 4، 8 و 12 طبقه طراحی شده بر اساس ضوابط ویرایش اول استاندارد 2800 و نشریه 519 ، با استفاده از تحلیل استاتیکی غیرخطی بررسی شده است. نتایج ارزیابی نشان می دهد که قاب های خمشی فولادی موجود که بر اساس ویرایش اول استاندارد2800 طراحی و ساخته شده اند نیازهای سختی و شکل‌پذیری ضوابط ویرایش سوم استاندارد 2800 و FEMA356 را تامین نمی‎نمایند و نیازمند بهسازی هستند. بهسازی این قاب ها با مهاربندهای فولادی همگرا باعث افزایش سختی و کاهش تغییر مکان‌های جانبی شده ولی به دلیل کمانش مهاربند فشاری، سازه ها دچار افت ناگهانی مقاومت گردیده و رفتار شکل‌پذیری نداشته اند. در استفاده از مهاربندهای واگرا به علت تمرکز تغییر شکل‌های پلاستیک در تیرهای پیوند و حالت الاستیک مهاربند‌ها رفتار سازه در مقایسه با روش بهسازی با مهاربند های همگرا، دارای شکل‌پذیری بیشتری است. کاربرد مهاربندهای کمانش گریز فولادی به علت عدم کمانش مهاربندهای فشاری و تسلیم در کشش باعث افزایش سختی، مقاومت و شکل‌پذیری سازه نسبت به مهاربندهای همگرا شده است و سطح عمکلرد سازه بهبود یافته است.

کلیدواژه‌ها


عنوان مقاله [English]

Seismic Evaluation of Steel Moment Frames Rehabilitated with CBF, EBF and BRBF Braced Systems

نویسندگان [English]

  • Morteza Raissi Dehkordi
  • Morteza Alizadeh
  • Mahdi Eghbali
چکیده [English]

Many of the existing buildings are made and designed in according to Standard No.2800 (1st Edition). in recent years Increasing in earthquake engineering knowledge and changing in design criteria regulations and seismic evaluation has caused that the existing structures meet local or general deficiencies in seismic requirements. Therefore, the identification and development of appropriate methods is necessary for seismic rehabilitation of existing structures and providing levels of design performance. In this study, the nonlinear seismic behavior of six steel buildings with steel moment frame systems that have modeled in 4, 8 and 12 stories designed according to the criteria of the First Edition 2800 Standard and Publication 519 and has been investigated using nonlinear static analysis. The evaluation results indicate that the existing steel moment frames that are designed according to the Standard No.2800 (1st Edition) can't provide Stiffness and ductility requirements of the Standard No.2800 (3rd Edition) and FEMA356 and must be rehabilitated. The frames Improved by concentrically steel braces, increases stiffness and reduces lateral displacement however, due to buckling of the compression braces, structures suffered a sudden drop in strength and its behavior is not ductile. The use of eccentrically braces due to concentrated plastic deformation in link beams and elastic braces, structural behavior is more ductile in comparison with concentrically braced frames method. The use of buckling restrained braces, due to compressive brace is not buckling and yields in tensile, has caused increase in stiffness, strength and ductility of structure and has improved structural performance in comparison of concentrically braced frames .

کلیدواژه‌ها [English]

  • Seismic evaluation
  • Steel Moment Frames
  • concentrically steel braces
  • eccentrically braces
  • buckling restrained braces
 
[1] Iranian Building Codes and Standards. (1987), “Iranian Code of Practice for Seismic Resistant Design of Buildings, Standard No.2800,” (1st Edition), Building and Housing Research Center, BHRC-PN S253.Tehran, Iran.
[2] Iranian Building Codes and Standards. (2005), “Iranian Code of Practice for Seismic Resistant Design of Buildings, Standard No.2800,” (3rd Edition), Building and Housing Research Center, BHRC-PN S253.Tehran, Iran.
[3]  Council, B. S. S. (2000). Prestandard and commentary for the seismic rehabilitation of buildings, FEMA-356. Federal Emergency Management Agency, Washington, DC.
[4] Seismic, A. I. S. C. (2010). Seismic Provisions for Structural Steel Buildings,(ANSI/AISC 341-10).
[5]  Watanabe, A., Hitomi, Y., Saeki, E., Wada, A., & Fujimoto, M. (1988, August). Properties of brace encased in buckling-restraining concrete and steel tube. InProceedings of Ninth World Conference on Earthquake Engineering (Vol. 4, pp. 719-724).
[6]  Fahnestock, L. A., Sause, R., & Ricles, J. M. (2003). Analytical and experimental studies on buckling restrained braced composite frames. In Proc. of the international workshop on steel and concrete composite construction (pp. 177-88).
[7] Clark, P., Aiken, I., Kasai, K., Ko, E., & Kimura, I. (1999, June). Design procedures for buildings incorporating hysteretic damping devices. In Proceedings 68th annual convention (pp. 355-371).
[8] Inoue, K., Sawaizumi, S., & Higashibata, Y. (2001). Stiffening requirements for unbonded braces encased in concrete panels. Journal of structural engineering, 127(6), 712-719.
[9] Black, C. J., Makris, N., & Aiken, I. D. (2002). Component Testing, Stability Analysis, and Characterization of Buckling-restrained Unbonded Braces (TM). Pacific Earthquake Engineering Research Center.
[10] Tembata, H., Koetaka, Y., & Inoue, K. (2004). Out-of-plane buckling load of buckling-restrained braces including brace joints. Journal of Structural and Construction Engineering, (581), 127-134.
[11] Xie, Q. (2005). State of the art of buckling-restrained braces in Asia. Journal of Constructional Steel Research61(6), 727-748.
[12] Takeuchi, T., Suzuki, K., Marukawa, T., Kimura, Y., Ogawa, T., Sugiyama, T., & Kato, S. (2005). Performance of compressive tube members with buckling restrained composed of mortar in-filled steel tube. Journal of Structure and Construction Engineering, AIJ590, 71-8.
[13] Clark, P., Aiken, I., Kasai, K., Ko, E., & Kimura, I. (1999, June). Design procedures for buildings incorporating hysteretic damping devices. In Proceedings 68th annual convention (pp. 355-371).
 [14]  W. B. Ma N, Zhao JX, Li H, Ou JP, Yang WB. , (2008, October), Full scale test of all-steel buckling restrained braces, In Proceeding of the 14th World Conference on Earthquake Engineering, Beijing, China.
[15]  Zhao, J., Wu, B., & Ou, J. (2014). A practical and unified global stability design method of buckling-restrained braces: Discussion on pinned connections. Journal of Constructional Steel Research, 95, 106-115.
[16]  Bozorgnia, Y., & Bertero, V. V. (Eds.). (2004). Earthquake engineering: from engineering seismology to performance-based engineering. CRC press.
[17] Zhao, J., Wu, B., & Ou, J. (2011). A novel type of angle steel buckling‐restrained brace: Cyclic behavior and failure mechanism. Earthquake Engineering & Structural Dynamics40(10), 1083-1102.
[18] Office of Deputy for Strategic Supervision, Bureau of Technical Execution, System, “Commentary of Instruction for seismic Rehabilitation of Existing Buildings”, (2009), NO: 361, Islamic Republic of Iran, Vice Presidency for Strategic Planning and Supervision, Tehran.
[19] American Society of Civil Engineers & Structural Engineering Institute, (2010), Minimum Design Loads for Buildings and Other Structures, ASCE Standard ASCE/SEI 7-10, ASCE Publications.
[20] ASCE/SEI Seismic Rehabilitation Standards Committee, (2007), “Seismic Rehabilitation of Existing Buildings (ASCE/SEI 41-06), American Society of Civil Engineers, Reston, VA, US.
[21] Nippon Steel Engineering Unbonded Brace Design Information Packet (2006)
[22] Burkholder, M. C. (2012). Performance Based Analysis of a Steel Braced Frame Building With Buckling Restrained Braces.
 [23]  López, W. A., Gwie, D. S., Saunders, M., & Lauck, T. W. (2002). Lessons learned from large-scale tests of unbonded braced frame subassemblage. In Proc. 71st Annual Convention of SEAOC (pp. 171-183).
[24]  Sanaei, A,M.,. (2012). Seismic Analysis of  Plan Irregular Structures, In Proc. 9th International Congress on Civil Engineering.
 [25] Alizadeh, M.,(2013). Evaluation and Comparison the Seismic Behavior of Rehabilitation Steel Structures with CBF, EBF and BRBF Braced Systems. M.Sc. Thesis, Iran University of Science and Technology.