ارزیابی تأثیر فاصله آزاد انتهایی و استفاده از سخت‌کننده‌ها در صفحه اتصال بر عملکرد فشاری مهاربندهای قطری

نوع مقاله: علمی - پژوهشی

نویسندگان

1 دانشیار، دانشکده مهندسی عمران، دانشگاه تربیت دبیر شهید رجایی، تهران، ایران

2 کارشناسی ارشد مهندسی عمران سازه، دانشگاه تربیت دبیر شهید رجایی، تهران، ایران

3 کارشناس ارشد مهندسی عمران سازه، دانشگاه تربیت دبیر شهید رجایی، تهران، ایران

چکیده

اعضای مهاربندهای قطری باید بتوانند نیروی فشاری قابل توجهی را تحمل کنند. اتصال این اعضا به تیر و ستون نقش مهمی در مقدار این نیرو دارد. این اتصال به گونه‏ای طراحی می‏شود که با کمانش آزادانه عضو، مشکلی برای اتصال کناری بوجود نیاورد و یا با تقویت صفحه اتصال از خسارات ناشی از کمانش احتمالی عضو در محل اتصال صفحه جلوگیری نماید. برای ارزیابی رفتار لرزه‏ای و کمانشی مهاربندها در حالت‏های مختلف، 5 قاب یک طبقه تک دهانه با مهاربند قطری در نرم‌افزار المان محدود آباکوس بررسی شده است. ابتدا با استفاده از آنالیز کمانش به بررسی بار بحرانی عضو مهاربندی و به تبعیت از آن ضریب طول مؤثر مهاربند پرداخته شده‌است، سپس با در نظر گرفتن نقص اولیه براساس آنالیز کمانش، نمونه ها تحت آنالیز غیرخطی پس‌کمانش قرار گرفته و نتایج حاصل از منحنی‌های برش پایه- تغییرمکان، تنش و کرنش نمونه‌ها با یکدیگر مقایسه شده‌است. در 2 مدل اول اثرات محل انقطاع مهاربند و در 3 مدل دیگر اثرات استفاده از انواع سخت‌کننده‌ها در ورق اتصال مورد ارزیابی قرارگرفته است. نتایج بیانگر افزایش شکل‌پذیری قاب در اثر رعایت فاصله آزاد توصیه شده توسط آیین‌نامه‌های معتبر ساختمانی و جلوگیری از خرابی پیش از موعد اتصال ورق گوشه در اثر استفاده صحیح از سخت‌کننده‌ها است.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Evaluation of end clearance and using stiffeners on gusset plate effect on the compressive performance of diagonal bracing systems

نویسندگان [English]

  • Mussa Mahmoudi Sahebi 1
  • Arash Zarezadeh 2
  • Aliraza Shirpour 3
1 Associate professor, Department of Civil Engineering, Shahid Rajaee Teacher Training University, Tehran, Iran
2 Master of civil engineering, Faculty of Civil Engineering, Shahid Rajaee Teacher Training University, Tehran, Iran
3 Master of civil engineering, Faculty of Civil Engineering, Shahid Rajaee Teacher Training University, Tehran, Iran
چکیده [English]

The braced frame is used in steel structures to confront lateral loads. In Iran, braced frames, especially concentrically braced frames are more commonly used due to their high levels of rigidity and ease and speed of construction. The bracing member of this system bears considerable amounts of load, and thus it needs to be properly connected to the main frame members to display a satisfactory performance. Gusset plates are used to implement such connections. Due to the need for ductility of concentrically braced frames, researchers have conducted extensive research on factors influencing ductility of these structures and especially their connections. The brace end clearance is one of the factors influencing this parameter. It is also possible to influence the connection and frame performances by using stiffeners on gusset plates. This connection is designed to either prevent problems caused to the end-connection through free buckling of a member or reinforcing the gusset plate to reduce damages caused by possible buckling of a member at the connection location. In this research, 5 one-span one-story frames with diagonal braces were modeled in ABAQUS finite element method software. The effects of brace end clearance and effects of stiffeners on gusset plates were studied in the first 2 models and the other 3 models, respectively. First, a buckling analysis was carried out to study brace critical load and the brace effective length coefficient. Afterwards, considering the initial imperfection determined by buckling analysis, the samples were exposed to post-buckling nonlinear analysis and results of the base shear-displacement and stress-strain curves were compared. Comparison results revealed that by considering the brace end clearance recommended by reputable building codes it is possible to increase ductility and prevent early failure of corner joint plates. Proper use of stiffeners also may improve performance of lateral connections and the braced frame.

کلیدواژه‌ها [English]

  • Gusset plate stiffener
  • End-connection
  • Effective length coefficient
  • Diagonal bracing
  • End clearance

[1] Azhari, M. and Mirghaderi, R. (2014). Limit states design of steel structures (LRFD). Vol. 5, 3th ed, Esfahan: Arkane Danesh.

[2] Roghani, M. (2002). Linear and nonlinear analysis of moment frame and CBF systems in order to evaluate their performance. M.s, the University of Yazd.

[3] AISC 360-10. (2010). Seismic provisions for structure steel building. American institute of steel construction, Chicago, IL, USA.

[4] Whitmore, Richard E. (1952). Experimental Investigation of Stresses in Gusset Plates. Engineering Experiment Station, University of Tennessee, Knoxville.

[5] Thornton, William A. (1984). Bracing Connections for Heavy Construction. Engineering Journal, AISC 21(3): 139–48.

[6] Bjorhovde, R. and Chakrabarti, S. K. (1985). Tests of full-size Gusset plate connections. Journal of Structural Engineering, American society of civil engineers, 111(3): 667-683.

[7] Bjorhovde, R. (1988). Limit states design considerations for Gusset plates.  Journal of Constructed Steel Research, 9: 61-73.

[8] Astaneh-Asl, A., Goel, S. C. and Hanson, R. D. (1985). Cyclic out-of-Plane Buckling of Double-Angle Bracing. Journal of structural Engineering, 111(5): 1135–53.

[9] Astaneh-Asl, A., Goel, S. C. and Hanson, R. D. (1986). Earthquake-Resistant Design of Double-Angle Bracings. Engineering Journal, 23(4).

[10] Lehman, D. and Roeder, C. (2008). Improved seismic design of concentrically braced frames and gusset plate connections. ASCE, Structures Congress, pp. 1-10.

[11] Lehman, D. E., Roeder, C., Herman, D., Johnson, S. and Kotulka, B. (2007). Improved seismic performance of Gusset plate connections. ASCE, Journal of Structural Engineering, Reston, VA.

[12] Wijesundara, K. K, Rassathi, G. A., Nascimbene, R. and Bolognini, D. (2010). Seismic performance of brace-beam-column connections in concentrically breced frames. ASCE, Structures Congress, pp. 930-942.

[13] Chen, S. J. and Chang C. C. (2012). Experimental Study of Low Yield Point Steel Gusset Plate Connections. Thin-Walled Structures, 57: 62–69.

[14] Sheng, N., Yam, C. H. and Lu, V. P.  (2002). Analytical Investigation and the Design of the Compressive Strength of Steel Gusset Plate Connections. Journal of Constructional Steel Research, 58(11): 1473–93.

[15] Simulia, D S. (2013). Dassault Systems, Providence, RI ABAQUS 6.13 User’s Manual. Dassault Systems, Providence, RI.

[16] Eurocode 3: Design of Steel Structure – Part 1-1: General Rules and Rules for Building. EN 1993-1-1 (2005).

[17] Alipour, M. and Aghakouchak, A. (2013). Numerical analysis of the nonlinear performance of concentrically braced frames under cyclic loading. International Journal of Steel Structures, 13(3): 401-419.

[18] Yoo, J. H., Lehman, D. E. Roeder, C. W. (2007). Influence of Connection Design Prameters on the Seismic Performance of Braced Frames. Journal of Constructional Steel Research, 64(6): 607-623.

[19] Yoo, J. H., Roeder, C. W. and Lehman, D. E. (2008). Analytical performance simulation of special concentrically braced frames. Journal of Structural Engineering, pp. 881-889.

[20] Shahbazi, R. Yekrangnia, M. (2014). Abaqus applied manual with examples for civil engineering, 2th ed, Tehran: Elme Omran.

[21] Alipour, M. and Aghakouchak, A. A. (2013). The effect brace end clearance on ductility of concentrically braced frame. Amirkabir Journal of Science and Research, Civil and environmental engineering, 45(1): 1-12