تاثیر درجات آزادی بر ضریب رفتار قاب‌های خمشی بتن آرمه دارای دیوار برشی فولادی نازک

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشگاه سمنان

2 عضو هیات علمی دانشگاه سمنان

چکیده

ضریب رفتار در اثر شکل‌پذیری (Rμ)، مقاومت جانبی سازه یکدرجه آزادی (SDOF) را طوری تنظیم می‌کند که نیاز شکل‌پذیری به یک مقدار شکل‌پذیری هدف معین محدود گردد. روش‌های موجود در آیین‌نامه‌های لرزه‌ای جهت محاسبه ضریب رفتار سازه چند درجه آزادی (MDOF) به نحوی پایه ریزی شده است که در راستای کاهش اثر ورود نیروی برش پایه به ناحیه غیرالاستیک، از نتایج Rμ استفاده گردد. این درحالی است که اثرات مدلسازی سازه به صورت MDOF می‌تواند بر ضریب رفتار سازه MDOF اثر داشته و به کمک Rμ نیازمند اصلاحاتی می‌باشد. به همین دلیل در این پژوهش دو ضریب کاهش مقاومت در اثر شکل‌پذیری (Rμ) و نسبت تغییرشکل غیرالاستیک به الاستیک (CR) در سازه SDOF برای مؤلفه‌های موازی و عمود برگسل زلزله حوزه نزدیک و دور از گسل محاسبه شده‌اند. همچنین CR بدست آمده با ضریب اصلاحی C1 پیشنهادی FEMA440 مقایسه و ضریب بزرگنمایی تغییرمکان به ضریب رفتار برای سطوح مختلف شکل‌پذیری محاسبه شده است. در پایان این پژوهش پس از بررسی اثرات غیر خطی سازه‌ی SDOF از طریق ضرایب Rμ پرداخته و با احتساب اثر مودهای بالاتر، این ضرائب را برای سازه‌های MDOF اصلاح می‌نماییم و رابطه‌ای برای محاسبه آن پیشنهاد می‌گردد. نتایج بدست آمده نشان داد که Rμ ناشی از زلزله حوزه نزدیک می‌تواند با مقدار متناظر حاصل از زلزله دور تفاوت داشته باشد. همچنین CR چندان به نوع رکورد وابسته نبوده و با افزایش دوره تناوب اصلی سازه به یک همگرا می‌شود. همچنین ضریب اصلاحی با افزایش دوره تناوب اصلی سازه و افزایش تقاضای شکل‌پذیری، افزایش می‌یابد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Effects of Freedom Degrees on Behavior Factor in Reinforced Concrete Moment Resisting Frames with Steel Plate Shear Wall

نویسندگان [English]

  • seyyed reza salim bahrami 1
  • majid gholhaki 2
1 Semnan university
چکیده [English]

The influence of the strength reduction factor due to nonlinear behavior (Rμ) on the lateral strength of Single-Degree-Of-Freedom (SDOF) structures causes to limit the displacement ductility demand to the predetermined maximum tolerable ductility. In addition, Rμ is used for determining the behavior factor in Multi-Degree-Of-Freedom (MDOF) structures. Following this, in this paper, Rμ and the inelastic displacement ratio (CR) for equivalent SDOF systems under strike[1]parallel (NF-SP) and strike-normal (NF-SN) components of near-field ground motion, and also far[1]field (FF) ground motion were assessed. Furthermore, CR obtained by this study was compared with C1 proposed by FEMA440. The deflection amplification factor-to-behavior factor ratio (Cd/Ru) for different ductility levels was computed. After evaluating the nonlinear effects of SDOF structures based on Rμ factors, these factors for MDOF structure were modified considering higher mode effects, and a simplified practical expression was proposed to estimate the base shear modification factor. The results indicated that Rμ, corresponds to near and far-field ground motions can be different. In addition, CR does not depend on the type of earthquake, and it converges to 1 by increasing the period of vibration. In addition, the modification factor can be increased with period and ductility demand.

کلیدواژه‌ها [English]

  • Behavior factor
  • Modification Factor
  • SDOF Structure
  • MDOF
  • Base Shear
[1] N.M. Newmark, W.J. Hall, Procedures and criteria for earthquake-resistant design, in: Selected Papers By Nathan M. Newmark: Civil Engineering Classics, ASCE, 1973, pp. 872-829.
[2] A.A. Nassar, H. Krawinkler, Seismic Demand for SDOF and MDOF Systems, in, Stanford University, Stanford, 1991.
[3] E. Miranda, Site-dependent strength-reduction factors, Journal of Structural Engineering, 3519-3503 (1993) 119.
[4] G. Seneviratna, H. Krawinkler, Evaluation of Inelastic MDOF Effects for Seismic Design, in, Stanford, California, 1997.
[5] A. FEMA, 440, Improvement of nonlinear static seismic analysis procedures, FEMA440-, Redwood City, (2005).
[6] I.S. Code, Iranian code of practice for seismic resistant design of buildings 2014) ,(2014) 2800).
[7] R.S. Jalali, M.D. Trifunac, STRENGTH-REDUCTION FACTORS FOR STRUCTURES SUBJECTED TO NEAR-SOURCE DIFFERENTIAL STRONG GROUND MOTIONS, ISET JOURNAL OF EARTHQUAKE TECHNOLOGY,  285.
[8] M. Izadinia, M.A. Rahgozar, O. Mohammadrezaei, Response modification factor for steel moment-resisting frames by different pushover analysis methods, Journal of Constructional Steel Research, 90-83 (2012) 79.
[9] A.K. Chopra, C. Chintanapakdee, Inelastic deformation ratios for design and evaluation of structures: singledegree-of-freedom bilinear systems, Journal of structural engineering, 1319-1309 (2004) 130.
[10] J. Ruiz‐García, E. Miranda, Inelastic displacement ratios for evaluation of existing structures, Earthquake Engineering & Structural Dynamics, 1258-1237 (2003) 32.
[11] S.M. Parsaeian, H. Hashemi, A.R. Sarvghad Moghadam, Inelastic Displacement Ratios for Structures on Firm Soil Sites Subjected to Iran Earthquakes Records, Modares Civil Engineering journal, 25-11 (2013) 12.
[12] W.-P. Wen, C.-H. Zhai, S. Li, Z. Chang, L.-L. Xie, Constant damage inelastic displacement ratios for the near-fault pulse-like ground motions, Engineering Structures, 59 607-599 (2014).
[13] C.-H. Zhai, W.-P. Wen, T.-T. Zhu, S. Li, L.-L. Xie, Inelastic displacement ratios for design of structures with constant damage performance, Engineering Structures, (2013) 52 63-53.
[14] M. Gerami, N. Siahpolo, R. Vahdani, Effects of higher modes and MDOF on strength reduction factor of elastoplastic structures under far and near-fault ground motions, Ain Shams Engineering Journal, 143-127 (2017) 8.
[15] G.S. SABOURI, H.M. GHOL, Ductility of thin steel plate shear walls, (2008).
[16] S. Sabouri-Ghomi, S. Mamazizi, M. Alavi, An Investigation into Linear and Nonlinear Behavior of Stiffened Steel Plate Shear Panels with Two Openings, Advances in Structural Engineering, 700-687 (2015) 18.
[17] I.-R. Choi, H.-G. Park, Cyclic loading test for reinforced concrete frame with thin steel infill plate, Journal of Structural Engineering, 664-654 (2010) 137.
[18] D.J. Borello, L.A. Fahnestock, Large-Scale Cyclic Testing of Steel-Plate Shear Walls with Coupling, Journal of Structural Engineering, 4017133 (2017) 143.
[19] L. Jiang, H. Zheng, Y. Hu, Experimental seismic performance of steel-and composite steel-panel wall strengthened steel frames, Archives of Civil and Mechanical Engineering, 534-520 (2017) 17.
[20] M.H. Asl, M. Safarkhani, Seismic behavior of steel plate shear wall with reduced boundary beam section, ThinWalled Structures, 179-169 (2017) 116.
[21] M. Wang, W. Yang, Equivalent constitutive model of steel plate shear wall structures, Thin-Walled Structures, 124 .)8102( 514-924
[22] S.R. Salimbahrami, M. Gholhaki, Analytical study to evaluate the effect of higher modes of reinforced concrete moment-resisting frames with thin steel shear wall under simple pulse, Advances in Structural Engineering, ((2018 .1423778123349631
[23] H.-G. Park, J.-H. Kwack, S.-W. Jeon, W.-K. Kim, I.-R. Choi, Framed steel plate wall behavior under cyclic lateral loading, Journal of structural engineering, (2007) 133 .873-883
[24] L.J. Thorburn, G.L. Kulak, C.J. Montgomery, Analysis of steel plate shear walls, in: Structural engineering report no.107, Edmonton, AB, Canada, 1983.
[25] I.N.B. Code, Applied Loads on Buildings, Part 2013) ,6).
[26] A.I.o.S.C. (AISC), Specification for Structural Steel Buildings (ANSI/AISC 2010) ,(16-360).
[27] A.C.I. Committee, A.C. Institute, I.O.f. Standardization, Building code requirements for structural concrete (ACI 08-318) and commentary, in, American Concrete Institute, 2008.
[28] A.S.C. Engineers, Minimum Design Loads for Buildings and Other Structures: Second Printing, (2010).
[29]  I.N.B. Code, Design and Implement of Concrete Buildings, Part 2013) ,9).
[30] I.N.B. Code, Design and Implement of Steel Buildings, Part 2013) ,10).
[31] J.W. Baker, Quantitative classification of near-fault ground motions using wavelet analysis, Bulletin of the Seismological Society of America, 1501-1486 (2007) 97.
[32] N.M. Newmark, A method of computation for structural dynamics, Journal of the engineering mechanics division, 94-67 (1959) (3)85.
[33] C.-M. Uang, Establishing R (or R w) and C d factors for building seismic provisions, Journal of structural Engineering, 28-19 (1991) 117.
[34] L.H. Najafi, M. Tehranizadeh, H. Ave, Evaluation of seismic behavior for moment frames and eccentrically braced frames due to near-field ground motions, ASIAN JOURNAL OF CIVIL ENGINEERING (BHRC), 14( 2013).
[35] C.-M. Uang, A. Maarouf, U.S.C.U.S.E. Consortium, Safety and economic considerations of UBC seismic force reduction factors, in: < 1993= Mil novecientos noventa y tres> National Earthquake Conference: Earthquake Hazard Reduction in the Central and Eastern United States: A Time for Examination and Action, US Central United States Earthquake Consortium (CUSEC), 1993, pp. 130-121.
[36] F. FEMA273, FEMA356, NEHRP guidelines for the seismic rehabilitation of buildings, Washington DC: Federal Emergency Management Agency, (1996).
[37] B.S.S. Council, Prestandard and commentary for the seismic rehabilitation of buildings, Report FEMA356-, Washington, DC, (2000).
[38] M.-H. Peng, F. Elghadamsi, B. Mohraz, A stochastic procedure for nonlinear response spectra, in: Ninth Wld Conf. Earthq. Eng, 1988, pp. 1074-1069.