ارزیابی احتمالاتی دریفت پسماند در سازه‌های خمشی فولادی با میراگرهای ویسکوز خطی و غیرخطی

نوع مقاله : مقاله پژوهشی

نویسندگان

گروه مهندسی عمران، دانشکده فنی و مهندسی، دانشگاه بین‌المللی امام خمینی (ره)، قزوین، ایران

چکیده

مقدار تغییر مکان‌های پسماند مهم‌ترین عامل تصمیم‏گیری در مورد ایمنی و اقتصادی بودن بهسازی سازه­ها یا ساخت دوباره آنها بعد از زلزله است. در این مطالعه اثرات استفاده از میراگر­های ویسکوز خطی و غیرخطی و نحوه توزیع ضرایب میرایی متناظر با آنها بر روی پاسخ دریفت پسماند سازه­های با سیستم قاب خمشی ویژه مجهز شده به میراگر­های ویسکوز مورد بررسی قرار گرفت. بر این اساس، مقادیر ظرفیت متناظر با سطوح مختلف دریفت پسماند        بین­طبقه­ای سازه­ها با استفاده از تحلیل‏های دینامیکی افزاینده (IDA) محاسبه شد. پس از آن، مقادیر میانگین فراوانی سالیانه عبور از حدود مختلف دریفت پسماند (RDλ) محاسبه شد. نتایج به‌دست‌آمده نشان داد که مقادیر RDλ برای سازه­های با میراگر­های ویسکوز خطی بین 87/6 تا 24/80 درصد کمتر از مقادیر RDλ برای ساز­ه‏های با میراگرهای ویسکوز غیرخطی متناظر با آنهاست. همچنین بررسی‏های انجام شده بر روی اثر نحوه توزیع ضرایب میرایی در ارتفاع نشان داد که با وجود طبقه نرم در سازه، عملکرد سازه­های دارای توزیع ضرایب میرایی در ارتفاع متناسب با دریفت بین­طبقه­ای متناظر با شکل مود اول سازه (IDPD) نسبت به سازه­های دارای توزیع ضرایب میرایی به‌صورت یکنواخت از لحاظ کمتر بودن مقدار RDλ بهتر است.

کلیدواژه‌ها


عنوان مقاله [English]

Probabilistic Evaluation of Residual Drift Demands in Steel Moment Resisting Frames Equipped with Linear and Nonlinear Fluid Viscous Dampers

نویسندگان [English]

  • Ali Yahyazadeh
  • Mansoor Yakhchalian
Department of Civil Engineering, Faculty of Engineering and Technology, Imam Khomeini International University, Qazvin, Iran
چکیده [English]

Maximum interstory drift ratio is a useful engineering demand parameter for predicting damage and structural collapse. In recent decades, some research studies have focused on Maximum Residual Interstory Drift Ratio (MRIDR) of structures as another engineering demand parameter. MRIDR plays a key role in assessing the seismic performance of structure after seismic events, because it indicates that if structure is safe or not, and if the repair of structure is economical or not. Nowadays, passive control systems are employed for designing new structures and improving the seismic performance of existing structures. Among them, the use of Fluid Viscous Dampers (FVDs) has become very common because of their remarkable energy dissipation capacity, negligible maintenance cost and the possibility of being used in multiple earthquakes. Linear FVDs have a velocity exponent of α=1.0 and nonlinear FVDs have velocity exponents of α≠1.0. This study evaluates the effects of employing linear and nonlinear FVDs and different vertical distributions of damping coefficients on the MRIDR response of steel Special Moment Resisting Frames (SMRFs) with FVDs. For this purpose, low- and mid-rise steel SMRFs including the 3- and 9-story SMRFs designed for Los Angeles as part of SAC steel project are considered. Moreover, the height of the first story in the 3-story SMRF is increased by a factor of 1.4 to generate a 3-story SMRF with a soft story. Each of these three structures is equipped with FVDs to limit maximum interstory drift ratio under the design earthquake to 0.015. Two types of vertical distributions of damping coefficients that include uniform distribution and Interstorey Drift Proportional Distribution determined on the basis of the first mode deformations (IDPD) are assumed for each of the structures. Moreover, four values of α=0.25, 0.5, 0.75 and 1.0 are considered for FVDs. OpenSees software is applied to model the structures. Concentrated plasticity approach is used for modeling beams. In this approach, each beam is modeled by an elastic beam-column element and two zero-length elements simulating inelastic response. However, columns are modeled using nonlinear beam-column elements, which are based on the concept of distributed plasticity. The P-Delta effects of gravity columns are accounted for by a leaning column. Four MRIDR values of 0.002, 0.005, 0.01 and 0.02 are assumed as limit states, and Incremental Dynamic analyses (IDAs) are performed on the structures using a set of far-field ground motion records considering each of these limit states. For performing the IDAs, 5% damped pseudo spectral acceleration at the fundamental period of structure, Sa(T1), is selected as ground motion intensity measure. Using the results of the IDAs median MRIDR capacity, i.e., median SaRD, and its corresponding logarithmic standard deviation are calculated for each of the structures. Then, assuming lognormal distribution for SaRD, residual drift fragility curves are obtained for the structures given each of the MRIDR limit states. The results indicate that given each of these limit states, the structure equipped with linear FVDs has higher median SaRD compared with its corresponding structure equipped with nonlinear FVDs. Furthermore, reducing α causes reduction in median SaRD. Residual drift fragility curves corresponding to all the limit states for each of the structures are combined with the seismic hazard curve for the site assumed to calculate the mean annual frequencies of exceeding these MRIDR limit states (λRD). According to the results, the values of λRD for the structures with linear FVDs are between 6.87% to 80.24% lower than those for the structures with nonlinear FVDs. Comparing the results obtained using the two height-wise distributions of damping coefficients shows that when first story height is greater than typical story height, using IDPD leads to higher median SaRD and lower λRD.

کلیدواژه‌ها [English]

  • Fluid Viscous Damper
  • Maximum Residual Interstory Drift Ratio
  • Incremental Dynamic Analysis
  • Vertical Distribution of Damping Coefficients
1.    Rosenblueth, E. and Meli, R. (1986) The 1985 Mexico earthquake. Concrete International, 8(5), 23-34.‏‏
2.    Ruiz-Garcia, J. and Miranda, E. (2008) Probabilistic seismic assessment of residual drift demands in existing   buildings. Proc. 14th World Conference on Earthquake Engineering.
3.    Bojórquez, E. and Ruiz‐García, J. (2013) Residual drift demands in moment‐resisting steel frames subjected to narrow‐band earthquake ground motions. Earthquake Engineering and Structural Dynamics, 42(11), 1583-1598.‏
4.    Soong, T.T. and Spencer, B.F. (2002) Supplemental energy dissipation: state-of-the-art and state-of-the-practice. Engineering Structures, 24(3), 243-259.
5.    Seleemah, A.A. and Constantinou, M.C. (1997) Investigation of Seismic Response of Buildings with Linear and Nonlinear Fluid Viscous Dampers. Buffalo, NY: National Center for Earthquake Engineering Research.
6.    Constantinou, M.C. and Symans, M.D. (1992) Experimental and Analytical Investigation of Seismic Response of Structures with Supplemental Fluid Viscous Dampers. Buffalo, NY: National Center for Earthquake Engineering Research.‏
7.    Bahnasy, A. and Lavan, O. (2013) Linear or nonlinear fluid viscous dampers? A seismic point of view. Proc. International Structures Congress 2013: Bridging Your Passion with Your Profession, pp. 2253-2264.‏
8.    Cornell, C.A. and Krawinkler, H. (2000) Progress and Challenges in Seismic Performance Assessment. PEER center news, 3.
9.    Krawinkler, H. (2002) A general approach to seismic performance assessment. Proc. International Conference on Advances and New Challenges in Earthquake Engineering Research, 19-20.‏
10.    Porter, K.A. (2003) An overview of PEER’s performance-based earthquake engineering methodology. Proc. International Conference on Applications of Statistics and Probability in Civil Engineering.‏
11.    Moehle, J. and Deierlein, G.G. (2004) A framework methodology for performance-based earthquake engineering. Proc. The 13th World Conference on Earthquake Engineering, pp. 3812-3814.‏
12.    Dall'Asta, A., Tubaldi, E. and Ragni, L. (2016) Influence of the nonlinear behavior of viscous dampers on the seismic demand hazard of building frames. Earthquake Engineering and Structural Dynamics, 45(1), 149-169.
13.    ‏Kitayama, S. and Constantinou, M.C. (2016) Probabilistic collapse resistance and residual drift assessment of buildings with fluidic self‐centering systems. Earthquake Engineering and Structural Dynamics, 45(12), 1935-1953.‏
14.    Landi, L., Lucchi, S., and Diotallevi, P.P. (2014) A procedure for the direct determination of the required supplemental damping for the seismic retrofit with viscous dampers. Engineering Structures, 71, 137-149.‏
15.    SAC Joint Venture (1994) Proc. The Invitational Workshop on Steel Seismic Issues. Report No. SAC 94-01, Los Angeles, CA.
16.    Krawinkler, H. (2000) State of the Art Report on Systems Performance of Steel Moment Frames Subject to Earthquake Ground Shaking. Prepared for the SAC Joint Venture, Published by the Federal Emergency Management Agency, FEMA-355 C, Washington, DC.‏
17.    American Society of Civil Engineers (2010) Minimum design loads for buildings and other structures. Amer Society of Civil Engineers (Vol 7).‏
18.    McKenna, F., Fenves, G.L. and Scott, M.H. (2015) Open System for Earthquake Engineering Simulation. Pacific Earthquake Engineering Research Center, Berkeley.
19.    Seo, C.Y., Karavasilis, T.L., Ricles, J.M. and Sause, R. (2014) Seismic performance and probabilistic collapse resistance assessment of steel moment resisting frames with fluid viscous dampers. Earthquake Engineering and Structural Dynamics, 43(14), 2135-2154.‏
20.    Ibarra, L.F. and Krawinkler, H. (2005) Global Collapse of Frame Structures under Seismic Excitations. Berkeley, CA: Pacific Earthquake Engineering Research Center.‏
21.    Haselton, C.B. and Deierlein, G.G. (2007) Assessing Seismic Collapse Safety of Modern Reinforced Concrete Moment Frame Buildings. Doctoral Dissertation, Stanford University.‏
22.    Lignos, D.G. and Krawinkler, H. (2010) Deterioration modeling of steel components in support of collapse prediction of steel moment frames under earthquake loading. Journal of Structural Engineering, 137(11), 1291-1302.‏
23.    Min, L.L.P.P. (2008) Norme Tecniche per le Costruzioni. Italian building code, adopted with D.M. 14/01/2008, published on S.O. n. 30 G.U.
24.    Ramirez, O.M., Constantinou, M.C., Kircher, C.A., Whittaker, A.S., Johnson, M.W., Gomez, J.D. and Chrysostomou, C.Z. (2001) Development and Evaluation of Simplified Procedures for Analysis and Design of Buildings with Passive Energy Dissipation Systems-Revision 01.‏
25.    Landi, L., Conti, F. and Diotallevi, P.P. (2015) Effectiveness of different distributions of viscous damping coefficients for the seismic retrofit of regular and irregular RC frames. Engineering Structures, 100, 79-93.‏
26.    Vamvatsikos, D. and Cornell, C.A. (2002) Incremental dynamic analysis. Earthquake Engineering and Structural Dynamics, 31(3), 491-514.‏
27.    Yakhchalian, M., Ghodrati Amiri, G. and Nicknam, A. (2014) A new proxy for ground motion selection in seismic collapse assessment of tall buildings. The Structural Design of Tall and Special Buildings, 23(17), 1275-1293.‏
28.    Yakhchalian, M., Ghodrati Amiri, G. and Eghbali, M. (2017) Reliable seismic collapse assessment of short-period structures using new proxies for ground motion record selection. Scientia Iranica, 25(5), 2283-2293.‏
29.    Yakhchalian, M., Nicknam, A. and Amiri, G.G. (2015) Optimal vector-valued intensity measure for seismic collapse assessment of structures. Earthquake Engineering and Engineering Vibration, 14(1), 37-54.
30.    Jamshidiha, H.R., Yakhchalian, M., and Mohebi, B. (2018) Advanced scalar intensity measures for collapse capacity prediction of steel moment resisting frames with fluid viscous dampers. Soil Dynamics and Earthquake Engineering, 109, 102-118.
31.    U.S. Geological Survey [Online] Available: http://geohazards.usgs.gov/hazardtool/application.php [2016, December 30].
32.    Eads, L. (2013) Seismic Collapse Risk Assessment of Buildings: Effects of Intensity Measure Selection and Computational Approach. Doctoral Dissertation, Stanford University.