IJE TRANSACTIONS A: Basics Vol. 31, No. 7 (July 2018) 1346-1354    Article in Press

downloaded Downloaded: 0   viewed Viewed: 79

N. Farhadi, H. Saffari and P. Torkzadeh
( Received: December 25, 2017 – Accepted: February 18, 2018 )

Abstract    In structural analysis the base of structures is usually assumed to be rigid. It is well-known that structural responses can be significantly affected by incorporating Soil-Structure Interaction (SSI) effects. The aim of the present study is to provide more accurate structural responses analysis by considering the influence of SSI. The input ground motions are selected in a such way that their characteristics are completely matched with the subsurface soil of structures. For this purpose, 3, 6, 9, 12, 15, 18 and 20-storey structures are selected and the concept of Beam on Nonlinear Winkler Foundation (BNWF) model is employed. Seismic responses of these structures are calculated based on the five different types of soil and are compared with those from fixed-base structures. A group of 35 ground motion excitations recorded on different soil types, are selected which categorized to 5 sets consist of 7 records. Non-Linear Response History Analysis (NL-RHA) is performed and for all of the structures and soil types investigated, the radiation damping is considered. The results show that the inter-storey drift ratio is reduced in lower stories considering SSI. These effects are strongly increased, especially with increasing the slenderness ratio of the structures and softening the subsurface soil.


Keywords    SSI, inter-story drift, BNWF, radiation damping, NL-RHA


چکیده    در تحلیل سازه­ها معمولا تکیه­گاه سازه گیردار در نظر گرفته می­شود. کاملا آشکار است که پاسخ­های سازه­ای متاثر از اندرکنش بین خاک و سازه می­باشند. هدف از مطالعه حاضر، بررسی دقیق­تر پاسخ سازه­ها با در نظر گرفتن اثر اندرکنش خاک و سازه می­باشد. شتاب­نگاشت­ها به نحوی انتخاب گردیده­اند که مشخصات آن­ها کاملا منطبق با خاک زیر سازه می­باشد. برای این منظور ساختمان­هایی با تعداد طبقات 3، 6، 9، 12، 15، 18 و 20 در نظر گرفته شده­اند. همچنین از مدل تیر بر فونداسیون غیر خطی وینکلر استفاده گردیده است. پاسخ­های لرزه­ای این سازه­ها بر روی پنج دسته خاک مختلف محاسبه و با پاسخ­های سازه­ای با پایه گیردار مقایسه شده­اند. یک مجموعه شامل 35 شتاب­نگاشت که بر روی خاک­های مختلف ثبت شده­اند، در قالب 5 دسته 7 تایی طبقه­بندی گردیده­اند. این سازه­ها تحت تحلیل تاریخچه زمانی دینامیکی غیر خطی با در نظر گرفتن میرایی شعاعی، مورد بررسی قرار می­گیرند. نتایج نشان می­دهد که نسبت دریفت بین طبقه­ای در طبقات پایین با در نظر گرفتن اثرات اندرکنش خاک و سازه، کاهش می­یابد. با افزایش نسبت لاغری سازه­ها و همچنین نرم­تر شدن خاک زیرین آن­ها، این اثرات چشم­گیرتر می­شوند.

References    1. NIST GCR 12-917-21, “Soil-Structure Interaction for Building Structures”, (2012). 2. Wolf, J.P., “Dynamic Soil-Structure Interaction”, Englewood Cliffs, Prentice-Hall, (1985). 3. Gazetas, G., “Formulas and charts for impedances of surface and embedded foundation”, Journal of Geotechnical Engineering, Vol. 117, No. 9, (1991), 1-15. 4. Wolf, J.P., “Spring-dashpot-mass models for foundation vibrations”, Earthquake Engineering and Structural Dynamics, Vol. 26, No. 9, (1997), 931-949. 5. Raychowdhury, P., and Hutchinson, T.C., “Performance evaluation of a nonlinear winkler-based shallow foundation model using centrifuge test results”, Earthquake Engineering and Structural Dynamics, Vol. 38, No. 5, (2009), 679-698. 6. Gajan, S., Raychowdhury, P., Hutchinson, T.C., Kutter, B.L. and Stewart, J.P. “Application and validation of practical tools for nonlinear soil-foundation interaction analysis”, Earthquake Spectra, Vol. 26, No. 1, (2009), 111-129. 7. Raychowdhury, P., “Seismic response of low-rise steel moment-resisting frame (SMRF) buildings incorporating nonlinear soil-structure interaction (SSI)”, Engineering Structures, Vol. 33, No. 3, (2011), 958-967. 8. Raychowdhury, P. and Raychaudhuri, S., “Seismic response of nonstructural components supported by a 4-storey SMRF: effect of nonlinear soil-structure interaction”, Structures, Vol. 3, No. 8, (2015), 200-210. 9. Paolucci, R., Figini, R., and Petrini, L., “Introducing dynamic nonlinear soil-foundation-structure interaction effects in displacement-based seismic design”, Earthquake Spectra, Vol. 29, No. 2, (2013), 475-496. 10. Bhaumik, L. and Raychowdhury, P., “Seismic response analysis of a nuclear reactor structure considering nonlinear soil-structure interaction”, Nuclear Engineering and Design, Vol. 265, No. 12, (2013), 1078-1090. 11. Tabatabaiefar, H.R. and Fatahi, B., “Idealisation of soil-structure system to determine inelastic seismic response of mid-rise building frames”, Soil Dynamics and Earthquake Engineering, Vol. 66, No. 11, (2013a), 339-351. 12. Tabatabaiefar, S.H.R., Fatahi, B. and Samali, B., “Seismic behavior of building frames considering dynamic soil-structure interaction”, International Journal of Geomechanics, Vol. 13, No. 4, (2013b), 409-420. 13. Gheyratmand, C. “Employing foundation nonlinearity to mitigate seismic demand in superstructure”, International Journal of Engineering, Transactions B: Applications, Vol. 29, No. 5, (2016), 606-614. 14. Behnamfar, F. and Banizadeh. M. “Effects of soil-structure interaction on distribution of seismic vulnerability in RC structures”, Soil Dynamics and Earthquake Engineering, Vol. 80, No. 1, (2016), 73-86. 15. Kalatjari, V.R., Naghizadeh, A., Naderi, R. and Talebpour, M.H. “Base level evaluation in buildings with different foundation levels by soil-foundation-structure interaction”, International Journal of Engineering, Transactions C: Aspects, Vol. 30, No. 9, (2017), 1288-1297. 16. Behnamfar, F. and Fathollahi, A. “Soft soil seismic design spectra including soil-structure interaction”, International Journal of Engineering, Transactions A: Basics, Vol. 30, No. 10, (2017), 1443-1450. 17. Sarlak, A., Saeedmonir, H. and Gheyretmand, C. “Numerical and Experimental study of soil-structure interaction in structures resting on loose soil using laminar shear box”, International Journal of Engineering, Transactions B: Applications, Vol. 30, No. 11, (2017), 1654-1663. 18. Ghandil, M. and Behnamfar, F. “Ductility demands of MRF structures on soft soils considering soil-structure interaction”, Soil Dynamics and Earthquake Engineering, Vol. 92, No. 1, (2017), 203-214.   19. Boulanger, R.W., Curras, C.J., Kutter, B.L., Wilson, D.W. and Abghari, A., “Seismic soil-pile-structure interaction experiments and analyses”, Journal of Geotechnical and Geoenvironmental Engineering, Vol. 125, No. 9, (1999), 750-759. 20. OpenSEES, Open System for Earthquake Engineering Simulation, Berkeley, California, USA, http://opensees.berkeley.edu/, (2017). 21. FEMA P-1050-1, “Recommended Seismic Provisions for New Buildings and other Structures”, (2015). 22. NIST GCR 11-917-15, “Selecting and Scaling Earthquake Ground Motions for Performing Response-History Analyses”, (2011). 23. PEER, The Pacific Earthquake Engineering Research Center, University of California, Berkeley, USA, http://peer.berkeley.edu/, (2017). 24. ASCE/SEI 41-13, “Seismic Evaluation and Retrofit of Existing Buildings”, 2014. 25. ASCE/SEI 7-10, “Minimum Design Loads for Buildings and other Structures”, 2013. 26. USGS, United States Geological Survey, Reston, Virginia, USA, https://www.usgs.gov/, (2017). 27. Karavasilis, T.L., Bazeos, N., and Beskos, D.E., “Maximum displacement profiles for the performance based seismic design of plane steel moment resisting frames”, Engineering Structures, Vol. 28, No. 1, (2006), 9-22. 28. CTBUH. Council on Tall Buildings and Urban Habitat Chicago, Illinois, USA, http://www.ctbuh.org/, (2017).

International Journal of Engineering
E-mail: office@ije.ir
Web Site: http://www.ije.ir