اثر اندرکنش خاک- سازه بر تقاضاهای لرزه ای سازه در روندهای طراحی و ارزیابی

نویسندگان

1 دانشگاه صنعتی بابل

2 دانشگاه صنعتی شریف

3 ندارد

چکیده

در این تحقیق، اثر شرایط خاک شامل هردو اثر ساختگاه و اندرکنش خاک – سازه روی تقاضاهای لرزه‌ای الاستیک و غیر الاستیک سازه مورد بررسی قرار گرفته است. تاکید بیشتر روی اثر اندرکنش خاک – سازه بوده و اثر ساختگاه با اعمال رکوردهای ثبت شده ‌بر خاک‌های سایت کلاس C، D و E (NEHRP[1]) که اثر اندرکنش در آن ها قابل ملاحظه می‌باشد، اعمال شده‌است. جهت انجام یک مطالعه آماری، سازه مورد بررسی، به صورت یک سیستم یک درجه آزادی با رفتار الاستوپلاستیک و خاک زیر سازه یک نیم فضای همگن در نظر گرفته شده‌است. به منظور درنظرگرفتن وابستگی فرکانسی سختی خاک، این نیم فصای همگن بر اساس مفهوم مدل مخروطی به صورت یک سیستم سه درجه آزادی مدل شده‌است. سپس کل سیستم خاک – سازه تحت 42 رکورد ثبت شده‌بر انواع سایت کلاس‌های عنوان شده ‌تحلیل گردیده‌است. یک مطالعه پارامتریک برای محدوده وسیعی از پارامترهای بی بعد تاثیرگذار بر اندرکنش خاک-سازه انجام گرفته است. نتایج تحقیق نشان می‌دهد که اثر اندرکنش خاک-سازه موجب تفاوت‌های محسوس و در مواردی غیرمحافظه کارانه در تقاضاهای لرزه‌ای سازه به خصوص در سایت کلاس‌های با خاک خیلی نرم می‌گردد. در نتیجه در نظر گرفتن اثر اندرکنش خاک-سازه در روند تحلیل یا طراحی سازه امری اجتناب ناپذیر به نظر می‌رسد.

کلیدواژه‌ها


عنوان مقاله [English]

Effect of soil-structure interaction on seismic demands of structures in evaluation and design procedures

نویسندگان [English]

  • Javad Vaseghi Amiri 1
  • Leila Khanmohammadi 1
  • Mohammad Ali Ghannad 2
  • mohammadreza davoodi 3
1
2
3 dont have
چکیده [English]

Effect of soil-structure interaction (SSI) and site condition on elastic and inelastic seismic demands of structure is investigated in this research. More emphasis is on Effect of soil-structure interaction and site condition is assessed by using earthquakes recorded on different site classes C, D and E (NEHRP [1]) where SSI has a significant effect on the structural demands because of noticeable difference between the stiffness of soil and the structure. In order to develop a comprehensive statistical parametric study, the structure is modeled as an elastic-plastic single degree of freedom (SDOF) system and the soil beneath the foundation is supposed as a homogeneous half space and is idealized by fundamental lumped mass parameters based on the concepts of the cone model (Wolf, 1994[17]). To consider the frequency dependency of soil’s dynamic stiffness in this model, the soil is represented with a three-DOF system that introducing an internal DOF in the soil can represent this effect. Then the whole of soil-structure model is analyzed under 45 earthquakes recorded on previously mentioned site classes. A parametric study is done for a wide range of non-dimensional parameters controlling the SSI effects on structural demands. It is concluded that SSI affects on structural seismic demands such as elastic and inelastic strength, strength reduction factor, ductility demand, and inelastic displacement ratio especially for structures located on site class E. Results exhibit remarkable differences in comparison to fixed base one. Consequently, in some cases, using parameters derived for fixed base case, lead to non-conservative results in design and assessment parameters of structures located on soft soils.

کلیدواژه‌ها [English]

  • soil-structure interaction
  • soil’s dynamic stiffness
  • frequency dependency of soil’s stiffness
  • elastic and inelastic strength
  • strength reduction factor
  • Ductility demand
  • and inelastic displacement ratio
1-      
[1] BSSC (2003). “NEHRP Recommended Provisions for Seismic Regulations for New Buildings and Other Structures”. FEMA 450, Washington.
[2] Veletsos, A.S., Meek, J.W. (1974). “Dynamic Behavior Building-Foundation Systems”. Earthquake Engineering and Structural Dynamic, Vol. 34, pp.121-138.
[3] Veletsos, A.S., Nair, V.V.D. (1975). “Seismic Interaction of Soil on Hysteretic foundation”. Journal of Structural Division, ASCE, Vol. 101, pp. 109-129.
[4] Wolf, J.P. (1985). “Dynamic Soil-structure Interaction”. Prentice Hall, New Jersey.
[5] Aviles, J., Perez-Rocha, L.E. (1999). “Diagrams of Effective Periods and Damping of Soil-structure Systems”. Journal of Geotechnical and Geo‌‌environmental Engineering, Vol. 125, pp. 711-715.
[6] Applied Technology Council (ATC), (1978). “Tentative Provisions for the Development of Seismic Regulations for Buildings”. ATC Publication, ATC3-06.
[7] IBC (2000). “International Building Code”. The International Conference of Building Officials (I.C.B.O.), USA.
[8] Bielak, J. (1978). “Dynamic Response of Non-linear Building-foundation Systems”. Earthquake Engineering and Structural Dynamic, Vol. 6, pp. 17-30.
[9] Aviles. J., Perez-Rocha, L.E. (2003). “Soil-structure Interaction in Yielding Systems”. Earthquake Engineering and Structural Dynamics, Vol. 32, pp. 1749-1771.
[10] Aviles, J., Perez-Rocha, L.E. (2005). “Design Concepts for Yielding Structures on Flexible Foundation”.  Engineering Structure, Vol. 27, pp. 443–454.
[11] Rodriguez, M. E., Montes, R., (2000). “Seismic Response and Damage Analysis of Buildings Supported on Flexible Soils”. Earthquake Engineering and Structural Dynamics, Vol. 29, pp. 647-665.
[12] Ghannad, M.A., Ahmadnia, A. (2006). “The Effect of Soil-structure Interaction on Inelastic Structural Demands”. Journal of  European Earthquake Engineering, Vol. 1, pp. 23–35.
[13] Barcena, A., Esteva, L. (2007) “Influence of Dynamic Soil Structure Interaction on the Nonlinear Response and Seismic Reliability of Multistory Systems”. Earthquake Engineering and Structural Dynamics, Vol, 36, pp. 327-346.
[14] Khoshnoudian, F., Behmanesh, I. (2010). “Evaluation of FEMA-440 for including soil-structure interaction”. Earthquake Engineering and Engineering Vibration, Vol. 9, pp. 397-408.
[15] EMA-440 (2005), “Improvement of Nonlinear Static Seismic Procedures”. ATC-55 Draft, Washington.
[16] Ghannad, M.A., Fukuwa, N., Nishizaka, R. (1998). “A Study on the Frequency and Damping of Soil-structure System Using a Simplified Model”. Journal of Structural Engineering, Architectural Institute of JAPAN, AIJ, Vol. 44B, pp. 85-93.
[17] Wolf, J.P. (1994). “Foundation Vibration Analysis Using Simple Physical Models”. Prentice-Hall, Englewood Cliffs, NJ.
[18] Ghannad, M.A., Jahnkhah, H., (2006). “Discussion of Influence of Foundation Flexibility on and  Factors by Javier Aviles and Luis Eduardo Perez-Rocha”. Journal of Structural Engineering, JUNE, pp. 99-110.
[19] Meli, R., and Avila, J. (1988). “Analysis of building response.” Earthquake Spectra, Vol. 5(1), pp. 1–18.
[20] Miranda, E. (1993). “Site-dependent strength reduction factors”. Journal of Structural Engineering, Vol. 119(12), pp. 3503–3519.
[21] FEMA-356 (2000). “Pre‌‌standard and Commentary for the Seismic Rehabilitation of Buildings”, Federal Emergency Management Agency.
[22] Ruiz-Garcia, J., Miranda, E. (2003). “Inelastic Displacement Ratios for Evaluation of Existing Structures”. Earthquake Engineering and Structural Dynamics, Vol. 32, pp. 1237-1258.
[23] Chopra, A.K., Chintanapakdee, C. (2006). “Inelastic Deformation Ratios for Design and Evaluation of Structures: Single-Degree-of-Freedom Bilinear Systems”. Journal of Structural Engineering, Vol. 130 (9), pp. 1309-1319.
[24] Ruiz-Garcia, J., Miranda, E. (2006). “Inelastic Displacement Ratios for Evaluation of Structures Built on Soft Soil Sites”. Earthquake Engineering and Structural Dynamics, Vol. 35, pp. 679-694.
[25] Veletsos, A.S., Newmark, N.M. (1960). “Effect of Inelastic Behavior on the Response of Simple Systems to Earthquake Motions”. 2nd World Conference on Earthquake Engineering, Vol. 2, Tokyo, pp. 895-912.
[26] Kreslin, M., Fajfar, P. (2011). “The extended N2 Method Taking in to Account Higher Mode Effects in Elevation”. Earthquake Engineering and Structural Dynamics, Vol. 40, pp. 1571-1589.
[27] Bielak, J. (1976). “Modal Analysis for Building Soil Interaction", Journal of the Engineering Mechanics, Vol. 102, pp. 771-786.
[28] Tasi, N. (1974). “Modal Damping for Soil Structure Interaction", Journal of the Engineering Mechanics, Vol. 100, pp. 323-341.
[29] Tang, Y., Jian Zhang, J. (2011). “Probabilistic seismic demand analysis of a slender RC shear wall considering soil-structure interaction effects”, Journal of Engineering Structures, Vol. 33, pp. 218-229.
[30] Tileylioglu, S., Stewart, J. P., Nigbor, R. L. (2011). “Dynamic Stiffness and Damping of a Shallow Foundation from Forced Vibration of a Field Test Structure”, Journal Of Geotechnical And Geoenvironmental Engineering, Vol. 137, No. 4, pp. 344-353.
[31] Clouteau, D., Broc, D., Deve´sa, G., Guyonvarh, V., Massin, P. (2012). “Calculation methods of Structure-Soil-Structure Interaction‌(3SI) for embedded buildings: Application to NUPEC tests”, Journal of Soil Dynamics and Earthquake Engineering, Vol. 32, pp. 129-142.