ارزیابی موردی قابلیت اعتماد لرزه‌ای ساختمان‌های بتنی قالب‌تونلی با احتساب تأثیر پدیده‌ی اندرکنش خاک و سازه

نوع مقاله : Articles

نویسندگان

1 دانشکده مهندسی عمران، دانشگاه علم و فرهنگ

2 دانشکده مهندسی عمران، دانشگاه صنعتی خواجه‌نصیرالدین طوسی

چکیده

تجربیات حاصل از زلزله‌های گذشته، حاکی از تأثیر قابل­ملاحظه‌ی پدیده‌ی اندرکنش خاک و ‌سازهبر پاسخ‌های دینامیکی سازه‌های مرتفع، حجیم، وزین و سخت مستقر روی خاک‌های نسبتاً نرم است. کنترل تأثیر پدیده‌ی مذکور بر قابلیت اعتماد لرزه‌ایساختمان‌ها با سیستم نوین قالب‌تونلی، نظر به وزن زیاد و سختی قابل‌توجه سیستم، ضروری به نظر می‌رسد. در این مطالعه، خاک زیر ساختمان‌های قالب‌تونلی 5 و 10 طبقه به کمک فنرهایی به‌صورت خطی مدل شده و پس از تحلیل، ضمن کنترل پاسخ‌ها، با رویکردی احتمالاتی، سطح عملکرد ساختمان‌ها و ضرایب اطمینان در برابر لغزش و واژگونی حین زلزله در دو حالت بستر صلب و انعطاف‌پذیر‌ مورد ارزیابی و مقایسه قرار گرفته است. نتایج نشان می‌دهد، با افزایش ارتفاع ساختمان و شدت زلزله، پدیده‌ی اندرکنش خاک‌و‌سازه بر پاسخ‌های سازه شامل برش و جابه­جایی طبقات و نیز موقعیت شروع خرابی‌ها مؤثر بوده و نسبت به بستر صلب، می‌تواند احتمال رسیدن المان‌ها به اولین سطوح خرابی را تا 30 درصد و احتمال لغزش و واژگونی کلی ساختمان را حداقل 10 درصد افزایش دهد. به نظر می‌رسد که به­خصوص در مناطق با لرزه‌خیزی بالا و خاک‌های نرم، پدیده‌ی نامبرده می‌تواند سبب کاهش بازه‌ی قابلیت اعتماد سازه‌های بلند در حصول به عملکردهای از پیش تعیین شده گردد.

کلیدواژه‌ها


عنوان مقاله [English]

Seismic Reliability Assessment of Two Case-Study Tunnel Form Buildings Considering the Effect of Soil-Structure Interaction

نویسندگان [English]

  • Vahid Mohsenian 1
  • Saeed Asil Gharehbaghi 2
  • Seyed Bahram Beheshti-Aval 2
1 University of Science and Culture, Tehran, Iran
2 Civil Engineering Faculty, K.N. Toosi University of Technology, Iran
چکیده [English]

There are proven reasons indicating that during seismic excitation, considering substrate flexibility, i.e. Soil-Structure Interaction (SSI) may intensify displacement, change in internal members’ forces and damage and even lead to the collapse of the construction. Conventional structural design methods neglect the SSI effects. The lesson learnt from past earthquakes revealed a significant effect of SSI phenomena on the dynamic response of tall, bulky and heavy structures resting on relatively soft soils, for example, nuclear power plants, high-rise buildings, and elevated RC water tanks on soft soil. Neglecting SSI is reasonable for light weight structures in relatively stiff soil such as low-rise buildings.
The tunnel form buildings are one of these heavy and stiff systems that considering SSI may be important in modeling for seismic loading. To introduce, this system is a modern constructing technique that is recently used in mass construction projects This system lacks structural beams and columns in which only the elements of slab and wall as vertical and lateral load-bearing elements are used. The wall and upper slab are concreted at the same time. It seems that considering SSI phenomenon for such buildings concerning high lateral stiffness and weight, especially under strong earthquake or soft soil ground is of great importance. Despite widespread usage, unfortunately in the current design codes, the system is not considered as an independent structural system. Although there are valuable researches carried out on tunnel form buildings, they are still limited in a literature survey.
A literature survey shows that the experimental and numerical study to evaluate the seismic behavior of tunnel form buildings considering SSI effect is very limited. Now, in many densely populated cities with a relatively high risk of occurring earthquakes, this system is used as mass housing projects. Since the rigidity of soil bed below the foundation in analysis and design of these structures is a common assumption among designers, this study attempts to assess this presumption in a structural reliability framework. Therefore, in this study, these structures are examined through the considering SSI in analytical modeling and its influences on their seismic response and behavior. First 5 and 10-story regular buildings were designed with and without SSI modeling based on the current revision of Iranian seismic code. After controlling performance levels and responses based on probabilistic approach, the overturning and sliding factors were examined under seismic intensity levels of 0.35 and 0.65 corresponding to seismic hazard level of DBE (Design Base Earthquake) and MCE (Maximum Considered Earthquake).  
It is to be noted that in this study, the elastic behavior of soil was the basic premise assumption. The results show that, with increasing building height and intensity of earthquakes, the SSI phenomenon influenced the structural responses including shear and inter-story drifts and also commence of starting position of damages. The research results indicated that the first damage level probability could be increased up to 30% and the sliding and overturning
There are proven reasons indicating that during seismic excitation, considering substrate flexibility, i.e. Soil-Structure Interaction (SSI) may intensify displacement, change in internal members’ forces and damage and even lead to the collapse of the construction. Conventional structural design methods neglect the SSI effects. The lesson learnt from past earthquakes revealed a significant effect of SSI phenomena on the dynamic response of tall, bulky and heavy structures resting on relatively soft soils, for example, nuclear power plants, high-rise buildings, and elevated RC water tanks on soft soil. Neglecting SSI is reasonable for light weight structures in relatively stiff soil such as low-rise buildings.
The tunnel form buildings are one of these heavy and stiff systems that considering SSI may be important in modeling for seismic loading. To introduce, this system is a modern constructing technique that is recently used in mass construction projects This system lacks structural beams and columns in which only the elements of slab and wall as vertical and lateral load-bearing elements are used. The wall and upper slab are concreted at the same time. It seems that considering SSI phenomenon for such buildings concerning high lateral stiffness and weight, especially under strong earthquake or soft soil ground is of great importance. Despite widespread usage, unfortunately in the current design codes, the system is not considered as an independent structural system. Although there are valuable researches carried out on tunnel form buildings, they are still limited in a literature survey.
A literature survey shows that the experimental and numerical study to evaluate the seismic behavior of tunnel form buildings considering SSI effect is very limited. Now, in many densely populated cities with a relatively high risk of occurring earthquakes, this system is used as mass housing projects. Since the rigidity of soil bed below the foundation in analysis and design of these structures is a common assumption among designers, this study attempts to assess this presumption in a structural reliability framework. Therefore, in this study, these structures are examined through the considering SSI in analytical modeling and its influences on their seismic response and behavior. First 5 and 10-story regular buildings were designed with and without SSI modeling based on the current revision of Iranian seismic code. After controlling performance levels and responses based on probabilistic approach, the overturning and sliding factors were examined under seismic intensity levels of 0.35 and 0.65 corresponding to seismic hazard level of DBE (Design Base Earthquake) and MCE (Maximum Considered Earthquake).  
It is to be noted that in this study, the elastic behavior of soil was the basic premise assumption. The results show that, with increasing building height and intensity of earthquakes, the SSI phenomenon influenced the structural responses including shear and inter-story drifts and also commence of starting position of damages. The research results indicated that the first damage level probability could be increased up to 30% and the sliding and overturning
probability increased at least 10 percent considering SSI respect to non-SSI assumption. It may be concluded that, especially in areas with high seismicity and soft soils considering SSI can reduce the reliability of this type of structures to attain predetermined performance. Thus, in the case of areas with high seismicity, soft soil and for taller buildings, special attention to the phenomenon of SSI in the seismic assessment of this structural system is necessary.

کلیدواژه‌ها [English]

  • Tunnel Form System
  • Shear Wall
  • Soil-Structure Interaction
  • Structural Reliability
  • Seismic Fragility Analysis
  1. Getmiri, B., Tajoddini, H.R. (2003) The effects of nonlinear behavior of soil on dynamic responses of tall buildings. Journal of the College of Engineering, 37(2), 283-294 (in Persian).
  2. Hosseinzadeh, N., Nateghi-Alahi, F., and Behnamfar, F. (2004) Shake table study of soil-structure interaction effects on seismic response of adjacent buildings. Journal of Computational Methods in Engineering (Esteghlal), 22(2), 1-21 (in Persian).
  3. Hosseinzadeh, N., Davoodi, M., and Rayat Roknabadi, E. (2009) Comparison of soil-structure interaction effects between building code requirements and shake table study. Journal of Seismology and Earthquake Engineering, 11(1), 31-39.
  4. Hosseinzadeh, N., Davoodi, M., and Rayat Roknabadi, E. (2012) Shake table study of soil structure interaction effects in surface and embedded foundation. The 15th World Conference on Earthquake Engineering, 24-28 September, Lisbon, Portugal.
  5. Ghannad, M.A. and Ahmadnia A. (2006) The effect of soil-structure interaction on inelastic structural demands. European Earthquake Engineering, 20(1), 23-35.
  6. Ghannad, M.A. and Jahankhah H. (2007) Site dependent strength reduction factors for soil-structure systems. Soil Dynamics and Earthquake Engineering, 27(2), 99-110.
  7. Aviles, J. and Perez-Rocha, L.E. (2003) Soil-structure interaction in yielding systems. Earthquake Engineering and Structural Dynamics, 32(11), 1749-1771.
  8. Nakhaei, M. and Ghannad, M.A. (2008) The effect of soil-structure interaction on damage index of buildings. Earthquake Engineering, 30(6), 1491-1499.
  9. Goel, R.K. and Chopra, A.K. (1998) Period formulas for concrete shear wall buildings. Journal of Structural Engineering, 124(4), 426-433.
  10. Lee, L.H., Chang, K.K., and Chun, Y.S. (2000) Experimental formula for the fundamental period of RC building with shear wall dominant systems. The Structural Design of Tall Buildings, 9(4), 295-307.
  11. Balkaya, C. and Kalkan E. (2003) Estimation of fundamental periods of shear-wall dominant building structures. Earthquake Engineering & Structural Dynamics, 32(7), 985-998.
  12. Balkaya, C. and Kalkan, E. (2004) Relevance of R-factor and fundamental period for seismic design of tunnel-form building. 13th World Conference on Earthquake Engineering, Vancouver, Canada.
  13. Balkaya, C. and Kalkan, E. (2004) Seismic vulnerability, behavior and design of tunnel form building structures. Engineering Structures, 26(14), 2081-2099.
  14. Balkaya, C. and Kalkan, E. (2003) Seismic design parameters for shear-wall dominant building structures. The 14th National Congress on Earthquake Engineering, Guanajuato, Mexico.
  15. Yuksel, S.B. and Kalkan, E. (2007) Behavior of tunnel form buildings under quasi-static cyclic lateral loading. Structural Engineering and Mechanics, 27(1), 99-115.
  16. Kalkan, E. and Yuksel, S.B. (2007) Pros and cons of multistory RC tunnel-form (box-type) buildings. The Structural Design of Tall and Special Buildings, 17(3), 601-617.
  17. Tavafoghi, A. and Eshghi, S. (2008) Seismic behavior of tunnel form concrete building structures. The 14th World Conference on Earthquake Engineering, Beijing, China.
  18. Eshghi, S. and Tavafoghi, A. (2012) Experimental study of tunnel form buildings. Amir Kabir Journal of Science and Technology, 44(1), 31-42 (in Persian).
  19. Tavafoghi, A. and Eshghi, S. (2011) Evaluation of behavior factor of tunnel-form concrete building structures using applied technology council 63. The Structural Design of Tall and Special Buildings, 22(8), 615-634.
  20. Balkaya, C., Yuksel, S.B., and Derinoz, O. (2012) Soil-structure interaction effects on the fundamental periods of the shear-wall dominant buildings. The Structural Design of Tall and Special Buildings, 416-430, DOI: 10.1002/tal.611.
  21. Beheshti-Aval, S.B. and Mohsenian, V. (2017) Multi-level R-factor determination for RC tunnel-form buildings. Sharif Journal of Civil Engineering (Accepted, in Persian).
  22. Mohsenian, V., Beheshti-Aval, S.B., and Darbanian, R. (2017) Endurance time method, a suitable substitute for traditional dynamic analysis in seismic performance assessment of RC tunnel form buildings. Sharif Journal of Civil Engineering (Accepted, in Persian).
  23. Beheshti-Aval, S.B, Mohsenian, V., and Nikpour, N. (2015) Seismic characteristics of tunnel form concrete buildings with irregular plan. Journal of Solid and Fluid Mechanics, 5(3), 1-15.
  24. Beheshti-Aval, S.B., Mohsenian, V., and Nikpour, N. (2017) A study on seismic performance of RC tunnel form building structures with the irregular plan. Modares Civil Engineering Journal (Accepted, in Persian).
  25. Mohsenian, V., Rostamkalaee, S., Moghadam, A.S., and Beheshti-Aval, S.B. (2017) Evaluation of seismic sensitivity of tunnel form concrete buildings to mass eccentricity in plan. Sharif Journal of Civil Engineering (Accepted, in Persian).
  26. Mohsenian, V. (2013) R-Factor Determination for Tunnel-Form Buildings. M.Sc. Thesis University of Science and Culture, Iran, Tehran (in Persian).
  27. Permanent Committee for Revising the Standard 2800 (2014) Iranian Code of Practice for Seismic Resistant Design of Buildings, 4th Edition. Building and Housing Research Center, Tehran, Iran.
  28. ACI Committee 318 (2007) Building Code Requirements for Structural Concrete (ACI 318-08) and Commentary. American Concrete Institute.
  29. Computers and Structures Inc. (CSI) (2008) Structural and Earthquake Engineering Software, ETABS, Extended Three Dimensional Analysis of Building Systems Nonlinear. Version 9.5.0. Berkeley, CA, USA.
  30. Approved Technologies in Direction of Sub-Note 2-6, Paragraph "D", Note 6 (2007) A Step in Direction of Building Industrialization, First Edition. Building and Housing Research Center Press, Pages 21-22, (in Persian).
  31. Paulay, T. and Binney, J.R. (1974) Diagonally reinforced coupling beams of shear walls, shear in reinforced concrete. ACI Special Publications 42, 579-598.
  32. Computers and Structures Inc. (CSI) (2007) Structural and Earthquake Engineering Software, PERFORM-3D Nonlinear Analysis and Performance Assessment for 3-D Structures. Version 4.0.3, Berkeley, CA, USA.
  33. Computers and Structures Inc. (CSI) (2006) PERFORM-3D Nonlinear Analysis and Performance Assessment for 3-D Structures, User Guide. Version 4, August, Berkeley, CA, USA.
  34. Technical Criteria Codification & Earthquake Risk Reduction Affairs Bureau (2007) Instruction for Seismic Rehabilitation of Existing Buildings. No. 360, Management and Planning Organization, Iran.
  35. ASCE (2007) Seismic Rehabilitation of Existing Buildings. ASCE/SEI41-06, American Society of Civil Engineers.
  36. PEER Ground Motion Database, Pacific Earthquake Engineering Research Center, Web Site: http://peer.berkeley.edu/peer_ground_motion_ database
  37. Berahman, F. and Behnamfar, F. (2007) Seismic fragility curves for un-anchored on-grade steel storage tanks: Bayesian approach. Journal of Earthquake Engineering, 11(2), 166-192.
  38. Beheshti-Aval, S.B., Masoumi-Verki, A., and Rastegaran, M. (2014) Systematical approach to evaluate collapse probability of steel mrf buildings based on engineering demand and intensity measure. International Journal of Structural Analysis and Design – IJS, 1(2), 14-18.