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
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-      

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