نوع مقاله : مقاله پژوهشی
نویسندگان
1 دانشگاه تهران
2 دانشگاه تربیت مدرس
چکیده
روشهای عددی یکی از ابزارهای مورد استفاده برای تحلیل پاسخ لرزهای است، که در این میان روش اجزای مرزی جایگاه ویژهای دارد. در این پژوهش، مطالعه جامعی بر چگونگی تاثیر ابعاد المان و طول گام زمانی بر پایداری و دقت نتایج روش اجزای مرزی حوزه زمان صورت پذیرفته است. به این منظور دو پارامتر β و L/λ که بهطور گسترده در ادبیات فنی برای ارزیابی پایداری روشهای عددی شناخته شدهاند مورد استفاده قرار گرفتهاند. سه محیط همگن، شبههمگن و ناهمگن با تحلیل مجموعا 280 مدل عددی مورد مطالعه قرار گرفته و مشخص شده است که پایداری و دقت نتایج در تحلیل محیط ناهمگن وابستگی اساسی به دو پارامتر مذکور داشته و نتایج قابل قبول تنها هنگامی حاصل میشود که موج در هر گام زمانی فاصلهای در حدود یک چهارم تا نصف طول المان را طی کرده (β=0.24-0.40) و حداقل یک و نیم گره به ازای طول موج کمینه تعریف شود (λ/L >1.0). همچنین مشخص شد در تحلیل محیط ناهمگن، ضریب β مربوط به محیطی که سرعت کمتری دارد، تعیینکننده پایداری و دقت نتایج تحلیل اجزای مرزی حوزه زمان خواهد بود.
کلیدواژهها
عنوان مقاله [English]
Evaluation of the Stability of Time Domain Boundary Element Method in Seismic Analysis of Heterogeneous Environments
نویسندگان [English]
- Shahram Maghami 1
- Abdollah Sohrabi-Bidar 1
- Niloufar Babaadam 2
1
2
چکیده [English]
Numerical approaches are one of the best tools for seismic response analysis. In between, the Boundary Element Method (BEM) has attracted special attention. In this paper, a comprehensive study has been performed to characterize the dependence of stability and accuracy of the time domain BEM on the chosen time step duration and effective length of the elements. To this end, the two parameters β and λ/L, widely known and used in the literature for the investigation of numerical stability and accuracy, have been employed. Three different environments as homogeneous, pseudo-homogeneous and non- homogeneous have been analyzed through total number of 280 numerical models. It is found that the stability and accuracy of the used algorithm is considerably influenced by the mentioned parameters, in a way that stable and accurate results will be achieved merely when the wave travels one-fourth to less than half the element size during each time step (0.24<β<0.4) and also when at least one and a half node is defined per the shortest wave-length (λ/L>1.5). It also became clear that in the modeling of non-homogeneous environments, the β value for the environment with the lowest wave velocity specifies the range of acceptable results.
کلیدواژهها [English]
- Stability
- Numerical Intermittent Instability
- Boundary Elements
- Time Domain
- Time Step Duration
- Element Size
- β Parameter
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