توسعه الگوریتم تولید رکوردهای تکیه‌گاهی غیریکنواخت با استفاده از روش المان مرزی سه‌بعدی در حوزه زمان

نوع مقاله : مقاله کامل پژوهشی

نویسندگان

1 دانشکده مهندسی عمران، دانشگاه تبریز

2 دانشکده زمین شناسی، دانشگاه تهران

چکیده

برای پیش­بینی و تولید شتاب در نقاط مختلف تکیه­گاه سد، براساس رکوردهای ثبت شده یک یا چند شتاب سنج در ساختگاه سد، تلاش­های زیادی انجام گرفته است. در این پژوهش سعی شده است، با استفاده از روش المان مرزی سه­بعدی در حوزه زمان، مدل­سازی سه­بعدی که از ساختگاه سد پاکویما انجام گرفته، تحت تحریک غیر یکنواخت تکیه­گاهی بررسی شود. ساختگاه مدل شده، تحت امواج مهاجم قائم SV در فرکانس­های غالب و سرعت­های موج برشی مختلف، بررسی شد. برای نقاط در ارتفاعات مختلف در دو سمت دره، با استفاده از تابع خطی دیگر همبستگی، تأخیر زمانی نسبت به کف دره محاسبه شد. در نهایت با استفاده از نرم­افزارهای آماری قدرتمند موجود، روابط آماری برای تأخیر زمانی در دو سوی دره بر مبنای ارتفاع نقاط، سرعت موج برشی و فرکانس غالب ارئه شده است. با جایگزینی توابع تأخیر زمانی به دست آمده در الگوریتم مورد بررسی، رکوردهای تکیه­گاهی در نقاط مختلف تولید و با رکوردهای ثبت شده مقایسه شد. نتایج به دست آمده نشان­دهنده دقت بالای توابع تأخیر زمانی ارائه شده می­باشد. بنابراین می­توان از روش توسعه داده شده در این پژوهش برای تولید رکوردهای تکیه گاهی از روی یک رکورد در کف دره در صورت داشتن یک تابع بزرگ­نمایی متناسب با ساختگاه، به جای روش میانه­یابی که در آن حداقل به سه رکورد واقعی نیاز هست، استفاده کرد.

کلیدواژه‌ها


عنوان مقاله [English]

Extension of Algorithm for Support Non-Uniform Record Using Time Domain 3D Boundary Elements Method

نویسندگان [English]

  • Mohsen Isari 1
  • Reza Tarinejad 1
  • Abdullah Sohrabi-Bidar 2
1 Faculty of Civil Engineering, University of Tabriz, Tabriz
2 School of Geology, University of Tehran
چکیده [English]

It is well established that the seismic ground response of surface topographies may differ from those of free field motion during earthquakes. Although the topography effect on ground response can be crucial when the wavelength is comparable to irregularity dimensions, only a few building codes have considered this issue. This is because of the complex nature of seismic wave scattering by topographical structures, which can only be solved accurately and economically using advanced numerical methods under realistic conditions. Among the numerical methods, the BEM is a very effective tool for dynamic analysis of linear elastic bounded and unbounded media. In this research, a three-dimensional model of the Pacoima dam site is prepared. Time domain 3D boundary element method is used to apply the non-uniform excitation at the dam supports. This model is subjected to the vertically propagating incident S waves. Time delay can be characterized by calculating the value of time delay for which the cross-correlation between two records is maximized. Finally, to obtain the time delay in topographic site, a function considering effective parameters such as the height from the canyon base, wave velocity and predominant frequency, is presented. Furthermore, a code was developed for generating the spatial variation of seismic ground motions.

کلیدواژه‌ها [English]

  • time delay
  • Boundary Element
  • Wave Scattering
  • Non-Uniform Record
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