مقایسه طیف شبه شتاب بدست آمده از درونیابی خطی تحریک با طیف شبه شتاب حاصل از درونیابی با تابع اسپلاین مکعبی

نوع مقاله : علمی - پژوهشی

نویسندگان

1 استادیار، دانشکده فنی و مهندسی، دانشگاه قم، قم، ایران

2 دانشجوی دکتری عمران سازه، دانشکده فنی و مهندسی، دانشگاه قم، قم، ایران.

3 دانشجوی دکتری عمران سازه، دانشکده عمران، دانشگاه صنعتی نوشیروانی بابل، بابل، ایران.

4 دانشجوی کارشناسی ارشد عمران سازه، دانشکده فنی و مهندسی، دانشگاه قم، قم، ایران.

چکیده

در این مقاله، طیف‌های شبه شتاب سه شتابنگاشت السنترو، ناغان و طبس که با روش درونیابی خطی تحریک (روش جنینگز) و نیز با استفاده از تابع اسپلاین مکعبی بدست آمده بودند، با یکدیگر مقایسه شده‌اند. روش جنینگز مبتنی بر درونیابی خطی تحریک می‌باشد و برای بازه های زمانی کوتاه قابل قبول است. در این پژوهش، سه شتابنگاشت ال‌سنترو، ناغان و طبس در نظر گرفته شدند و طیف پاسخ شبه شتاب همپایه شده (ضریب برش پایه) آنها برای مقادیر میرایی‌های مختلف با استفاده از روش درونیابی خطی و نیز درونیابی با تابع اسپلاین محاسبه گردیدند. میرایی های در نظر گرفته شده برابر با مقادیر صفر، دو، پنج، ده و بیست درصد بود. برای اینکه تفاوت روش درونیابی خطی و روش درونیابی با تابع اسپلاین مشخص شود، فاصله زمانی بین نقاط شتابنگاشت به ترتیب به 100،50،20،10،5،2 و200 قسمت مساوی تقسیم گردید. سپس، یکبار با روش درونیابی خطی و بار دیگر با روش درونیابی اسپلاین نقاط داخلی بین نقاط شتابنگاشتها بدست آورده شد و طیف شبه شتاب آنها با استفاده از روش جنینگز و روش درونیابی با تابع اسپلاین محاسبه گردید. نتایج محاسبات نشان داد که مقادیر طیف شبه شتاب محاسبه شده با روش درونیابی اسپلاین در دوره تناوبهای خیلی کوچک و میرایی‌های کم، اختلاف قابل ملاحظه‌ای با مقادیر متناظر طیف شبه شتاب محاسبه شده با روش درونیابی خطی دارد. لازم به ذکر است فاصله زمانی اولیه بین نقاط شتابنگاشتهای السنترو، ناغان و طبس 02/0 ثانیه می‌باشد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Comparison of pseudo-acceleration spectrum obtained from linear interpolation of excitation with pseudo-acceleration spectrum obtained from interpolation with cubic spline function

نویسندگان [English]

  • Masooud Mahmoudabadi 1
  • Babak Taqavi 2
  • Seyed mohammad Reza Hasani 3
  • seyed mohammad javad Hosseini 4
1 Assistant Professor, Department of Civil Engineering, Faculty of Technology and the University of Qom, Qom, Iran
2 Phd student, Department of engineering, University of Qom, Qom, Iran
3 Phd student, Faculty of Civil Engineering, Babol Noshirvani University of Technology, Babol. Iran
4 Master's student in Technical and Engineering Faculty, Qom University, Qom, Iran.
چکیده [English]

In this paper, the pseudo-acceleration spectra of the three accelerograms of El Centro, Naghan and Tabas, which were obtained by the linear interpolation method of stimulation (Jennings’s method) and also by using the cubic spline function, are compared with each other. Jennings' method is based on linear interpolation of excitation and is acceptable for short periods of time. In this research, three accelerograms of El Centro, Naghan and Tabas were considered, and their pseudo-acceleration response spectrum (base shear coefficient) was calculated for different damping values using linear interpolation method and interpolation with spline function. The considered damping were zero, two, five, ten and twenty percent. In order to determine the difference between the linear interpolation method and the spline function interpolation method, the time interval between the accelerometer points was divided into 2, 5, 10, 20, 50, 100, and 200 equal parts, respectively. Then, once with the linear interpolation method and again with the spline interpolation method, the internal points between the internal acceleration points were obtained and their pseudo-acceleration spectrum was calculated using the Jennings method and the interpolation method with the spline function. The calculation results showed that the pseudo-acceleration spectrum values calculated by the spline interpolation method in very short periods and low damping have a significant difference with the corresponding values of the pseudo-acceleration spectrum calculated by the linear interpolation method. It should be noted that the initial time interval between the accelerogram points of El Centro, Naghan and Tabas is 0.02 seconds.

کلیدواژه‌ها [English]

  • Linearly interpolated excitation
  • Cubic spline function
  • Single-degree-of-freedom system
  • Normalized pseudo-acceleration
  • Base shear coefficient
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