بررسی شاخص قابلیت اعتماد تیر طراحی شده بر اساس آیین نامه طراحی ساختمانهای بتنی ایران (مبحث نهم)

نوع مقاله : مقاله پژوهشی

نویسنده

استادیار، دانشکده فنی و مهندسی، دانشگاه مازندران

چکیده

آیین نامه طراحی ایران با اعمال ضرایب اطمینان جزئی در بار و مقاومت، درصدد آن است تا سازه های طراحی شده را در محدوده ایمنی مشخصی قرار دهد. با محاسبه شاخص قابلیت اعتماد می توان به بررسی میزان ایمنی سازهها پرداخت. در این مقاله، شاخص قابلیت اعتماد تیر به عنوان عضو مهمی از سازه در نظر گرفته شده و چگونگی اثرگذاری مقادیر مختلف مؤلفه ها و ضرایب تغییرات آنها بر شاخص قابلیت اعتماد تیر بررسی می شود. در انتها نیز ضرایب اطمینان جزئی برای حالات مختلف ارائه می شود. به منظور محاسبه شاخص قابلیت اعتماد، از یک روش جدید بر مبنای الگوریتم ژنتیک استفاده می شود. این روش جدید در مقایسه با روش های سنتی و روش های شبیه سازی مانند مونت کارلو کارایی بیشتری دارد. زیرا از یک طرف به فرم ریاضی تابع حالت حدی نیازی نداشته و از طرفی دیگر، زمان محاسباتی نسبتاً کمی دارد.

کلیدواژه‌ها


عنوان مقاله [English]

Reliability-based Evaluation of Beams Designed in Accordance with Iranian Design Code

نویسنده [English]

  • E. Jahani
Assistant Professor, Faculty of Engineering and Technology, University of Mazandaran
چکیده [English]

Iranian design code like any other design code increases the reliability of a structure by means of
multiplying the partial safety factors by load and resistant. The reliability index can be evaluated in
order to survey the reliability of structures. In this paper, the reliability index of a beam as an important
member of a structure is considered and the effect of the values and coefficient of variation of design
parameters on the reliability index is surveyed. Finally, the partial safety factors for different states
are proposed. In this paper, a new method based on genetic algorithm (GA) is used to calculate the
reliability index. This new method has more efficiency in comparison with the classic methods and the
simulation methods such as Monte Carlo. This method does not require the mathematical form of the
limit state function and on the other hand, this method takes less computational time in comparison with
simulation methods. In structural construction, there are many different design parameters which are
random variables. Probability distribution can be considered for each of these random variables. For
different statistical data of design parameters, different partial safety factors are needed to optimum
design of a beam. However, Iranian design code considers the constant partial safety factors for all
different conditions. In case that the exact and specific statistical data of design parameters are available,
the structural reliability analysis can be applied for reaching an optimum design. The statistical data of
design parameters can be obtained by gathering the statistical data in any country and after that a reliable
design code can be obtained based on these statistical data. Because of lack of statistical data of design
parameters in Iran, five usual conditions were considered for data and then partial safety factors are
calculated.

کلیدواژه‌ها [English]

  • Reliability Theory
  • genetic algorithm
  • Reliability Index
  • Limit State Function
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