مصالح و سازه های بتنی

مصالح و سازه های بتنی

تأثیر مقاومت مشخصه بتن در قابلیت اعتماد پدیده تیر ضعیف – ستون قوی

نوع مقاله : مقاله پژوهشی

نویسندگان
محمد جواد فدائی فتح آبادی 1
حمیدرضا عزیززاده فروزی 2
1 استاد دانشکده فنی و مهندسی، بخش مهندسی عمران ، دانشگاه شهید باهنر کرمان
2 دانشجوی دکتری، دانشکده فنی و مهندسی، بخش مهندسی عمران ، دانشگاه شهید باهنر کرمان
10.30478/jcsm.2026.540669.1401
چکیده
بررسی قابلیت اعتماد معیار تیر ضعیف - ستون قوی در سازه‌ها، از موضوعات کلیدی در طراحی ساختمان‌های مقاوم در برابر زلزله به شمار می‌رود. شرط اصلی تحقق این معیار، که در مباحث نهم و دهم مقررات ملی ساختمان ایران نیز بر آن تأکید شده، برتری ظرفیت خمشی ستون‌ها بر ظرفیت خمشی تیرها در هر گره سازه‌ای است. این پژوهش به ارزیابی احتمال وقوع شکست تیرها پیش از ستون‌ها می‌پردازد و در این مسیر، بر یکی از پارامترهای احتمالی مؤثر، یعنی مقاومت فشاری بتن، تمرکز دارد. تصادفی بودن مقاومت فشاری مشخصه بتن به این معنی است که این مقاومت یک عدد قطعی نیست بلکه میانگین مقاومت چند نمونه با مقداری انحراف معیار میباشد. سایر پارامترها مانند مقاومت مصالح فولاد و ابعاد مقاطع به صورت قطعی در نظر گرفته شده‌اند.

در این مطالعه، با به‌کارگیری مدل‌سازی احتمالی و تعریف تابعی برای توزیع احتمالی مقاومت فشاری بتن، تأثیر تغییرات این مقاومت بر احتمال برقراری شرط تیر ضعیف - ستون قوی بررسی شده است. این تابع با استفاده از معادلات حاکم بر تعادل لنگرها استخراج شده است. نتایج به‌وضوح نشان می‌دهند که تغییر مقادیر میانگین و انحراف معیار در توزیع نرمال مقاومت بتن، احتمال تحقق این شرط را به‌طور معناداری تغییر می‌دهد. این یافته‌ها، اهمیت توجه به عدم قطعیت‌های ذاتی در مشخصات مصالح و لزوم استفاده از روش‌های مبتنی بر قابلیت اعتماد در فرآیند طراحی سازه‌ها را پررنگ می‌نماید.
کلیدواژه‌ها
قابلیت اعتماد سازه
تیر ضعیف - ستون قوی
مقاومت فشاری بتن
توزیع احتمال نرمال
عدم قطعیت
موضوعات

عنوان مقاله English

The Effect of Concrete Characteristic Strength on the Reliability of the Weak Beam – Strong Column Phenomenon

نویسندگان English

Mohammad Javad Fadaee Fathabadi 1
Hamidreza Azizzadeh Forouzi 2
1 Professor, Civil Engineering Department, Faculty of Engineering, Shahid Bahonar University of Kerman
2 Ph. D. Candidate, Civil Engineering Department, Faculty of Engineering, Shahid Bahonar University of Kerman,
چکیده English

The reliability analysis of the "Weak Beam-Strong Column" phenomenon is recognized as a critical subject in the design of earthquake-resistant structures. Investigation on the "Weak Beam-Strong Column" phenomenon indicates that this principle depends on multiple parameters including geometric properties of the members and their physical characteristics. For reinforced concrete frames, the parameters include geometric properties such as beam and column dimensions, reinforcement area, and reinforcement placement in the sections (concerning effective depth), as well as physical properties including elastic modulus of the materials and material strengths.

The specific subject of this paper is the reliability analysis of the "Weak Beam-Strong Column" condition. In structural design, reliability refers to the probability of a structure maintaining its expected performance under stochastic conditions. For the "Weak Beam-Strong Column" phenomenon, this reliability can serve as an indicator of structural behavior under dynamic effects such as earthquakes or other loadings.

In this study, through probabilistic modeling and by defining a probability function for concrete compressive strength – derived from the governing moment equilibrium equations – the probability of fulfilling this condition under variations in concrete compressive strength has been investigated.

The results emphasize that material uncertainties in construction cannot be ignored in component design. This principle is recognized as fundamental in modern codes such as FEMA guidelines. However, a key limitation of this research is its exclusive focus on concrete compressive strength without consideration of other stochastic parameters such as steel tensile strength variability, cross-sectional geometric variations, or material fatigue effects.

These findings could facilitate the development of reliability-based design guidelines that incorporate inherent material uncertainties in calculations. The outcome may optimize both structural safety and economic efficiency.

کلیدواژه‌ها English

Structural reliability
Weak beam - strong column
Concrete compressive strength
Normal probability distribution
Uncertainty
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  • تاریخ دریافت 08 مهر 1404
  • تاریخ بازنگری 29 آبان 1404
  • تاریخ پذیرش 16 اردیبهشت 1405