مدل‌سازی غیرخطی دستک فشاری و کششی برای اتصالات بهسازی‌شده به روش بزرگ‌کردن ناحیه اتصال و پیش‌تنیدگی

نوع مقاله : مقاله پژوهشی

نویسندگان

• سید احمد نظامی
• جلیل شفائی

دانشکده مهندسی عمران، دانشگاه صنعتی شاهرود، شاهرود.

10.22067/jfcei.2024.85341.1271

چکیده

ضرورت تقویت اتصالات تیر به ستون که بدون رعایت جزئیات لرزه‌ای ساخته شده‌اند، به طور قطع موضوعی زنده و پر اهمیت می‌باشد. آسیب در اتصال به عنوان یکی از نگران‌کننده‌ترین علل فروپاشی زنجیره‌ای ساختمان در زلزله‌های موثر گزارش می‌شود. عدم حضور خاموت ستون در ناحیه اتصال و عدم تامین گیرداری کافی آرماتور مثبت تیر در ناحیه اتصال کماکان ضعف‌های لرزه‌ای موجودی هستند که همچنان زمینه بررسی و ارائه طرح بهسازی متناسب با آن پر رنگ می‌باشد. روش دستک فشاری و کششی بر پایه دانش مبتنی بر روش اجزامحدود، ابزار توانمند و قابل توسعه در حوزه غیرخطی می‌باشد. در این پژوهش بر اساس روش دستک‌فشاری و کششی مدل‌های تحلیلی برای ارزیابی اتصالات تیر-ستون کناری بتن‌آرمه با جزئیات لرزه‌ای، غیرلرزه‌ای و تقویت‌شده با روش بزرگ‌کردن ناحیه اتصال ارائه می‌شود. نتایج حاصل از مدلسازی غیرخطی دستک فشاری و کششی نمونه‌های تقویت‌شده و تقویت‌نشده نشان می‌دهد که این مدل از توانایی تشخیص اثر تسلیح برشی ناحیه اتصال در ظرفیت برشی و مکانیزم‌های غیرخطی فعال‌شده از جمله لغزش جزئی و کلی آرماتورهای طولی تیر در اتصال برخوردار می‌باشند. همچنین میزان تاثیرگذاری ابعاد بزرگ‌شدگی اتصال در طرح بهسازی و زوال سختی و مقاومت از دیگر قابلیتهای مدل خرپاگونه معادل پیشنهاد شده می‌باشد. استفاده از مدل دستک فشاری و کششی در اتصالات موجود و تقویت‌شده منجر به تخمین ظرفیت نیروی حداکثر نمونه با دقت%6 بر اساس نتایج آزمایشگاهی همراه بوده‌است. در پیش‌بینی سختی موثر نمونه‌ها، مدل‌های دستک فشاری و کششی توانست %25 پاسخ همگراتری نسبت به نتایج بدست‌آمده از مدل‌ اجزامحدود بر مبنای نتایج آزمایشگاهی ارائه کند.

کلیدواژه‌ها

• اتصالات تیر به ستون
• ساختمان‌های بتن‌مسلح
• روش دستک فشاری و کششی
• بزرگ‌کردن ناحیه اتصال
• خرپای غیرخطی معادل

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عنوان مقاله [English]

Non-Linear Strut and Tie Modelling Approach of Retrofitted Reinforced Concrete Beam Column Joint by Prestress Joint Enlargement

نویسندگان [English]

• S.Ahmad Nezami
• Jalil Shafaei

Faculty of Civil Engineering, Shahrood University of Technology, Shahrood, Iran

چکیده [English]

The need to retrofitted beam-to-column joints, which are made without observing seismic details, is definitely a live and important issue. Connection damage is reported as one of the most worrying causes of building chain collapse in effective earthquakes. The absence of transverse reinforcement and insufficient bond length of the beam bottom bars in the joint area are still existing seismic weaknesses, which are still the subject of investigation and presentation of a corresponding improvement plan. The strut and tie method based on the knowledge based on the finite element method is a powerful and developable tool in the nonlinear field. In this research, analytical models are presented for the evaluation of reinforced concrete side beam-column joints with seismic, non-seismic and strengthened details based on the method of joint enlargement based on the strut and tie methods. The results of the nonlinear modeling of the strut and tie of retrofitted and un-retrofitted specimen show that this model has the ability to detect the effect of shear reinforcement of the joint area on the shear capacity and activated nonlinear mechanisms, including partial and total slip of the longitudinal beam reinforcements in the joint. Also, the influence of the dimensions of the enlargement of the joint in the design of rehabilitation and deterioration of stiffness and resistance is one of the other capabilities of the proposed equivalent truss-type model.

کلیدواژه‌ها [English]

• Beam-Column Joints
• Reinforced Concrete Structures
• Strut and Tie Method
• Joint Enlargement
• Equivalent Non-Linear Truss

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