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

مهندسی عمران فردوسی

مقاله 2، دوره 37، شماره 3 - شماره پیاپی 47، مهر 1403، صفحه 13-40   

نوع مقاله: مقاله پژوهشی

شناسه دیجیتال (DOI): 10.22067/jfcei.2024.85341.1271

نویسندگان

سید احمد نظامی^* ؛ جلیل شفائی

دانشکده مهندسی عمران، دانشگاه صنعتی شاهرود، شاهرود.

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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