تأثیر پیش‌تنیدگی در پاسخ دینامیکی دال های بتنی در برابر انفجار

امامزاده, سید شهاب

تأثیر پیش‌تنیدگی در پاسخ دینامیکی دال های بتنی در برابر انفجار

نوع مقاله : مقاله پژوهشی

نویسنده

سید شهاب امامزاده

عضو هیات علمی گروه عمران، دانشگاه خوارزمی

چکیده

این پژوهش به‏منظور بررسی توانایی دال‏های پیش‏تنیده بتنی در مقابل انفجار با اهداف پدافند غیرعامل به روش سازهای صورت پذیرفته است. در این تحقیق با نرم‏افزار اجزای محدود آباکوس دالهای یک‌طرفه و دوطرفه بتنی مدل شدهاند و تحلیل دینامیکی به روش تاریخچه زمانی از نوع گام به گام صریح انجام شد. برای بتن مدل غیرخطی خرابی پلاستیک و برای فولاد و تاندونهای پیشتنیدگی مدل خطی بکار گرفته شد. بارگذاری انفجاری به روش تجربی و با استفاده از مدل CONWEP به نمونههای دال اعمال گردید و شرایط مرزی آزاد، مفصلی برای لبههای دالهای مورد بررسی تعریف گردید. نتایج حاصل نشان داد رفتار بتن در برابر انفجار، با پیش‏تنیدگی کاملاً بهبود مییابد. البته مقدار بهینه پیش‏تنیدگی و فاصله‏ تاندونها برای بهبود رفتار دال در برابر انفجار با مدل‏سازی‏های بیشتر قابل محاسبه است. نتایج مدل اجزای محدود نشان داد که حداکثر تنش‏ در بتن پیش‏تنیده به سه برابر تنش تجربه‌شده در بتن‏آرمه میرسد. همچنین پیشتنیده کردن دال، خیز حداکثر را حدودcm 3 نسبت به دال بتن‏آرمه کاهش داد. می‏توان به‌طور قطعی گفت که پیش‏تنیدگی مسیری مناسب برای بهبود رفتار دال‏ها در برابر انفجار در استحکامات پدافندی ضد انفجار است. نتایج حاصل از بررسی‏ها نشان می‏دهد که هندسه دال اعم از یک‌طرفه یا دوطرفه بودن آن و موقعیت انفجار بر مقادیر تنش و خیز ناشی از بارگذاری انفجاری تأثیر دارد.

کلیدواژه‌ها

20.1001.1.20086849.1400.12.3.6.6

عنوان مقاله [English]

The Effect of Prestressing on the Dynamic Response of Concrete Slabs under Blast Loading

نویسنده [English]

seyed shahab Emamzadeh

Faculty member , Civil Engineering Department, , Kharazami University, Tehran, Iran

چکیده [English]

This study has been conducted to investigate the ability of prestressed concrete slabs against explosion with passive defense objectives by the structural method. In this research, one-way and two-way concrete slabs have been modeled with Abaqus finite element software. The dynamic analysis has been performed by the explicit step-by-step time history method. The non-linear plastic failure model has been used for the concrete behavior, whilst a linear model has been used for the steel and prestressed tendons. Explosive loading has been applied to the slab samples experimentally using the CONWEP model and free boundary conditions have been defined for the edges of the studied slabs. The results of the finite element model shows that the maximum stress in prestressed concrete reaches three times the stress experienced in the reinforced concrete. Also, prestressing the slab reduces the maximum deformation by about 3 cm compared to the reinforced concrete slab. The results show that the behavior of concrete against explosion is remarkably improved by prestressing. However, the optimal amount of prestressing and the distance of the tendons required to improve the slab behavior against explosion, can be calculated through more modeling. It can be said with certainty that prestressing is a good way to improve the behavior of slabs against explosion in explosion-proof defensive fortifications. The results show that the effect of slab geometry, whether it is one-way or two-way and the location of the explosion, affect the values of stress and deflection due to the explosive load.

کلیدواژه‌ها [English]

Concrete Slab
Prestress
Explosion
Abaqus

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