ارزيابي‌ عددي اثر كامپوزيت‌هاي پليمري (FRPS) در تقويت دال بتن‌آرمه در معرض انفجارارزيابي‌ عددي اثر كامپوزيت‌هاي پليمري (FRPS) در تقويت دال بتن‌آرمه در معرض انفجارارزيابي‌ عددي اثر كامپوزيت‌هاي پليمري

Numerical Evaluation of the Retrofit Effectiveness for Fiber Reinforced Polymers (FRPS) Retrofitted Concrete Slab Subjected to Blast Loading

يكي از راه هاي تقويت المان هاي سازه اي تحت انفجار، استفاده از مصالح با شكل پذيري و مقاومت بالا مانند كامپوزيت هاي پليمري مسلح شده (FRPS) است. بررسي تاثير تقويت المان ها، با انجام آزمايش و تحليل پاسخ نمونه تحت انفجار انجام مي شود. در اين مطالعه به تحليل ديناميكي غير خطي نمونه دال هاي مسلح شده با كامپوزيت هاي FRP، تحت بارهاي انفجاري پرداخته شده است. براي مدل سازي نمونه ها و بارگذاري از نرم‌افزار LS-DYNA استفاده شده و نتايج تحليل با نتايج آزمايشگاهي موجود مقايسه شده است كه سازگاري پاسخ عددي نرم‌افزار و آزمايش به دست آمده است. به طور كلي نمونه هاي تقويت شده با كامپوزيت نسبت به نمونه هاي فاقد تقويت پاسخ بهتري در مقابل آزمايش‌هاي انفجاري داشته اند. همچنين دراينجا مطالعات پارامتري براي بررسي حد تاثير هر كدام از پارامترهاي ضخامت ورقه‌ي كامپوزيت، مقاومت كامپوزيت، مقاومت فشاري بتن و درصد ميلگردهاي فولادي به طور مستقل صورت گرفته است. افزايش مقاومت فشاري بتن نسبت به افزايش ساير پارامترها تاثير بيشتري در بهبود پاسخ نمونه تحت انفجار داشته و به عبارتي مقرون به صرفه تر است. براي بررسي مقاومت كامپوزيت در پاسخ نمونه تقويت شده، با ثابت نگه داشتن همه مشخصات نمونه و تنها با تغيير نوع كامپوزيت، از دو نوع كامپوزيت پليمري كربن (CFRP) و كامپوزيت پليمري شيشه (GFRP) استفاده شده است. نتايج نشان مي دهد كه با توجه به اين كه مقاومت طولي كامپوزيت هاي الياف كربن نسبت به الياف شيشه بالاتر است، در نتيجه بهبود در عملكرد نمونه-هاي مسلح شده به كامپوزيت CFRP نسبت به GFRP بيشتر حاصل شده است.

For retrofitting structures against blast loads, sufficient ductility and strength should be provided by Using high-performance materials such as fiber reinforced polymer (FRP) composites. The effectiveness of retrofit materials needs to be precisely evaluated for the retrofitting design based on the dynamic material responses under blast loads. The structural behavior of reinforced concrete (RC) slab retrofitted with fiber reinforced polymer (FRP) under blast pressure is simulated using nonlinear transient analysis of Ls-Dyna software. And the analysis results are verified with the previous experimental results. It was determined that overall the FRP retrofitted panels performed better than the companion control panels. Parametric studies are performed to examine the influence of FRP thickness, FRP strength, Compressive strength of concrete, ratio of steel bars on the response of retrofitted panel. Improvement on slab blast load resistance capacity is achieved by increasing all of parameters. But effect of increasing Compressive strength of concrete is more than another, In other words, increasing Compressive strength of concrete is economical. The relative effectiveness of CFRP and GFRP in strengthening deficient slabs can be evaluated by comparing the behavior of specimens. The two slabs in each set of specimens are similar in every aspect except that one slab was retrofitted by CFRP whereas the other one was confined by GFRP. The layers of the GFRP were as those of the CFRP. Comparisons of the ductility parameters show that both slabs in each set behaved in a similar manner and had comparable ductility parameters, the ultimate tensile strength of the CFRP fabric was higher than that of the GFRP fabric. The effectiveness of CFRP measured was larger than that of GFRP. From these test results, it appears that the effectiveness of FRP in enhancing slab ductility closely relates to its ultimate tensile strength..For retrofitting structures against blast loads, sufficient ductility and strength should be provided by Using high-performance materials such as fiber reinforced polymer (FRP) composites. The effectiveness of retrofit materials needs to be precisely evaluated for the retrofitting design based on the dynamic material responses under blast loads.The structural behavior of reinforced concrete (RC) slab retrofitted with fiber reinforced polymer (FRP) under blast pressure is simulated using nonlinear transient analysis of Ls-Dyna software. And the analysis results are verified with the previous experimental results. It was determined that overall the FRP retrofitted panels performed better than the companion control panels. Parametric studies are performed to examine the influence of FRP thickness, FRP strength, Compressive strength of concrete, ratio of steel bars on the response of retrofitted panel. Improvement on slab blast load resistance capacity is achieved by increasing all of parameters. But effect of increasing Compressive strength of concrete is more than another, In other words, increasing Compressive strength of concrete is economical. The relative effectiveness of CFRP and GFRP in strengthening deficient slabs can be evaluated by comparing the behavior of specimens.