ارزیابی عملکرد سازه های قاب خمشی فولادی ,ویژه در برابر حریق

نوع مقاله : علمی - پژوهشی

نویسندگان

1 استادیار/دانشکده فنی و مهندسی/دانشگاه آزاد اسلامی واحد تهران مرکزی

2 کارشناس ارشد سازه، دانشکده فنی و مهندسی، دانشگاه آزاد اسلامی واحد تهران مرکزی، تهران، ایران

چکیده

سازه‌های فولادی در برابر آتش آسیب‌پذیر می‌باشند و با افزایش دما، مشخصات مصالح نظیر مدول الاستیسیته، مقاومت نهایی و مقاومت تسلیم تغییر خواهند نمود. در این مقاله اثر حریق بر عملکرد قاب‌های خمشی فولادی وی‍ژه مورد بررسی قرار می‌گیرد. بدین منظور، سناریوهای مختلف نظیر تغییر موقعیت حریق در دهانه‌ها و طبقات مختلف، مورد بررسی قرار گرفت. آنالیز حرارتی و تحلیل غیرخطی و در نهایت بررسی عملکرد سازه‌ها با استفاده از مصالح فولادی حرارتی اصلاح شده، انجام گردید. نتایج حاصل شده حاکی است که آتش سوزی‌ در دهانه خارجی ساختمان، وضعیتی بحرانی را بوجود خواهد آورد. روند تغییرات نسبت بارهای فروریزش به بارهای طراحی، به محض رسیدن به درجه حرارت 300 درجه سانتی‌گراد، متفاوت است. در موقعیت‌های مختلف آتش‌سوزی و در دماهای پایین تر از 300 درجه سانتی‌گراد، میزان افزایش بارهای فروریزش در مقایسه با بارهای طراحی تقریباً 25 درصد می‌باشد. در حالی‌که در دماهای بالاتر از 300 درجه سانتی‌گراد، با توجه به موقعیت قرارگیری آتش، میزان افزایش یادشده به 60 درصد نیز خواهد رسید. روند تغییرات بار فروریزش تحت دماهای بالا و موقعیت‌های مختلف آتش‌سوزی به‌گونه‌ای است که به مقدار مشخصی همگرا می‌شود. بر اساس نتایج حاصله از تحلیل‌های غیرخطی، راهکاری پیشنهادی جهت پیش‌بینی بار فروریزش قاب‌های فولادی تحت شرایط آتش‌سوزی ارائه گردید

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Evaluation of the performance of special steel moment frames under fire conditions

نویسندگان [English]

  • Abbas Ghasemi 1
  • Hadi Mirzaei 2
1 Assistant Professor/ Faculty of Technology and Engineering/ Islamic Azad University Central Tehran Branch
2 Master of Structures, Faculty of Engineering, Islamic Azad University, Central Tehran Branch, Tehran, Iran
چکیده [English]

Steel structures are vulnerable to fire and material properties such as modulus of elasticity, ultimate strength and yield strength will change with increasing temperature. In this study, the effect of fire on the performance of special steel moment frames is investigated. For this purpose, different scenarios such as changing the location of the fire in different bays and floors were considered. Thermal analysis and nonlinear analysis and finally the performance of the structures were performed using modified thermal steel materials. The results indicate that the fire in the outer opening of the building will create a critical situation. the performance of the structures was evaluated based on the thermal analysis and using the modified thermal steel material. The results indicated that the fire in the exterior bays will be a critical situation. The variation trend of the ratio of collapse loads to design loads as soon as the temperature reaches 300 ° C is different. In different locations and at temperatures below 300 ° C, The increase rate of collapse loads to design loads is approximately 25%. While at temperatures above 300 ° C, with regard to the fire location, the rate of increase will reach 60%. The trend of collapse load variations under high temperatures and different fire locations is such that it converges to a certain value. Based on the results of nonlinear analysis, a design procedure was proposed to predict the collapse load of steel frames under fire conditions.

کلیدواژه‌ها [English]

  • Fire
  • performance
  • Special
  • Steel
  • moment frames
  • collapse loading
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