ارائه روش جدید مبتنی بر نمودار برای طراحی برشی ورق‌های فولادی در دماهای بالا

نوع مقاله : مقاله پژوهشی

نویسندگان

1 گروه مهندسی عمران، دانشگاه شهید مدنی آذربایجان، تبریز، ایران

2 دانشکده مهندسی عمران، دانشگاه تبریز، تبریز، ایران

3 گروه مهندسی عمران، واحد ایالم، دانشگاه آزاد اسالمی، ایلام، ایران.

چکیده

افزایش استفاده از ورق­‌های جدار نازک، لزوم بررسی عمیق­تر رفتار این اعضا را نشان می­‌دهد. با توجه به هزینه قابل توجه انجام کارهای آزمایشگاهی و از طرفی عدم دسترسی همیشگی به نرم­‌افزارهای شبیه­‌سازی عددی پیشرفته نظیر آباکوس، انسیس و...، نیاز به وجود روش طراحی ساده جهت ارزیابی مقاومت برشی ورق­‌ها احساس می‌­شود. این نیاز در دماهای بالا با توجه به تغییر مد خرابی برشی ورق فولادی در برابر حرارت بیش از پیش خود را نشان می‌­دهد. در این مقاله، روابط طراحی برشی آیین‌­نامه فولاد و پل آمریکا به کمک ضرایب کاهشی آیین­‌نامه اروپا برای استفاده در دماهای بالا اصلاح شده و روابط و نمودارهای طراحی جهت تخمین مقاومت برشی نهایی و دمای متناظر با لحظه خرابی انواع ورق (سخت ­شده و سخت ­نشده) با شرایط مرزی مختلف با در نظرگرفتن تغییر مد خرابی پیشنهاد شده است. مطابق نتایج، نمودارهای پیشنهادی در هر دو دمای محیط و دمای بالا در ورق­های فشرده دارای دقت بیشتری نسبت به ورق‌­های غیرفشرده و لاغر هستند. بدین ترتیب که حداکثر اختلاف بین نتایج نمودارهای پیشنهادی و نتایج شبیه­‌سازی اجزاء محدود مقاله حاضر در دمای محیط در ورق‌های فشرده، غیرفشرده و لاغر به ترتیب به حدود 1/1%، 23% و 28% می­رسد. از طرفی نمودارهای پیشنهادی در دمای 400 و 600 درجه سانتی‌گراد تقریبا با حفظ دقت خود در محدوده ورق­های فشرده، در تخمین مقاومت برشی ورق­‌های غیرفشرده و لاغر منجر به خطایی در حدود 3% تا 11% می­‌شوند. همچنین، حداکثر خطا در مقایسه با نتایج آزمایشگاهی و عددی سایر محققین به ترتیب به حدود 20% و 4% محدود می‌­شود.
 

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Introducing a Novel Diagram-Based Method for Shear Design of Steel Plates at High Temperatures

نویسندگان [English]

  • Abbas Ghadami 1
  • Ghazaleh Pourmoosavi 2
  • Ali Ghamari 3
1 Assistant Professor, Dept. of Civil Engineering, Azarbaijan Shahid Madani University, Tabriz, Iran
2 Post Doc. Researcher, School of Civil Engineering, University of Tabriz, Tabriz, Iran
3 Post Doc. Researcher, Dept. of Civil Engineering, Sharif University of Technology, Tehran, Iran
چکیده [English]

It seems necessary to develop a simplified design approach in order to evaluate the shear strength of web panels under fire condition as the size of furnaces is limited, the cost of experiments aimed at testing the fire resistance of structures is quite high and access to simulation software packages such as ANSYS and ABAQUS is not always guaranteed. In this paper, web panel shear design relationships of AISC360-16 and AASHTO-14 specifications are exploited to be used in fire conditions. To this end, the stress-strain reduction factors provided in EN 1993-1-2 are directly applied. Afterward, the design curves are proposed for the prediction of the ultimate shear strength and limiting temperature of steel plate girders under fire by taking into account the strength degradation caused by high temperatures and the effects due to sectional instability. According to the results, the proposed curves are more accurate in compact plates with plastic shear buckling at both ambient and high temperatures. However, by increasing the web slenderness, the difference is increased. At ambient temperatures, the maximum difference for compact, non-compact, and slender web plates is about 1.1%, 23%, and 28%, respectively. The difference at 400ºC reaches almost 3% and 7% for non-compact and slender web panels, respectively. In addition, at 600ºC, especially for slender plates, proposed curves yield values that are nonconservative for ultimate shear strength, such that the difference is about 11%. Also, the maximum difference for existing experimental and numerical studies is about 20% and 4%, respectively.

کلیدواژه‌ها [English]

  • Fire
  • Plate slenderness
  • Pteel plate girder
  • Shear strength
  • Design diagram
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