مطالعه آزمایشگاهی و عددی رفتار مهاربند کمانش ناپذیر با غلاف ترکیبی فولادی و پلی آمید

نوع مقاله : علمی - پژوهشی

نویسندگان

1 دانشیار، دانشگاه سمنان، سمنان، ایران

2 دانشجوی دکترای سازه دانشگاه سمنان

3 فارغ التحصیل کارشناسی ارشد دانشگاه سمنان

4 استادیار، دانشگاه سمنان، سمنان، ایران

چکیده

یکی از سیستم‌های پرکاربرد مقاوم در برابر بارهای جانبی در طراحی و مقاوم‌سازی سازه‌های بتنی و فولادی‌، مهاربند فولادی است. یکی از روش‌های ابداع شده توسط محققان، استفاده از اعضای محصور کننده برای جلوگیری از کمانش کلی مهاربند و کاهش اثرات ناشی از آن است. در این سیستم مهاربندی که به "مهاربند کمانش‌ناپذیر" موسوم است، بار محوری توسط هسته مهاربند تحمل شده و با استفاده از یک غلاف محصور کننده از کمانش کلی آن جلوگیری می‌شود. در این مقاله مطالعه آزمایشگاهی و عددی اثرات ناشی از نوع فولاد هسته و فاصله هسته از غلاف بر رفتار مهاربند کمانش‌ناپذیر مورد بررسی قرار گرفته است. مدل‌های آزمایشگاهی شامل شش مهاربند با هسته‌ای از جنس فولاد ST37 معمولی و ST37-n (نرم شده در دمای 1000 درجه به روش اونیل) است که در آن‌ها فاصله هسته از غلاف برابر صفر، دو و سه میلی‌متر است. نتایج آزمایشگاهی نشان می دهد که استفاده از فولاد نرم‌تر با تنش تسلیم پایین‌تر و با ضخامت برابر در هسته موجب کاهش ظرفیت باربری و مقاومت مهاربند می گردد. اما مهاربند در تغییرمکان‌های کوچکتری شروع به اتلاف انرژی کرده است. افزایش فاصله هسته از غلاف نیز موجب کاهش ظرفیت باربری و استهلاک انرژی مهاربند می گردد. همچنین افزایش فاصله هسته از غلاف به بیش از 2 میلی‌متر، موجب از بین رفتن تقارن و پایداری رفتار هیسترزیس مهاربند شده و اعوجاج‌های ناشی از کمانش موضعی مهاربند در فشار، شدت بیشتری می یابد. ماده پرکننده پلی‌آمید در برابر فشارهای وارده از طرف هسته مقاومت مناسبی داشته و دچار هیچ‌گونه خرابی خاصی نشده است. بنابراین با توجه به دارا بودن وزن مخصوص کمتر می‌تواند جایگزین مناسبی برای بتن باشد و وزن کلی مهاربند را کاهش دهد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Experimental and Numerical Study of Buckling Restrained Bracing Behavior with Combined Steel and Polyamide Sheath

نویسندگان [English]

  • Madjid Gholhaki 1
  • Ghasem Pachideh 2
  • Rahim Lashgari 3
  • Omid Rezayfar 4
1 Associate Professor, Faculty of Civil Engineering, Semnan University, Semnan, Iran
2 Semnan University
3 Semnan University
4 Assisstant Proffessor, Faculty of Civil Engineering, Semnan University, Semnan, Iran
چکیده [English]

One of the most widely used system resisting against lateral loads in the design and retrofit of concrete and steel structures is steel bracing. One of the methods developed by the researchers is the use of confining members to prevent general buckling of bracing and reducing the effects of it. In this bracing system known as "Buckling Restrained Bracing, the axial load is born by bracing core and by using surrounding sheath, its overall buckling can be avoided. In this paper, experimental and numerical study of the effects caused by steel type of core of the distance of core from sheath on buckling restrained bracing was studied. Experimental models consist of six bracings with core of conventional ST37 and ST37-n steel (softened at a temperature of 1000 degrees by O'Neill method), in which the distance of core from sheath is zero, two, and three mm. Experimental results show that the use of softer steel with lower yield stress and with equal thickness in the core reduces bearing capacity and resistance or strength of bracing. However, bracing in smaller displacements started to energy waste. Increasing distance of the core from sheath also reduces bearing capacity and energy dissipation of bracing. In addition, increasing the distance of core from sheath to more than 2 mm causes the loss of symmetry and stability in hysteresis behavior of bracing and distortions resulting from local buckling in the bracing in pressure were intensified. Polyamide filler material had good resistance against pressure from the core and no certain damage was seen in it. Therefore, due to having less specific gravity, it could be a good alternative to concrete and reduce the overall weight of the bracing.

کلیدواژه‌ها [English]

  • Buckling Restrained Bracing
  • steel sheath
  • polyamide sheath
  • distance of core from sheath
  • strenght
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