بررسی آزمایشگاهی و عددی تاثیر الیاف فولادی بر رفتار بتن الیافی تحت تنش چند ‌محوری

نوع مقاله : مقاله پژوهشی

نویسندگان

گروه سازه دانشکده عمران، دانشگاه تبریز، تبریز، ایران

چکیده

بتن یکی از پرکاربردترین مصالح ساختمانی در جهان به شمار می‌آید و استفاده از بتن الیافی در سازه‌ها برای افزایش مقاومت کششی و بهبود رفتار آن، در دهه‌های اخیر توسعه زیادی یافته است. برای بررسی عددی رفتار بتن الیافی، باید معادلات ساختاری آن تعیین گردد. این معادلات بایستی شامل روابطی جهت اعمال اثرات الیاف در رفتار بتن الیافی باشد. در این تحقیق، رفتار بتن‌های با الیاف فولادی حاوی مقادیر متفاوت الیاف، تحت فشار سه‌محوری با مقادیر فشار محصور‌کننده متفاوت، به دو صورت تجربی و عددی، بررسی می‌شود. در آزمایش‌های سه‌محوری از سلول هوک استفاده می‌گردد. در بررسی عددی، معادلات ساختاری با معیار گسیختگی پنج پارامتری ویلیام- وارنکه ، تابع سخت‌شدگی و نرم‌شدگی ایزوتروپیک و پلاستیسیته غیر‌همبسته استفاده شده و برای انتگرال‌گیری از معادلات ساختاری، روش انتگرال‌گیری گامک به‌کار می‌رود. برای اعمال اثر الیاف بر سطح تسلیم، ضریبKt  با استفاده از نتایج آزمایش‌های دومحوری روی نمونه‌های بتن با الیاف فولادی تعیین می‌شود. معادلات ساختاری با استفاده از سابروتین UMAT در نرم افزار ABAQUS کد‌نویسی شده و نمونه‌های آزمایشگاهی مدل‌سازی می‌شوند. مقایسه نتایج به‌دست آمده از مدل‌سازی عددی به صورت منحنی تنش-کرنش و مقاومت حداکثر نمونه‌های SFRC با نتایج آزمایشگاهی انطباق قابل قبولی را نشان می‌دهد. در نهایت با توجه به انطباق نتایج عددی و آزمایشگاهی، نتیجه گرفته شد که می توان با اطمینان قابل قبولی از مدل عددی برای پیش بینی رفتار نمونه‌های SFRC استفاده کرد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Experimental and numerical investigation of the effect of steel fiber on fiber reinforced concrete under multiaxial compression

نویسندگان [English]

  • Gholamreza Baghban Golpasand
  • غلامرضا Farzam
  • Siamak Soleymani Shishvan
Department of Structural Engineering, University of Tabriz, Tabriz, Iran
چکیده [English]

Concrete is one of the most widely used building materials in the world and the use of fiber-reinforced concrete (FRC) in structures to increase its tensile strength and improve its behavior has been extensively developed in recent decades. It is necessary to determine the constitutive equations of FRCs when the numerical investigation of their behavior is running. These equations should be including relations to handle the effect of steel fibers on the behavior of FRC. In this study, the behavior of FRCs with a different percent of steel fiber under triaxial compression, with different values of confining pressure, is experimentally and numerically investigated. Hoek cell is used in triaxial tests. In the numerical simulation, five-parametric constitutive equations with Willam-Warnke (W-W) failure criterion, isotropic hardening/softening function and non-associated plasticity were used and substepping integration method was carried out for integration of constitutive equations. For applying the effect of steel fibers on the failure surface, Kt coefficient was determined from the results of biaxial experimental tests on SFRCs. The constitutive equations are implemented with UMAT subroutine in ABAQUS and specimens are simulated in ABAQUS. By the comparison of the experimental (maximum strength) results and the numerical (stress-strain curve) results, an acceptable agreement was seen between them. Finally, based on the consistency between experimental and numerical results, it was concluded that the numerical model could be used, with enough confidence, to predict the behavior of SFRCs specimens.

کلیدواژه‌ها [English]

  • Steel fiber reinforced concrete (SFRC)
  • Constitutive equations
  • Triaxial Test
  • Substepping integration
  • non-associated plasticity
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