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ظرفیت برش پانچینگ دال بتنی دو طرفه با الیاف فولادی
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نویسنده
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خواجه محمودآبادی امیرمحمد ,اصفهانی محمدرضا
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منبع
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مهندسي عمران شريف - 1398 - دوره : 35-2 - شماره : 3/1 - صفحه:91 -97
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چکیده
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هدف از انجام پژوهش حاضر، بررسی افزایش مقاومت برشی پانچینگ دال‌های تخت دوطرفه با استفاده از الیاف فولادی است. یکی از مشکل‌های موجود در دال‌های تخت، پدیده‌ی برش پانچینگ است و این پدیده در دال‌های با ضخامت کم که امکان اجرای خاموت وجود ندارد، جدی‌تر می‌شود. با افزودن الیاف می‌توان این مشکل را برطرف کرد. در نوشتار حاضر، 8 نمونه دال مربعی با ابعاد $1000times{1000}times{100}$ میلی‌متر ساخته و آزمایش شده است. پارامترهای متغیر در این دال‌ها درصد الیاف و درصد آرماتور کششی است. درصد الیاف به کار رفته در پژوهش حاضر شامل 0٫5، 1 و 1٫5 درصد و نسبت آرماتورهای خمشی استفاده‌شده 0٫45٪ و 1٫02٪ است. از جمله نتایج مهم پژوهش حاضر اینکه افزودن 1٫5٪ الیاف بسته به نسبت آرماتور موجب افزایش 34 و 64 درصدی ظرفیت برش پانچینگ می‌شود.
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کلیدواژه
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بتن الیافی، ظرفیت برش پانچینگ، دال تخت
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آدرس
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دانشگاه فردوسی مشهد, دانشکده مهندسی عمران, ایران, دانشگاه فردوسی مشهد, دانشکده ی مهندسی عمران, ایران
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پست الکترونیکی
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esfahani@um.ac.ir
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PUNCHING SHEAR STRENGTH OF STEEL FIBERREINFORCED CONCRETE TWOWAY SLABS
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Authors
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khaje mahmoud abadi A.M
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Abstract
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Concrete is a brittle material with a low strain capacity. The addition of randomly distributed discrete fibers in concrete significantly improves the flexural behavior of structural concrete elements because of its enhanced tensile properties and crack control. In this paper, an experimental program was carried out to study the punching shear strength of flat slabs reinforced with steel fibers. The addition of steel fibers generally contributes to the improvement of punching shear strength of flat slabs. The experimental work consisted of 8 rectangular specimens measuring 100 mm in depth, 1000 mm in length, and 1000 mm in width, six of which consisted of hookedend steel fibers. The concrete mixtures were cast using ordinary Portland cement with a watercement ratio of 0.41. During the punching shear tests, the load and the maximum deflection were recorded on a computerized data recording system; as a result, the loaddisplacement curve was drawn. The main variables considered include the volume fraction of steel fibers as well as the steel bar reinforcement ratio. The fibers were used at the volume fractions of 0.5%, 1%, and 1.5%, and the reinforcement ratios of the slabs were 0.45% and 1.02%. After 28 days of curing, all the specimens were tested. The objective of this study is to investigate the modes of failure, the loaddeflection relationships, and the effectiveness of adding steel fibers to flat slabs. Based on the results of this study, it was concluded that adding 1.5% of steel fibers improved punching shear strength up to 34% and 64% depending on the ratio of reinforcement. In addition, it was shown that the depth of the flat slabs could decrease up to 38% and 40% in comparison to the slabs with plain concrete. Furthermore, increasing the ratio of reinforcement from 0.45% to 1.02% led to the enhancement of punching shear strength and improved toughness. The test results indicated that with fiber volume fractions of 0.5, 1, and 1.5, the shear punching strength increased by 49%, 30%, and 23% due to the enhancement of flexural reinforcement from 0.45% to 1.02%, respectively.
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Keywords
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