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رفتار برش منگنه‌ای دال تخت مرکب از بتن‌های معمولی و مواد مرکب سیمانی مهندسی تحت لنگر نامتعادل | ||
| نشریه مهندسی عمران امیرکبیر | ||
| مقاله 24، دوره 53، شماره 10، دی 1400، صفحه 4519-4534 اصل مقاله (3.47 M) | ||
| نوع مقاله: مقاله پژوهشی | ||
| شناسه دیجیتال (DOI): 10.22060/ceej.2020.18378.6865 | ||
| نویسندگان | ||
| محمدرضا اصفهانی* 1؛ محمد امیری2 | ||
| 1عضو هیئت علمی، دانشکده مهندسی، گروه عمران، دانشگاه فردوسی مشهد، ایران | ||
| 2گروه عمران، دانشکده مهندسی، دانشگاه فردوسی مشهد، مشهد، ایران | ||
| چکیده | ||
| ظرفیت باربری و شکل‌پذیری دو خصوصیت مهم اتصال دال تخت - ستون در مناطق لرزه‌خیز است. برای تقویت اتصال در برابر برش منگنه‌ای راهکارهای مختلفی شامل استفاده از سرستون، پهنه، بتن با مقاومت بالا و میلگردگذاری‌های برشی مورد استفاده قرار گرفته است. در این پژوهش آزمایشگاهی اثر استفاده از مواد مرکب سیمانی مهندسی (ECC) با خصوصیاتی نظیر توانایی گسترش انبوه ترک‌ها در اثر بارگذاری، سخت شوندگی کرنشی، مقاومت در برابر نیروی برشی، مقاومت در برابر لایه لایه شدن، قابلیت تغییر شکل زیاد، برای بهبود رفتار مقاومت برشی منگنه‌ای دال‌های تخت تحت لنگر نامتعادل بررسی شد. 7 نمونه آزمایشگاهی دال تخت بتن مسلح با ابعاد 100×1000×1000 میلی‌مترمکعب تحت بار با خروج از مرکزیت 150 میلی‌متر مورد بررسی قرار گرفت. دال‌ها از دو لایه بتن معمولی و ECC در ضخامت آن‌ها ساخته شدند. پارامترهای متغییر شامل اثر لنگر نامتعادل، بهبود سطح تماس دو ماده و ضخامت ECC بودند. مشاهده شد که بهبود سطح تماس بتن معمولی و ECC سبب افزایش ظرفیت برشی می‌شود. همچنین جایگزینی بتن دال با ECC سبب افزایش ظرفیت برش منگنه‌ای و بهبود رفتار پس پانچینگ دال بدون افت زیاد و ناگهانی در بار می‌گردد. تغییر مکانیزم شکست از یک شکست ترد و ناگهانی به سمت شکست شکل‌پذیر با جذب انرژی بالا در هنگام استفاده از ضخامت‌های بیشتر لایه ECC مشاهده شد. | ||
| کلیدواژه‌ها | ||
| مواد مرکب سیمانی مهندسی؛ دال تخت؛ انتقال لنگر؛ اتصال دال - ستون؛ برش منگنه‌ای | ||
| موضوعات | ||
| اتصالات بتنی؛ تست های آزمایشگاهی؛ تکنولوژی بتن؛ دال های بتنی؛ کامپوزیت؛ مصالح نوین جهت اصلاح خواص بتن؛ مقاوم سازی سازه های بتنی؛ مکانیک شکست سازه بتنی | ||
| عنوان مقاله [English] | ||
| Punching shear behavior of flat slabs composed of normal concrete and ECC under the unbalanced moment | ||
| نویسندگان [English] | ||
| Mohammad Amiri2؛ | ||
| 2Civil, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran | ||
| چکیده [English] | ||
| Load capacity and ductility are the two main characteristics of flat slab-column connections in highly seismic areas. To date, different methods have been employed to strengthen the connection against shear punching, including column capital, drop panel, high strength concrete, and shear reinforcement. In the current experimental study, the effect of using Engineered Cementitious Composite (ECC) on upgrading the punching shear strength of flat slabs under an unbalanced moment was investigated. ECC can provide the composite with features such as the ability to spread multiple cracks under load, strain hardening, shear force, scabbing strength, and high deformation. To this end, seven reinforced concrete flat slab specimens with the dimensions of 1000mm*1000mm*100 mm under the load with the eccentricity of 150mm were examined. The slabs were made from two layers of normal concrete and ECC in their thicknesses. The variable parameters included the unbalanced moment effect, improved interaction of the two materials, and ECC thickness. It was observed that improving the contact surface of normal concrete and ECC increased the shear capacity. In addition, the replacement of slab concrete with ECC increases the punching capacity and post-punching strength of the slab without a large and sudden drop in load. The change in failure mechanism was observed from a sudden and abrupt failure to a formable failure with high-energy absorption when using more ECC layer thicknesses. | ||
| کلیدواژه‌ها [English] | ||
| Engineered Cementitious Composite, Flat slab, Moment transfer, Slab-column connection, Punching shear | ||
| مراجع | ||
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