بهبود رفتار چرخه ای قاب های فاقد استاندارد لرزه ای بتن آرمه با استفاده از ورق های FRP

نوع مقاله : مقاله پژوهشی

نویسنده

استادیار، گروه مهندسی عمران، واحد سمنان، دانشگاه آزاد اسلامی، سمنان، ایران

10.22124/jcr.2023.23628.1610

چکیده

هدف این مقاله ارزیابی رفتار قاب های بتن آرمه آسیب پذیر(فاقد جزئیات لرزه ای)، بهسازی شده با روش تقویت برشی و خمشی اتصالات تیر-ستون با استفاده از ورق های FRP است. به این منظور در فاز اول تحقیق، با توجه به تمرکز عمده مطالعات پیشین بر اتصالات دو بعدی و عدم درنظرگرفتن شرایط واقعی شامل اثر دال و تیر عرضی در اتصالات، در راستای اعمال شرایط هندسی و محدودیت های اجرایی، دراین تحقیق رفتار اتصالات با اثر دال و تیر عرضی، از طریق مطالعه آزمایشگاهی استخراج شده است. به این منظور 2 نمونه آزمایشگاهی اتصال خارجی تیر-ستون بتنی با مقیاس 2/1 ساخته شده و تحت بارگذاری سیکلی با دامنه افزایشی واقع شده اند. نمونه ها شامل یک نمونه کنترلی بدون جزئیات لرزه ای ویژه و یک نمونه دیگر شامل اتصال فاقدجزئیات لرزه ای است که با ورق های FRP بهسازی شده است. در فاز دوم تحقیق، رفتار اتصالات، قاب های 5 و 10 طبقه کنترلی و بهسازی شده در نرم افزار OpenSees مدل سازی شده و رفتار چرخه ای، شکل پذیری و استهلاک انرژی تمامی قاب ها مورد بررسی قرار گرفته است. نتایج رفتار اتصالات و قاب های بهسازی شده، نشان دهنده عدم افت مقاومت، رفتار پایدار چرخه ای، کاهش اثرات پینچینگ، بهبود سختی و ظرفیت شکل پذیری ناشی ازتغییر مود رفتاری از شکست برشی اتصالات به تشکیل مفاصل پلاستیک خمشی در تیرها، بوده است.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Improving the cyclic behavior of reinforced concrete non-standard seismic frames using FRP sheets

نویسنده [English]

  • MOHAMMAD HOSSEIN SAGHAFI
Assistant Professor, Department of Civil Engineering, Semnan Branch, Islamic Azad University, Semnan, Iran
چکیده [English]

The purpose of this paper is to evaluate the behavior of vulnerable joints of substandard RC frames, improved by Shear and flexural retrofit of beam-column joints using FRP sheets. For this purpose, the behavior of the retrofitted joints is compared with the control joints with and without special seismic details. Considering the main focus of previous studies on two-dimensional joints and not considering the real conditions including the effect of slab and transverse beam in the joints, in order to apply geometric conditions and constructional limitations, in this study the behavior of joints with slab and transverse beam effect has been extracted by experimental study. For this purpose, 2 experimental specimens of concrete exterior beam-column joint with a scale of 1/2 are made and subjected to a cyclic load. The specimens include one control specimen, without special seismic details, and the other retrofitted specimen include a joint without seismic detail, which has been improved with FRP sheets. Finally, the studied joints were modeled using OpenSees software and compared with the experimental results of the research. The results of the retrofitted joint behavior show no strength drop, stable cyclic behavior, reduced pinching effects, improved cyclic behavior due to change of the failure mode from shear failure of the joints to the formation of flexural plastic hinges in the beam. This performance can be attributed to the effectiveness of the proposed retrofit methods in promoting the behavior of vulnerable joints with real geometric conditions

کلیدواژه‌ها [English]

  • Cyclic curve
  • beam-column external connections
  • transverse beam and slab effect
  • numerical modeling
  • incremental nonlinear analysis

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