مهندسی سازه و ساخت

مهندسی سازه و ساخت

بررسی آزمایشگاهی و عددی رفتار چرخه‌ای تیرهای بتن‌آرمه با استفاده از سیستم ضد کمانش ورق فولادی دورگیر در محل مفصل پلاستیک

نوع مقاله : علمی - پژوهشی

نویسندگان
1 دانشجوی دکتری، مهندسی سازه، گروه مهندسی عمران، پردیس بین الملل دانشگاه ارومیه، ارومیه، ایران
2 استاد، دانشکده فنی و مهندسی، گروه مهندسی عمران، دانشگاه ارومیه، ارومیه، ایران
چکیده
در قاب‌های خمشی بتن‌آرمه، در محل مفصل پلاستیک تیرهای بتنی، بیشترین تغییر شکل‌های موردنیاز سازه تأمین می‌شود و به همین دلیل است که همواره در آیین‌نامه‌های مختلف طراحی لرزه‌ای، ضوابط بسیار سخت‌گیرانه‌ای در مورد فاصله بین آرماتورهای عرضی در نظر گرفته‌شده است که اجرا و بتن‌ریزی در این نواحی را به دلیل ازدیاد آرماتور دچار مشکل می‌کند. در محل مفصل پلاستیک تیرهای بتنی با ارتفاع زیاد، به دلیل ازدیاد نیاز کرنشی آرماتورهای طولی، آرماتورهای با قطرکم تحت بارهای چرخه‌ای، دچار کمانش شده و به‌صورت خستگی تحت کمانش بارهای چرخه‌ای کوتاه، گسیخته می‌شوند. در این پژوهش، با معرفی یک سیستم جدید برای استفاده در محل مفصل پلاستیک تیرهای بتن مسلح، سعی داشتیم تا مشکلات مطرح‌شده در مفصل پلاستیک سازه‌های بتنی را حل‌وفصل کنیم. بررسی‌های انجام‌شده در این تحقیق، هم به‌صورت آزمایشگاهی و هم به‌صورت عددی بوده که در ابعاد واقعی و تحت بار چرخه‌ای، در نظر گرفته‌شده است. در سیستم معرفی‌شده جدید در محل مفصل پلاستیک، با استفاده از دو ورق فولادی خم و سوراخ‌کاری شده، یک سیستم مهاری برای آرماتورهای طولی ساخته‌شده است که هم بتواند یک محصورشدگی مناسب برای کمانش آرماتورهای طولی در ناحیه مفصل پلاستیک باشد، و هم با افزایش محصورشدگی بتن هسته مرکزی تیر، شکل‌پذیری سیستم را افزایش دهد. نمونه‌های آزمایشگاهی تعداد 2 نمونه 5 متری بوده که نمونه اول، بدون ورق دورگیر فولادی و به‌صورت معمولی طراحی و ساخت شده است ولی در نمونه دوم، از سیستم ضد کمانش ورق دورگیر کننده استفاده‌شده است. با مشاهده نتایج آزمایش‌های تجربی و عددی، می‌توان به این نتیجه رسید که با استفاده از ورق فولادی در محل مفصل پلاستیک، از کمانش آرماتورهای طولی به‌صورت کلی در جهت خارج از تیر، جلوگیری شده است. همچنین با تحلیل مدل‌های عددی با استفاده از نرم‌افزار اجزا محدود LS-Dyna، عملکرد مثبت این سیستم بررسی‌شده است.
کلیدواژه‌ها

موضوعات


عنوان مقاله English

Experimental and Numerical Investigation of Cyclic Behavior of RC Beams Using Anti-buckling System of Wrapped Steel Sheet in Plastic Hinge Region

نویسندگان English

Amir Jabbari 1
Saeed Tariverdilo 2
Mohammad Reza Sheidaii 2
1 PhD Student, Structural Engineering, Department of Civil Engineering, Urmia University International Campus, Urmia, Iran
2 Professor, Engineering Faculty, Civil Engineering Department, Urmia University, Urmia, Iran
چکیده English

In reinforced concrete moment frames, the plastic hinge regions of concrete beams provide most of the demanded deformations of the structure. That is why there are always strict rules regarding the distance between transverse reinforcements in different seismic design regulations, which makes them difficult to implement in the construction process. In the plastic hinge regions of the concrete beams with high heights, the main rebars with low diameter are prone to buckling under the effect of a low number of cyclic loads, which we know as low cycle fatigue. In this study, we introduced a new system to prevent the buckling of longitudinal reinforcements in the plastic hinges. Experimental and numerical studies were conducted on full-scale specimens with cyclic loading. The new system employs two bent steel sheets to prevent the buckling of longitudinal reinforcements and to improve the lateral restraint and ductility of the plastic hinge by confining the concrete core of the beam. The laboratory samples were two 5-meter specimens. Unlike the first sample, the second one used the anti-buckling system of the perforated sheet. The showed that the steel plate prevented the longitudinal reinforcement from buckling outward in the plastic hinges. The numerical models were analyzed using finite element software LS-Dyna, which confirmed the positive performance of this system.

کلیدواژه‌ها English

Buckling
Reinforced Concrete Beam
Plastic Hinge
Cyclic Behavior
Longitudinal Rebars
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  • تاریخ دریافت 12 مرداد 1402
  • تاریخ بازنگری 16 مهر 1402
  • تاریخ پذیرش 26 آبان 1402