بهبود رفتار چرخه‌ای قاب‌های فولادی دارای ستون‌های CFT با استفاده از مهاربند و میراگرهای اصطکاکی دورانی

نوع مقاله : پژوهشی اصیل (کامل)

نویسندگان
احمد ملکی 1
علی ستاری 2
محمد علی لطف اللهی 3
1 هیات علمی دانشگاه آزاد اسلامی واحد مراغه
2 دانشجوی دکتری دانشگاه آزاد اسلامی واحد مراغه
3 هیات علمی دانشکده مهندسی عمران دانشگاه تبریز
چکیده
میراگرهای اصطکاکی دورانی، نوع خاصی از میراگرهای اصطکاکی هستند که دارای مزایای متعدد می‏باشند. میراگرها به منظور بهبود رفتار چرخه‏ای سازه‏ها در برابر بارهای ناشی از باد و زلزله مورد استفاده قرار می‏گیرند، این نوع میراگرها با دوران و باز دوران خود موجب استهلاک انرژی می‏شوند. در این تحقیق، به بررسی مقدار جابجایی و برش پایه سازه قاب‏های فولادی با ستون‏های پُرشده با بتن(CFT) در دو حالت سازه مهاربند‏ی شده همراه با میراگرهای اصطکاکی‏دورانی و سازه بدون مهاربند و میراگرهای اصطکاکی‏دورانی پرداخته‏شده‏است. قاب‏ مرکب فولادی (با ستون‏های CFT) مهاربندی شده تحت اثر رکورد یازده زلزله حوزه نزدیک، در نرم‏افزار ETABS مدل سازی، تحلیل و طراحی شده‏است. استفاده از مهاربند به همراه میراگراصطکاکی‏دورانی، جابجایی مرکز جرم بام سازه را تحت‏اثر یازده رکورد زلزله مورد بحث در نرم‏افزاراجزاء محدود ETABS برای نه رکورد نسبت به حالت بدون میراگر بین 13 تا 49 درصد کاهش و برای دو رکورد افزابشی بین 2 تا 17 درصد داشته‏است. استفاده از مهاربند به همراه میراگرهای‏اصطکاکی‏دورانی برای هشت رکورد باعث کاهش برش پایه سازه‏ به میزان 11 تا 37 درصد شده است. و در سه رکورد باعث افزایش برش‏پایه به میزان 3 تا 26 درصد شده است.

سپس یک‏ قاب‏ یک دهانه یک طبقه با همان مصالح و مشخصات در نرم‏افزاراجزاء محدود ABAQUSمدل سازی گردیده است. برای بارگذاری جانبی ستون‏ها از پروتکل بارگذاری جانبی بر اساس ATC-24 و دستورالعمل استفاده از میراگرها در طراحی و مقاوم سازی ساختمان‏ها استفاده شده است. با توجه به ضابطه شماره 766 سازمان برنامه و بودجه برای جابجایی ایجاده شده در اثر رکورد یازده زلزله معرفی شده در نرم‏افزار ETABS ازسیکل‏های بارگذاری با فرکانس معادل 1.15T در نرم‏افزار‏اجزاء محدود ABAQUS استفاده شده است. استفاده از مهاربند و میراگراصطکاکی‏دورانی در نرم‏افزار‏اجزاء محدود ABAQUS تحت اثرهریک از رکوردهای مورد بحث جابجایی سازه‏ را نسبت به سازه بدون مهاربند و بدون میراگر اصطکاکی دورانی به مقدار 16 تا 33 درصد کاهش داده است. استفاده از مهاربند به همراه میراگراصطکاکی‏دورانی در نرم‏افزار‏اجزاء محدود ABAQUS تحت اثرهر یک از رکوردهای مورد بحث باعث‏ کاهش برش پایه شده‏است. مقدار کاهش نیرو برای رکورد زلزله‏های مورد بحث یکسان نبوده و این مقدار از 8 تا 34.7 درصد متغیر بوده است. نمودارهای هیسترزیس برش پایه سازه‏های مهاربندی شده را در دوحالت سازه با میراگر و بدون میراگر را به خوبی نشان داده‏اند.

کلیدواژه‌ها

موضوعات

عنوان مقاله English

Improved Cyclic Behaviour of Concrete Filled Tube (CFT) Using Rotational Friction dampers and bracing

نویسندگان English

ahmah maleki 1
ali sattari 2
Mohammad Ali Lotfollahi Yaghin 3
1 Faculty of islamic Azad University Maragheh Branch
2 PhD student
3 Professor of Civil Engineering, University of Tabriz
چکیده English

Abstract
Rotational friction dampers are a specific type of friction dampers which have several advantages. Dampers are used to improve the cyclic behavior of structures against forces caused by wind and earthquake. These types of dampers will cause energy dissipation by its rotating and rerotating. However, complete and comprehensive researches have not been performed on the effect of rotational friction dampers and their effect on the bearing capacity of steel frames. In this research, the behavior of concrete-filled steel tube (CFT) in two cases frame braced with rotational friction dampers and frame braced without rotational friction dampers is investigated. For verification, the results obtained from finite element method software, ABAQUS, were compared with that of experimental studies for test samples used in a building with a height of 300m in Osaka, Japan. The hysteresis curves of the modeled samples are in good agreement with the experimental results.


In order to investigate the performance of steel composite frame (with CFTs) braced with rotational friction dampers towards to steel composite frame (with CFTs) braced without rotational friction dampers under the effect of three earthquake Far-field records, the structure was modeled, designed and analyzed in ETABS software. The use of bracing with rotational friction dampers has caused a decrease in the displacement of the roof’s center of mass for each record mentioned above which modeled in ETABS software. It decreased by 13 to 49 % for 9 records and increased by 2 to 17 % for 2 records. The use of bracing along with rotational friction damper modeled in ABAQUS software under the effect of each record has caused a decrease in base shear. The extent of these reductions was different for each record mentioned above. In each record modeled in ETABS software, the base shear of the structure has not reduced similarly; however, in some cases, the base shear has increased. It had a decrease of 11 to 37% for 7 records and an increase of 3 to 26% for 4 records.
Then a Single-storey frame with single-span With the same materials and specifications introduced in ETABS software in ABAQUS software Has been modeled. For lateral loading of columns, the lateral loading protocol based on ATC-24 and the instructions for using dampers in the design and reinforcement of buildings have been used.

According to Regulation No. 766 of the Program and Budget Organization, the loading cycles introduced in ETABS software with a frequency of 1.15T have been used in the ABAQUS Limited Components Software to move. The use of rotary braces and crankshafts in the ABAQUS limited component software under the influence of each of the discussed records has reduced the displacement of the structure relative to the structure without braces and without rotational friction dampers of the structure mentioned above was exerted under the record effect of the same earthquake in ABAQUS software The use of bracing along with rotational friction damper modeled in ABAQUS software under the effect of each record has caused a decrease in base shear. The amount of energy reduction for records understudy was not equal and varied from 8% to 34.7%. The hysteresis curves of base shear of braced structures with and without dampers are well presented.

کلیدواژه‌ها English

Composite steel bending frames
Energy damping
Circular damping
Hysteresis curve
Stiffness
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مهندسی عمران مدرس
دوره 21، شماره 4
مهر و آبان 1400
صفحه 185-203