Abstract




 
   

IJE TRANSACTIONS C: Aspects Vol. 31, No. 3 (March 2018) 394-404    Article in Press

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  SEISMIC RETROFITTING RC STRUCTURES WITH PRECAST PRESTRESSED CONCRETE BRACES- ABAQUS FEA MODELING
 
F. Nateghi A. and M. Vatandoost
 
( Received: August 07, 2017 – Accepted in Revised Form: October 12, 2017 )
 
 

Abstract    Precast prestreesed concrete braces are a new method for seismic strength of Concrete Structures which has the following benefits: a) no wet concrete work in construction site b) No bolt or anchorage to the existing frame c) easy to apply d) short construction period e) low construction cost, to evaluate seismic performance of strengthened structure a model consist of existing frame and concrete braces were created using ABAQUS (nonlinear-finite element) software.Comparison existing and strengthened frame showed that braces are effective in lateral drift decreasing.Study concrete compressive strength on seismic behavior of brace showed that when compression strength of brace is lower than existing frame, retrofitting system has low stiffness and wasn’t effective in reducing lateral drift, but in specimen with compressive strength ratio (brace to frame) two times or more, braces showed high strength and stiffness.

 

Keywords    Key words: Seismic Retrofitting, Seismic Strength, Concrete Braces, Precast Concrete, Prestressed Concrete, Reinforced Concrete Structure

 

چکیده    یک روش پیشنهادی جدید برای مقاوم سازی لرزه ای سازه های بتن آرمه به کار بردن مهاربندهای پیش تنیده پیش ساخته بتنی است که مزایای آن این است که در محل نصب با بتن تر کار نمی شود ، نصب آن آسان است و نیازی به انکر و بولت میلگرد به قاب موجود نمی باشد ، به همین دلیل سرعت اجرایی بالایی دارد که این خود موجب کاهش هزینه ها می شود.برای بررسی رفتار لرزه ای سازه مقاوم شده با مهاربند بتنی ، مدلی از قاب و مهاربند با نرم افزار المان محدود آباکوس ( ABAQUS FEA) ساخته شد ، مقایسه قاب اولیه و قاب تقویت شده موثر بودن مهاربندها را در کاهش تغییر مکان ها نشان داد. بررسی پارامتر رده مقاومتی بتن بر رفتار مهاربند نشان داد در نمونه انتخاب شده زمانی که رده مقاومتی مهاربند کمتر از رده مقاومتی قاب موجود باشد مهاربندها سختی کمی دارند و تاثیر چندانی در کاهش جابه جایی ها ندارند ولی در نمونه های با نسبت رده مقاومتی بیش از 2 برابر ، مهاربند سختی زیادی به سازه اعمال می نماید و کاهش تغییر مکان های جانبی آن مشهود است.

References    References  [1] WATANABE.F ,MIYAZAKI.S ,TANI.M , KONO.S, ”Seismic Strengthen Using Precast Prestressed Concrete Braces” 13th World conference on Earthquake Engineering, VANCOVER, B.C., Canada, August 1-6,2004,paper No.3406 [2] WATAABE.F, KONO.S” Retrofitting RC structures with precast prestressed concrete braces” proceeding of the 8th U.S National Conference on Earthquake Engineering, April 18-22,2006,san Francisco, California, USA, paper No.635 [3]   Desai JP, Jain AK, Arya AS, "Seismic response of R.C. braced frames", Computers and Structures, No. 4, 29(1988)557-68. [4] ISKHAKOV I, "Self Variable Stiffness System for Optimal Seismic Response of RC Frame with Concrete Braces", Earthquake Resistant Engineering Structures III, 2001. [5] KHALOO.A.R, MOHSENI.M.M,” Nonlinear Seismic Behavior of RC frames with RC Braces”, Asian Journal of civil Engineering (Building and housing) VOL.9,NO.6(2008),Pages 577-592 [6] ABAQUS- FEA takes advantage of the latest high-performance parallel computing ... For the full list of new features and enhancements in ABAQUS6.9,www.simulia.com/products/abaqus_fea.html [7] ABAQUS – Technical note – software help and documentation www.simulia.com/support/documentation.html [8] Xu S, NIU D,” Seismic behavior of reinforced concrete braced frame”, ACI structural Journal,No.1,100(2003) 120-125 [9] Watanabe F, Development of the “self-Installing PCa Brace Method for Seismic Reinforcement of Building Walls, October 2002. [10] ACI Committee 318,Building Code Requirements for Reinforced Concrete (ACI 318-05) and Commentary, American Concrete Institute,2005.‍‍ [11] Rodriguez M, Park R. “Repair and strengthening of reinforced concrete buildings for seismic resistance” Earth Spectra 1991;7(3):439–59. [12] OHISHI H, Takahashi M, Yamazaki Y. “A seismic strengthening design and practice of an existing reinforced concrete school building in Shizuoka City”. In: Proceedings of the ninth world conference on earthquake engineering. vol. VII. 1988. p. 415–20. 13. YAZGAN.A.U , NISHIYAMA.M, “Seismic performance Evaluation of Existing RC structures According to the Japanese standard and retrofitting with Prestressed Precast CFT and FRC braces”, Proceeding of the Fourteen world confrence on Earthquack Engineering, BeIJING,China,2008


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