بهسازی اتصالات ضعیف پایه های قابی شکل پل های بتنی با استفاده از کامپوزیت سیمانی الیافی و نبشی‌های فولادی

نوع مقاله: مقاله پژوهشی

نویسندگان

1 کارشناس ارشد، دانشکده مهندسی عمران، دانشگاه سمنان

2 دانشیار، دانشکده مهندسی عمران، دانشگاه سمنان

چکیده

اتصالات تیر به ستون از نقاط حساس و آسیب پذیر در پایه های قاب­های خمشی پل ها هستند و آسیب دیدگی این ناحیه در برابر بارهای جانبی زلزله منجر به کاهش عملکرد لرزه­ای قاب و افزایش جابه­جایی قاب و در نهایت تخریب اعضاء و حتی تخریب کل سازهپل  می شود. با توجه به اهمیت چشمه اتصال در این قاب­ها، اجرای صحیح و مطابق جزئیات آیین نامه­ها تاثیر بسزایی در عملکرد لرزه­ای قاب دارد. در این مقاله، تاثیر خاموت ناحیه چشمه اتصال در یک اتصال بتن آرمه پایه پل ها با مقیاس یک دوم، به صورت آزمایشگاهی و عددی، تحت بار لرزه­ای رفت و برگشتی مورد بررسی قرار گرفته و سپس یک اتصال ضعیف دیگر فاقد خاموت در چشمه اتصال،  با استفاده از مصالح کامپوزیت سیمانی الیافی توانمند(HPFRCC)، مقاوم­سازی شده و تاثیر آن در عملکرد اتصال و میزان جبران فقدان خاموت چشمه اتصال بررسی شده است. همچنین به منظور بررسی حالات مختلف تقویت اتصال پایه های پل، هفت نمونه تحلیلی مختلف معرفی شده و تاثیر پانل­های مختلف HPFRCC در بهسازی اتصال و تقویت اتصال بتنی ضعیف توسط نبشی­های پیش­تنیده فولادی مورد مطالعه و مقایسه قرار گرفته است. در این تحقیق، منحنی های هیسترزیس بار- تغییرمکان و پوش آن­ها و منحنی های استهلاک انرژی و سختی و  افت سختی اتصالات مورد بررسی قرار گرفته است.  نتایج حاکی از افزایش ظرفیت خمشی و شکل­پذیری و کاهش سریع افت سختی اتصال در سیکل­های اولیه در اتصال دارای HPFRCC در محل اتصال، نسبت به اتصال فاقد خاموت در چشمه اتصال  قاب های بتنی پل­ها بوده است. استفاده از پانل­های کامپوزیتی سیمانی با الیاف توانمند، ماکزیمم ظرفیت باربری اتصال پایه پل بتنی را نسبت به اتصال ضعیف از 17 تا 48 درصد، افزایش داد.

کلیدواژه‌ها


عنوان مقاله [English]

Retrofitting of Deficient Connections in Frame-Shape Piles of RC Bridges using Fiber Cementitious Composites and Steel Angles

نویسندگان [English]

  • Neamat Heydarian 1
  • M. Kazem Sharbatdar 2
  • Azadeh Haghighat 1
1 M.Sc. of Structural Engineering, Faculty of Civil Engineering, Semnan University, Semnan, I. R. Iran.
2 Associate Professor, Faculty of Civil Engineering, Semnan University, Semnan, I. R. Iran.
چکیده [English]

Beam-column connections are vulnerable areas of reinforced concrete moment frames-shapes of bridge piles and damaging of this area under the earthquake loads results in decreasing of seismic performance of frame and increasing of frame drift and eventually destruction of members and even the entire bridge structure. Due to the importance of connection zones in these frames, correct implementation based on regulations has significant impact on seismic performance of the frame. In this paper, the influence of stirrup of panel zone in a concrete connection of bridge piles with a scale of one-half has been conducted experimentally and numerically under cyclic seismic loading and then another deficient connection without any stirrup in the panel zone has been reinforced by high-performance fiber-reinforced cementitious composites (HPFRCC), and its effect on connection performance and compensation of the lack of stirrup of the panel zone has been studied. Also, to evaluate different states of connection strengthening of bridge piles, seven different analytical samples have been presented and the influence of different panels of HPFRCC on connection improvement and in strengthening the weak concrete connection by prestressed steel angels has been studied and compared. In this study, the hysteresis curves of load-displacement and their envelope curves and also energy dissipation, stiffness and stiffness loss curves of the connections have been studied. Results indicated that increasing the flexural capacity and ductility and rapid decreasing in stiffness-loss of connection in primary cycles of connection retrofitted with HPFRCC were more than those of the connection without stirrup in connection zone of bridge frame-shape piles. Maximum capacity of deficient connection of RC bridge piles was increased by 17-48% using high performance fiber reinforced cementitious composite (HPFRCC) panels.

کلیدواژه‌ها [English]

  • Reinforced concrete moment connection
  • HPFRCC
  • ductility
  • Prestressed angel
  • Bridge piles
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