روش پیشنهادی جدید برای ارزیابی ظرفیت باربری پایه پل‌های بتنی آسیب‌دیده پس از زلزله‌های حوزه نزدیک

نوع مقاله : پژوهشی اصیل (کامل)

نویسندگان
فرهاد دانشجو 1
مختار انصاری 2
1 استاد، دانشکده مهندسی عمران و محیط زیست ، دانشگاه تربیت مدرس
2 استادیار گروه مهندسی عمران، دانشکده مهندسی ، دانشگاه بزرگمهر قائنات
10.22034/25.1.59
چکیده
هنگامی که پل‌ها دچار تغییر شکلهای غیر­الاستیک در زلزله­های نزدیک گسل می‌شوند عمدتاً به راستای قائم اولیه برنمی‌گردند و دچار تغییر‌شکلهای پس‌ماند قابل توجهی می‌شوند. این تغییر شکل پس‌ماند زیاد باعث می‌شود که پل‌ها با وجود عدم فرو‌ریزش، غیر قابل تعمیر باشند و امکان استفاده از آنها پس از زلزله مقدور نباشد. جابه جایی های ماندگار قابل توجه در پل های آسیب دیده در زلزله های نزدیک گسل باعث می شود بهره برداری ازآنها پس از زلزله تحت اثر بارهای ثقلی به دلیل ممانهای قابل توجه ناشی از اثرات پی-دلتا به مخاطره بیفتد . بنابراین تخمین تقاضا و ظرفیت دینامیکی بر اساس جابه‌جایی پس‌ماند پل‌ها در زلزله‌های نزدیک‌‌گسل از موضوعات مهم ارزیابی سرویس‌پذیری پل‌ها پس از زلزله است. در این تحقیق بر‌خلاف آئین‌نامه‌ها و تحقیقات قبلی، در پیشنهاد یک مقدار مشخص برای جابه‌جایی ماندگار مجاز، روشی تحلیلی برای محاسبه ظرفیت باربری پایه پل­های آسیب­دیده براساس جابه جایی ماندگار با توجه به نسبت‌های مختلف ابعادی پایه و شدت زلزله­های وارده معرفی می­گردد. در این روش‌ تغییرات سختی و مقاومت پایه­های بتن مسلح، در سطوح مختلف زلزله، بر اساس میزان آسیب وارده در محاسبه ظرفیت دریفت ماندگار در نظر گرفته می‌شود.

کلیدواژه‌ها

موضوعات

عنوان مقاله English

A new approach to assessment of load carrying capacity of damage concrete bridge piers on near-fault earthquakes

نویسندگان English

Farhad Daneshjoo 1
mokhtar ansari 2
1 Professor of Civil Eng., Faculty of Civil and Environmental Engineering, Tarbiat Modares University, Tehran, Iran
2 Assistant Professor of Civil Eng., Faculty of Engineering, Bozorghmehr University of Qaenat, Qaen, Iran
چکیده English

Modern reinforced concrete bridge structures affected by a near-fault strong ground motion usually exhibit a large lateral residual deformation and end up standing in an ‘out of plump’ position. Even though these bridges have not collapsed, they are mostly not any more functional in the immediate aftermath of the ground shaking and generally deemed irreparable. These relatively large residual displacements observed in damaged bridges by near-fault strong ground motions jeopardize the operability of the bridge after the seismic event partly due to the introduction of the additional moments in the columns induced by the offset of vertical gravity loads. Therefore, it is of great significance to be able to accurately predict the demand and capacity of residual drifts for bridges exposed to near-field ground motions for decision-making about their serviceability upon a major seismic event. In this research, on the contrary to the design code requirements and the previous studies, an analytical model is proposed which can account for the bridge pier properties and the ground motion characteristics. The proposed model takes the variation in the stiffness and strength of the bridge pier which is proportional to the incurred damages in different earthquake shaking levels into account in order for the prediction of permanent drift capacity.

کلیدواژه‌ها English

Residual drift
Near-field earthquake
P-Delta effects
bridge serviceability
stiffness and strength variation
earthquake levels
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مهندسی عمران مدرس
دوره 25، شماره 1 - شماره پیاپی 81
فروردین و اردیبهشت 1404
صفحه 59-70