بررسی آزمایشگاهی زوال چرخه‌ای تیر بتن‌آرمه سبک تحت بارگذاری تناوبی

نوع مقاله : علمی - پژوهشی

نویسندگان

1 گروه سازه و زلزله، دانشکده مهندسی عمران، دانشگاه صنعتی نوشیروانی بابل

2 دانشیار، دانشگاه صنعتی نوشیروانی بابل

چکیده

المان‌ها و سیستم‌های سازه‌ای در طول عمر خود دچار کاهش مقاومت و سختی می‌گردند که اصطلاحاً زوال نامیده می‌شود. یکی از متداول‌ترین نوع زوال در سازه‌های بتن‌آرمه، زوال چرخه‌ای می‌باشد که به دلیل بار های رفت و برگشتی ناشی از زلزله ایجاد می‌شود؛ سازه‌هایی که در طول عمر خود، یک یا چند زلزله را تجربه می‌نمایند، دچار درجه‌ای از زوال می‌گردند که پاسخ لرزه‌ای آن‌ها را در برابر زلزله‌های بعدی تحت تأثیر قرار می‌دهد. مدل‌های رفتاری موجود، زوال چرخه‌ای حاصل از حرکت رفت و برگشتی در طول یک زلزله را در نظر می‌گیرند ولی بسیاری از این مدل‌ها اثرات زوال ناشی از زلزله‌های قبلی را در نظر نمی گیرند؛ درصورتی‌که این زوال می‌تواند اثرات قابل‌توجهی در رفتار المان‌های سازه‌ای داشته باشد. در این پژوهش، به بررسی زوال چرخه‌ای تیر بتن‌آرمه و تأثیر آن در رفتار بعد از زلزله آن‌ها به صورت آزمایشگاهی پرداخته می‌شود. برای این منظور، 12 تیر بتن‌آرمه با مشخصات یکسان ساخته شده و تحت بارگذاری جابجایی کنترل قرار می‌گیرند. برای ایجاد زوال ناشی از زلزله، از بارگذاری تناوبی با دامنه ثابت (هارمونیک) استفاده می‌شود. به‌منظور بررسی اثر زوال چرخه‌ای در رفتار بعد از زوال المان‌ها سه سطح زوال کم، متوسط و زیاد انتخاب می‌گردد. پس از انجام آزمایش، نتایج مربوط به نمودارهای هیسترزیس، زوال مقاومت و ظرفیت جذب انرژی برای نمونه‌ها ارائه و مورد بحث قرار می‌گیرند. نتایج آزمایشات نشان می‌دهد که با افزایش سطح زوال، میزان جذب انرژی تیرهای بتن‌آرمه کاهش می‌یابد؛ به خصوص در تیرهای با سطح زوال زیاد، میزان جذب انرژی تیرها بیش از 40 درصد کاهش می‌یابد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Experimental Investigation of Cyclic Degradation of Light RC Beams under Periodic Loading

نویسندگان [English]

  • Taghi Mofid 1
  • Hamidreza Tavakoli 2
1 Civil Engineering, Babol Noshirvani University of Technology, Babol, Iran
2 Associate Professor, Faculty of Civil Engineering, Babol Noshirvani University of Technology, Babol, Iran
چکیده [English]

Structural elements and systems experience a decrease in strength and stiffness throughout their lifetimes, called degradation. One of the most common types of degradation in RC (Reinforced Concrete) structures is the cyclic degradation caused by earthquakes. Structures that experience one or more earthquakes during their lifetime, experience a degree of degradation that affects their seismic response to subsequent earthquakes. Existing numerical models take into account the cyclic degradation of an earthquake, but many of these models neglect the effects of degradation caused by previous earthquakes; Recent studies show that this degradation has significant effects on the response of structural elements. In this study, the cyclic degradation of RC beams and their impact on the post-earthquake behavior of the beams is investigated experimentally. For this purpose, 12 RC beams are manufactured and subjected to displacement-control loading. Periodic loading with uniform amplitude is used to simulate the earthquake cyclic degradation. Three levels of slight, moderate and extensive degradation are selected to investigate the effect of cyclic degradation on the post-earthquake behavior of elements. After the experiment, the results of the hysteresis diagrams, strength degradation and energy absorption of the specimens are presented and discussed. The results of this study show that as the level of cyclic degradation increases, the energy absorption of RC beams decrease; Especially in the extensive level of degradation, the energy absorption of the beams is reduced by more than 40%.

کلیدواژه‌ها [English]

  • Cyclic degradation
  • RC Beams
  • Periodic loading
  • Hysteresis behavior
  • Post-earthquake behavior
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