بررسی پاسخ‌های ارتعاشی دال‌های بتنی دارای بازشو تحت تأثیر مولفه قائم زلزله

نوع مقاله : مقاله پژوهشی

نویسندگان

1 کارشناسی ارشد مهندسی سازه، گروه مهندسی عمران، واحد ارومیه، دانشگاه آزاداسلامی، ارومیه، ایران

2 استادیار، گروه مهندسی عمران، واحد ارومیه، دانشگاه آزاد اسلامی، ارومیه، ایران

چکیده

ساختمان‌ها در اثر زمین‌لرزه تحت اثر تحریک مولفه‌های لرزه‌ای قرار می‌گیرند که در سه راستای متعامد بر سازه وارد می‌شوند. در بیشتر موردها، در برآورد نیروهای زلزله به‌طور معمول از زلزله‌های راستای قائم صرف نظر و یا اثر آن‌ها ناچیز در نظر گرفته می‌شود. در حالی که مولفه‌ی قائم زلزله می‌تواند باعث ایجاد تغییرمکان‌ها و تنش‌های شدیدی بر المان‌های سازه‌ای، به‌ویژه دال‌های بتنی دارای بازشو، شود. در این پژوهش به بررسی اثر مولفه‌ی قائم زلزله بر دال‌های بتنی دارای بازشو پرداخته شده است. برای این منظور ساختمان‌های بتنی 5، 8 و 12 طبقه دارای دال‌های بتنی با 0 ،15 ،30 و 45 درصد بازشو تحت اثر سه رکورد زلزله حوزه نزدیک بم، نورثریچ و السنترو قرار گرفتند و به کمک تحلیل تاریخچه زمانی غیرخطی مقایسه‌ای بین تغییرمکان‌ها و تنش‌های ایجاد شده در آن‌ها انجام شد. نتیجه‌ی بررسی‌ها نشان دادند که سهم زلزله‌ی راستای قائم در تغییرمکان دال‌ها نسبت به تغییرمکان دال‌ها در اثر ترکیب سه راستا مقدار قابل توجهی نمی‌باشد. از طرف دیگر، مقایسه‌ی تنش‌ها در دال‌های بتنی نشان داد که تنش‌های ایجادشده با تغییرشکل‌های به‌وجود آمده در دال‌ها رابطه‌ی مستقیم دارد، به‌طوری که در مدل‌هایی که تغییر‌مکان بیشتری مشاهده شده است، تنش‌های برشی ایجادشده نیز مقدارهای بالاتری نشان می‌دهند. در همه‌ی سازه‌ها، هم در زلزله ترکیبی و هم راستای قائم، با افزایش درصد بازشو، تنش ایجادشده در دال‌ها نیز افزایش می‌یابد. در حالت کلی، بیشینه تنش ایجاد‌شده در دال‌ها در اثر رکورد‌های راستای قائم در برخی از موردها به اندازه‌ی 60 درصد بیشینه تنش‌های ایجادشده در اثر زلزله‌های ترکیبی می‌باشد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Investigating the Effect of Vertical Component of Earthquake on Seismic Responses of Concrete Slabs with Opening

نویسندگان [English]

  • Majid Khosrow Beigi 1
  • Ashkan KhodaBandehLou 2
1 M.Sc., Structural Engineering, Faculty of Engineering, Civil Engineering Department, Urmia Branch, Islamic Azad University, Urmia, Iran
2 Assistant Professor, Civil Engineering Department, Faculty of Engineering, Urmia Branch, Islamic Azad University, Urmia, Iran
چکیده [English]

One of the most important factors in the design of the structures is providing seismic resistance against earthquakes-induced forces. Buildings might be subjected to stimulations of earthquake seismic components, which affect the structure in three perpendicular directions. In estimations of the earthquake forces, the vertical component is usually neglected or understated. However, the earthquake vertical component can lead to drastic stress changes in the structural elements, especially the concrete slabs with opening. In this study, the effect of earthquake vertical component on concrete slabs with opening has been investigated. Three concrete structures with 5, 8, and 12 stories and slab openings of 0, 15, 30, and 45 percent were subjected to the effect of the near-field record of Bam, Northridge, and El Centro earthquakes. Non-linear time history analysis was used to comparatively study the structural displacements and stresses. The results indicated that the contribution of vertical earthquake component in slabs displacements was not significant compared to that of three direction combination. On the other hand, it was inferred that the acquired stresses have a direct relationship with deformations generated in the slabs, so that in models with larger displacements, higher stress levels were detected. For both the three direction combination and the vertical direction earthquakes, increasing the opening percentage would result in growing more stress in concrete slabs. Generally, the maximum produced stress in the slabs was in some cases about sixty percent of the maximum stresses induced by three directional combined earthquakes.

کلیدواژه‌ها [English]

  • Earthquake vertical component
  • Concrete Slab
  • opening
  • Non-linear time history analysis
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