بررسی اثر نامنظمی‌های قطع سیستم باربر جانبی و طبقه‌ خیلی نرم ‌بر عملکرد لرزه ای قاب‌های مهاربندی همگرا

نوع مقاله : علمی - پژوهشی

نویسندگان

1 استادیار دانشکده مهندسی عمران دانشگاه ایوانکی، سمنان، ایران

2 استادیار دانشکده عمران دانشگاه ایوانکی، سمنان، ایران

3 کارشناسی ارشد مهندسی سازه، دانشکده مهندسی عمران، دانشگاه ایوانکی، سمنان، ایران

4 گروه عمران، واحد مشهد، دانشگاه آزاد اسلامی، مشهد، ایران

چکیده

یکی از مسائل مهم در ساختمان‌ها، نامنظمی در پلان یا ارتفاع سازه می‌باشد که باعث افزایش خرابی‌های لرزه‌ای می‌گردد. در نامنظمی در ارتفاع، تغییرات ناگهانی در ویژگی‌های دینامیکی سازه شامل جرم، سختی و مقاومت جانبی رخ می‌دهد. در نتیجه، مرحله‌ی اتخاذ تصمیم در مورد پیکربندی ساختمان از اهمیت اساسی برخوردار است. ساختمان‌های نامنظم بایستی قادر به مقاومت در برابر نیروهای جانبی ناشی از زلزله و باد باشند. یکی از رایج ترین سیستم‌‌های مقاوم در برابر زلزله‌ در ساز‌های فولادی، سیستم مهاربندی می‌باشد که به دلیل عملکرد مناسب در زلزله‌های گذشته و کاهش جابجایی نسبی ساختمان‌ها مورد توجه مهندسین قرارگرفته است. اما ممکن است برخی محدودیت‌های معماری باعث جابجایی مهاربندها در تراز طبقات شود که مشمول نامنظمی قطع سیستم باربرجانبی گردد و یا این که در اثر‌ ضعف نظارت در برخی طبقات، مهاربند جانبی ضعیف یا حذف شده باشد‌ که در این صورت امکان ایجاد نامنظمی طبقه‌ی خیلی نرم در ساختمان وجود دارد.‌ در این تحقیق، قاب‌های‌ 5 طبقه با در نظر گرفتن 7 سناریو در سه حالت منظم، نامنظم طبقه‌ی خیلی نرم و نامنظم قطع سیستم باربر جانبی‌ در نظر گرفته شده است. این قاب‌ها بر اساس ضوابط لرزه‌ای استاندارد 2800 طراحی شده‌اند و سپس عملکرد آن‌ها با استفاده از روش‌های تحلیل استاتیکی معادل، دینامیکی طیفی‌ و دینامیکی تاریخچه زمانی تحت زلزله‌های نزدیک به گسل توسط نرم افزار‌ SAP‌2000 ارزیابی شده‌‌است. هدف از این تحقیق، بررسی دقت روش‌های تحلیل استاتیکی معادل، دینامیکی طیفی و دینامیکی تاریخچه زمانی می‌باشد. نتایج نشان داد که روش تحلیل دینامیکی تاریخچه زمانی نسبت به سایر روش‌های مورد مطالعه دقت بیش‌تری دارد. به عنوان نمونه، درصد خطای پاسخ تغییر مکان حداکثر قاب دارای نامنظمی قطع سیستم باربر جانبی در تحلیل استاتیکی معادل نسبت به تحلیل‌های طیفی و تاریخچه زمانی به ترتیب 15 و 77 درصد می‌باشد.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Investigation the Effect of Cutting the Lateral Bearing System and Very Soft Story Irregularities on the Seismic Performance of Concentric Braced Frames

نویسندگان [English]

  • vahid saberi 1
  • hamid saberi 2
  • Mojtaba Babanegar 3
  • Abbasali Sadeghi 4
  • Ali Moafi 3
1 Assistant Professor, Department of Civil Engineering, University of Eyvanekey, Semnan, Iran
2 Assistant Professor, Department of Civil Engineering, University of Eyvanekey, Semnan, Iran
3 M.Sc.in Structural Engineering, Faculty of Civil Engineering, Eyvanekey University,Semnan, Iran
4 Department of Civil Engineering, Mashhad Branch, Islamic Azad University, Mashhad, Iran
چکیده [English]

One of the most important issues in buildings is irregularity in the plan or height of the structure, which causes increasing the seismic damages. In irregularity in height, sudden changes in the dynamic properties of the structure including mass, lateral stiffness and strength of the structure occur. Therefore, the stage of making decision for determining the building configuration has a fundamental importance Irregular buildings must be able to withstand the lateral forces of earthquakes and winds. One of the most common earthquake-resistant systems in steel structures is the bracing system, which has been considered by engineers due to its good performance in previous earthquakes and reduced drift of buildings. However, some architectural constraints may cause the braces to be moved to the story level, which is subjected to irregularity of cutting the lateral bearing system, or the lateral braces may be weakened or removed due to poor supervision in some stories, in which case the story may be irregular. There is very soft story in the building. In this study, 7 scenarios in three states such as regular, very soft irregularity, and irregularity of cutting the lateral bearing system is considered for 5-story frame. These frames are designed based on seismic guidelines of standard 2800, and then, the performance of them has been evaluated by SAP‌2000 software using analyses methods such as equivalent static, spectral dynamics and time history dynamics under near-fault earthquakes. The aim of this study is to investigate the accuracy of these methods. The results showed that time history dynamic analysis is more accurate than other methods. For example, the error rate of the maximum displacement response of frame with irregularity of cutting the lateral bearing system in equivalent static analysis compared to spectral and time history dynamic analyses are 15% and 77%, respectively.

کلیدواژه‌ها [English]

  • Height Irregularity
  • Cutting the Lateral Bearing System
  • very soft story
  • Equivalent Static Analysis
  • Spectral Dynamic Analysis
  • Time History Dynamic Analysis
  • Near-Fault Earthquake

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سابقه مقاله

  • تاریخ دریافت: 25 مرداد 1399
  • تاریخ بازنگری: 05 آبان 1399
  • تاریخ پذیرش: 30 دی 1399

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