ارزیابی قابلیت اعتماد قاب‌های خمشی سه‌بعدی طراحی شده بر مبنای آیین‌نامه‌های نسخه 87 و 92 فولاد ایران

نوع مقاله : علمی - پژوهشی

نویسندگان

1 دانشجوی دکتری سازه، دانشکده عمران، دانشگاه صنعتی شاهرود، شاهرود، ایران

2 دانشیار، دانشکده عمران، دانشگاه صنعتی شاهرود، شاهرود، ایران

3 استادیار، دانشکده فنی و مهندسی، دانشگاه آزاد اسلامی واحد شاهرود، شاهرود، ایران

10.22065/jsce.2020.185303.1858

چکیده

آگاهی از احتمال خرابی و شاخص ایمنی سازه ی طراحی و اجرا شده بر مبنای آیین‌نامه‌ها می تواند نگرش مهندسین طراح را نسبت به مقوله ی خرابی یا ایمنی سازه ارتقا دهد. در این مقاله به بررسی احتمال خرابی و شاخص ایمنی قاب های خمشی فـولادی سه‌بعدی پرداخته شده است. یک قاب خمشی فولادی سه طبقه و یک قاب خمشی فولادی شش طبقه که بر مبنای آیین‌نامه‌های قدیم ایران بارگذاری و طراحی شده اند، انتخاب شده است. جهت تحلیل المان محدود قاب خمشی سه‌بعدی و تحلیل قابلیت اعتماد سیستم با استفاده از روش مونت‌کارلو، برنامه ای به زبان برنامه‌نویسی CSHARP نوشته‌شده است. در تحلیل قابلیت اعتماد، عدم قطعیت‌ها در مقاومت تسلیم و ضریب الاستیسیته فولاد، بارهای ثقلی و نیروهای جانبی، سطح مقطع عرضی و مدول مقطع پلاستیک اعضای قاب در نظر گرفته‌شده است. محاسبه ی احتمال خرابی و شاخص ایمنی سیستم قاب خمشی در دو حالت بر اساس آیین‌نامه‌های قدیم نسخه 1387 و جدید نسخه 1392 فولاد ایران انجام‌شده و مورد مقایسه قرارگرفته است. ملاحظه شده است که ساختمان‌های طراحی‌شده برمبنای آیین‌نامه‌های قدیم چنانچه تحت شرایط آیین‌نامه‌های جدید ایران ارزیابی شوند، کاهش در تراز ایمنی را از خود نشان می دهند. همچنین تأثیر همبستگی آماری بین بارهای ثقلی و نیروهای جانبی در تعیین شاخص ایمنی قاب بررسی شده است. آنالیز حساسیت انجام‌شده برای ضریب پراکندگی مقاومت تسلیم فولاد نشان می‌دهد که تغییرات آن بعد از مقدار 07/0، می‌تواند تأثیر قابل توجهی در قابلیت اعتماد قاب خمشی فولادی داشته باشد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Reliability Assessment of Three-dimensional Moment Resisting Frames Designed According to the Iranian National Building Code, Part 10: Steel Structures, 2008 and 2013 Editions

نویسندگان [English]

  • Hamidreza Irani 1
  • Vahid Reza Kalatjari 2
  • Mohammadhosein Dibaei Bonab 3
1 Ph.D. Student, Civil Engineering Department, Shahrood University of Technology, Shahrood, Iran
2 Associate Professor, Civil Engineering Department, Shahrood University of Technology, Shahrood, Iran
3 Assistant Professor, Faculty of Engineering, Islamic Azad University Shahrood Branch, Shahrood, Iran
چکیده [English]

Awareness of the probability of failure and the safety index of a structure designed and implemented on the basis of regulations and codes can enhance the designer's attitude towards the failure or safety of the structure. This paper examines the probability of failure and safety index of 3D steel moment frames. A three-story steel moment frame and a six-story steel moment frame loaded and designed on the basis of the previous drafts of National Building Regulations of Iran have been selected. In order to perform the finite element analysis of the 3D moment frame and system reliability analysis, a program with CSHARP programming language is written incorporating the Monte Carlo method. In reliability analysis, the uncertainties in the yield strength and the Young's modulus of steel, gravity loads and lateral forces, cross-sectional and plastic section modulus of the frame members were considered. The calculation of the probability of failure and the safety index of the framing system in two cases, according to the old, 2008 edition and new, 2013 edition of Iranian National Building code, Part 10: Steel Structures, have been done and compared. It was noted that assessment of buildings constructed on the basis of the old regulations with new drafts of National Building Regulations of Iran resulted in decreased safety levels. Also, the effect of statistical correlation between gravity loads and lateral forces in determining the frame safety index has been investigated. The sensitivity analysis performed for the steel coefficient of variation showed that its variation after the value of 0.07 can have a significant effect on the reliability of the steel moment frame.

کلیدواژه‌ها [English]

  • Reliability
  • 3D Steel Moment Frames
  • System Safety Index
  • Monte Carlo Method
  • Sensitive Analysis
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