بررسي قابليت اعتمادپذيري احتمالاتي اتصالات پاي ستون‌ها در سازه‌هاي فولادي

Investigation of probabilistic reliability analysis of the column base connections in steel structures

مسايل مربوط به سازه، عدم قطعيت‌هاي فراواني دارند. بعضي از اين ابهامات قابل شناسايي و برخي ديگر به علت ناشناخته‌بودن در نظر گرفته نمي‌شوند. يكي از عدم قطعيت‌ها، اتصالات پاي ستون‌ در سازه‌هاست. در سازه‌ها اتصال پاي ستون با فرض‌ ايده‌آل كاملاً مفصلي و يا كاملاً گيردار تحليل و طراحي مي‌شوند، در نتيجه‌ انتظار مي‌رود نتايج به‌دست‌آمده در طراحي اعضا ستون‌ها و تيرها محافظه‌كارانه باشد. در اين مطالعه با توجه به حساسيت ذكرشده، تاثير سختي دوراني و مقاومت اتصال پاي ستون با توجه به عدم قطعيت‌هاي موجود مورد ارزيابي قرار گرفته است. با توجه به تحليل‌هاي صورت‌گرفته اين نتيجه حاصل شد كه رفتار و تغيير پارامترهاي توصيف‌كننده‌ي اتصال پاي ستون بسيار وابسته به سختي دوراني و لنگر تسليم اتصال است. در اين مطالعه همچنين با استفاده از عدم قطعيت‌هاي در نظر گرفته‌شده و روابط احتمالاتي ميانگين سختي دوراني و دوران اتصال پاي ستون با درصد اطمينان مشخص برآورد شده است.

Reliability is the probability that a system will perform its function over a specified period of time and under specified service conditions. Reliability theory was originally developed by maritime and life insurance companies in the 19th century to compute profitable rates to charge customers. An engineering structure’s response depends on many uncertain factors such as loads, boundary conditions, stiffness, and mass properties. Each of these requirements is termed as a limit-state or constraint. The study of structural reliability is concerned with the calculation and prediction of the probability of limit-state violations at any stage during a structure’s life. The probability of the occurrence of an event such as a limit-state violation is a numerical measure of the chance of its occurring. Once the probability is determined, the next goal is to choose design alternatives that improve structural reliability and minimize the risk of failure. Some of these uncertainties can be identified and others because of unknowing problems are not considered. One of these uncertainties in structures is column base connections. engineers in designing of a structure assume that column base connections been totally pinned or fixed and by using this assumptions the structures are designed, in result of this assumptions columns or beams in structures designed conservative. In present study by considering the sensitivity of mentioned in above, the effect of rotational stiffness and the strength capacity of a base connection evaluated by considering uncertainties in this connection. Results showed that change in parameters of column base connections depends on rotational stiffness and yield moment, also by considering uncertainties and Probabilistic Relations average of rotational stiffness and rotation with specific confidence estimated.