برآورد ﭼندسطحي ضريب رفتار براي سازه‌هاي بتن‌آرمه با سيستم قالب‌تونلي

MULTI-LEVEL R-FACTOR DETERMINATION FOR RC TUNNEL-FORM BUILDINGS

به دليل فقدان اطلاعات كافي و تجربه‌ي آسيب‌پذيري بر ساختمان‌هاي بتن‌آرمه با شيوه‌ي ساخت قالب‌تونلي در زلزله‌هاي پيشين، استفاده از ضرايب رفتار سازه‌هاي با ديوار باربر بتن‌آرمه در يك فرآيند طراحي لرزه‌يي، نگراني‌هايي را به‌دنبال دارد. اين نقصان از چالش‌هاي اصلي طراحي سازه‌هاي مذكور به روش آيين‌نامه‌هاي طراحي لرزه‌يي است. در اين مطالعه، ضمن تعريف و تشريح مراحل استخراج دو پارامتر ضريب رفتار طلب و ضريب رفتار ظرفيت، پارامترهاي ذكرشده براي سازه‌هاي قالب‌‌تونلي 2، 5، و10 طبقه با پلان منظم، كه براساس آيين‌نامه‌هاي موجود طراحي شده‌اند، استخراج شده است. مهم‌ترين وجه تمايز مطالعه‌ي حاضر با ديگر مطالعات مشابه، بيان چندسطحي ضريب رفتار و استخراج آن با توجه به ميزان تقاضاي زلزله و ميزان آسيب قابل قبول به عنوان سطوح عملكردي مورد انتظار در طراحي سازه است. نتايج به‌دست‌آمده، بيان‌گر ظرفيت و مقاومت بالاي سيستم و عملكرد لرزه‌يي مناسب سازه‌هاي مورد مطالعه است. از طرفي، انتخاب ضريب رفتار 5، جهت طراحي اوليه، به‌خوبي متضمن سطح عملكرد قابليت استفاده‌ي بي‌وقفه براي هر 3 سازه‌ي تحت بيشينه‌ي سطح شدت زلزله‌ي طراحي آيين‌نامه‌ي ايران است.

Despite unique seismic resistance characteristics of reinforced concrete tunnel form buildings, a literature review surveyed rare research works found for this type of buildings. Unfortunately, no special seismic code is published for reinforced concrete wall-slab system with tunnel form, and there is only little information on the seismic behavior of this structural system type in technical and research docs. Therefore, based on reasonable numerical results, seismic behavior and performance of structures constructed with this technique, considering the effective factors in response, is highly noteworthy in a seismic code of development process. The behavior factors in the seismic design codes are based on engineering judgment and are provided based on observations of various performances of structural systems against past strong earthquake shakings. For reinforced concrete tunnel-form buildings, due to lack of enough information and observations of damages induced by past earthquakes, using the behavior factor of reinforced concrete bearing wall system in the current seismic design process appears as notable concerns which are the main challenges in designing these structures based on the equivalent lateral force method. This type of structural system has recently innovated and used in mass production houses, so there is rare information pertaining to its behavior under strong earthquakes. Since including the behavior factors in seismic codes are based on engineering judgment from observing its past seismic performance, developing these factors for this new system needs more research works. The most distinctive feature of this study with respect to similar studies is multi-level definition of behavior factors, their extraction with respect to seismic intensity, and the accepted damage level as expected performance levels in designing structure. Hence, the demand/capacity behavior factors are determined with a more accurate attitude involving the effective parameters such as ductility, over-strength, redundancy, seismic hazard level, performance levels, etc. The results showed high capacity and resistance of system and good seismic performance of structures under the current study. Thereby, choosing behavior factor of 5 for initial design ensures the immediate occupancy performance level for all three structures under high earthquake intensity considered in seismic design code of Iran.