مدل‌سازي اجزاي محدود ديوارهاي آجري كلافدار ساخته‌شده بر اساس آيين‌نامه‌ي زلزله‌ي ايران

Finite Element Modeling Confined Masonry Walls Constructed based on Iranian Seismic Code

جهت ارتقاي ضوابط آيين‌نامه‌يي در مورد ساختمان‌هاي آجري كلافدار، مطالعات بيشتر تحليلي و آزمايشگاهي بر روي اين سازه ها لازم به نظر مي رسد. در مورد مدل‌سازي اجزاي محدود ساختمان‌هاي آجري كلافدار، مطالعات محدودي در ادبيات فني موجود است. در اين نوشتار، پارامترهاي مناسب براي مدل‌سازي اجزاي محدود دو ديوار آجري كلافدار، با و بدون بازشو، ارايه مي شود. اين پارامترها را نگارندگان از نتايج آزمايش‌هاي انجام‌شده استخراج و ارايه كرده‌اند. نتايج تحليل نيز با نتايج آزمايش‌هاي انجام‌شده مقايسه و صحت‌سنجي شده است. نتايج نشان مي‌دهد كه مدل اجزاي محدود ارايه‌شده، در عين سادگي تخمين خوبي از رفتار ديوار آجري كلافدار ارايه مي كند؛ و همچنين پارامترهاي مدل‌سازي براي ديوارهاي ساخته‌شده بر طبق استاندارد 2800 و با مصالح مرسوم در ايران، اختلاف قابل توجهي با پيش‌فرض‌هاي معمول در ساير نقاط دنيا دارند.

Confined masonry walls are made up of masonry walls and confining elements on their four sides. This system is a conventional form of housing construction, as well as a good alternative for post-disaster reconstruction of seismically damaged and/or collapsed buildings in many countries, including Iran. Seismic behavior of confined masonry buildings rigorously depends on material properties, construction methods and worker skill levels. There are few studies that consider the effects of the local constructing parameters of Iran, such as common materials and labour skills, on the modeling of confined masonry walls. In this paper, a computer program, DIANA, is used for the finite element modeling of confined masonry walls. Modeling parameters are estimated by material tests conducted in the structural laboratory of the International Institute of Earthquake Engineering and Seismology (IIEES). The models are validated with the results of tests performed on two one-story one-bay confined masonry walls performed in the same laboratory. The walls are designed according to the Iranian seismic code and are subject to lateral cyclic loading; the first being solid and the second with a central window opening. The scale of 1:2 is assigned to all parts of the walls including bricks. Two types of mortar with different sand to cement ratio are used to make the masonry walls. Proper modeling parameters for concrete ties and the macro modeling of masonry panels, which are estimated by material tests, are introduced for both specimens. The results obtained from the models match the experimental results quite well. Results show that the elasticity module of such walls are considerably smaller than that proposed in previous studies in foreign counties. Also, results indicate that changing the sand to cement ratio of mortar can affect the lateral resistance of walls significantly. So, it can be concluded that this ratio should be addressed in the Iranian codes.