بررسي عددي عملكرد داخل صفحه ديوارهاي بنايي تقويت شده با مصالح مركب پايه سيماني مهندسي با تاكيد بر تاثير اتصال به شالوده

وسعت احداث سازه‌هاي بنايي و ضعف آنها در برابر زلزله، ضرورت تحقيق راجع به روش‌هاي نوين بهسازي لرزه‌اي اين سازه‌ها را دو چندان مي‌نمايد. اخيرا در كنار روش‌هاي متداولي چون مش و شاتكريت و الياف پليمري، مصالح مركب پايه سيماني مهندسي ECC جهت تقويت ديوارهاي بنايي مورد توجه محققين قرار گرفته‌است. وجه تمايز اين نوع مصالح نوين، شكل‌پذيري بالا در كشش مي‌باشد. در تحقيق حاضر تاثير اين مصالح روي عملكرد ديوارهاي باربر بنايي با مودهاي شكست داخل صفحه بصورت عددي بررسي شده‌است. نتايج تحقيق مبتني بر روش عددي مي‌باشد كه جهت صحت‌سنجي مدل از اطلاعات موجود آزمايشگاهي استفاده شده‌است. روش تقويت به صورت يك و دو طرفه درنظر گرفته شده‌است. همچنين لايه تقويت به دو صورت متصل و جداي از شالوده زير ديوار باربر مدل شده‌است. تغيير مود شكست ديوار تقويت شده از حالت ترد به شكل پذير همراه با رفتار سخت‌شوندگي در ناحيه غيرخطي از نتايج مشترك مدل‌ها مي‌باشد. افزايش مقاومت و جذب انرژي از ديگر نتايج تحقيق مي‌باشد كه مقدار آن بسته به چگونگي اتصال لايه تقويت به شالوده متغيير است. در شرايطي كه بين لايه تقويت و شالوده اتصال برقرار گردد مقاومت براي حالت تقويت يك و دو طرفه به ترتيب 3.5 و 6 برابر ديوار تقويت نشده مي‌باشد. اين مقدار در جذب انرژي به ترتيب 3 و 6.5 بدست آمده‌است. همچنين تاثير اتصال لايه تقويت با شالوده در بهبود رفتار ديوارهاي با مود شكست لغزش درز ملات به مقدار محسوسي از ديوارهاي با مود شكست قطري بيشتر مي‌باشد.

The extent of masonry structures and their weaknesses against earthquakes will increase the need for research on new ways of seismic rehabilitation of these structures. Recently, in addition to conventional techniques such as Mesh, Shotcrete, and FRP, new materials such as ECC materials have been considered by the researchers to retrofit the masonry walls. The composite materials of cement base, which is one of the types of cement base materials, due to the presence of fibers in the matrix, has a significantly different tensile strain capacity than that of conventional concrete, so that the range of this parameter for a typical mortar is 0.015%, and for composite materials of ECC is from 0.5 up to 6%. In the present study, the effect of these materials on the performance of the bearing masonry walls with in-plane failure modes including the diagonal tension mode (brittle mode) and the bed-joint sliding mode (the ductile mode) were investigated. The results of the research are based on the numerical method. ABAQUS software was used for numerical modeling. Due to validate the model, the available laboratory information of as-built masonry walls has been used. The as-built masonry walls are half scale. The wall dimensions for diagonal tension mode and bed-joint sliding mode were 1900x1400x110 and 2700x1400x160 mm, respectively. The gravity load of the wall was 0.1 MP. The walls strengthened with 20 mm ECC layers on one and both sides. In one case, ECC layers were joint to the foundation and in other case were not. A change in failure mode of strengthened walls (brittle to ductile) and hardening behavior were the main achievement of this research. If the connection between ECC layers and the foundation is absent, the failure mode of strengthened walls will be toe-crushing and rocking mode. If the connection between ECC layers and the foundation is present, the failure mode of strengthened walls will be toe-crushing and bed-joint sliding mode. Other obtained results showed an effective increase in strength and dissipated energy. The extent of this increase depends on how ECC layer is connected to the foundation. If there is no connection between ECC layers and the foundation, the strength and dissipated energy of walls with diagonal tension failure mode for one-side and both-sides ECC layers will be 2.3 and 3 times, respectively, in comparison with those of as-built masonry walls. Whereas for the bed-joint sliding mode, the extent of wall strength and dissipated energy is 1.4 and 1.8. according to the obtained results and comparing the properties of the wall strengthened by one-side and both- sides ECC layers, a significant difference was not observed, especially in bed-joint sliding mode. Appositively, if there is a connection between ECC layers and the foundation, the strength of walls for one-side and both-sides ECC layers will be 3.5 and 6 times, respectively, in comparison with those of as-built masonry walls. Whereas the dissipated energy of walls will be 3 and 4.5 times. Based on these results, if the ECC layers and the wall foundation are connected, the capacity of strengthened walls will be optimized