Mohammad Vaghefi

Since in bubble deck (BD) system, the concrete in the middle of deck’s cross sections, mainly in the middle of the spans, is removed, the slabs become lighter compared to the traditional slabs. The application of this type of structural system has been recently increased. In the researches, the ductility factor is expressed generally for the reinforced concrete (RC) structures, with momentresisting system (MRS), and dual systems. These include particularly, the MRSs, shear walls, and the flat slabs having mainly the BD system. In this research, the variations of the ductility of RC structures constructed with BD are assessed by applying the numerical modeling and nonlinear static analysis. Based on the evaluation of the obtained results, it can be concluded that the ductility of structures with dual systems, including MRS and shear wall (MRSSW), is more than the ductility of the structures with single MRSs. In the structures with MRSSW by increasing the ratio of the span length to story height (L/H) and also the number of stories, ductility factor will decrease and the rates of these decreases are considerable, while in MRS the number of stories and also the L/H ratio have less effect on the ductility factor. Among the structures with dual systems, including MRSSW, the low-rise structures with high ratios of span length to story height have the least value of ductility. As a conservative approach, a ductility factor of 3 for MRS structures is proposed. In addition, in MRSSW structures, for 4, 8 and 12 story structures, as a representative of low-rise, mid-rise and high-rise structures, the ductility factors of 6, 4 and 3 are suggested.