عنوان مقاله [English]
Despite the progress in advancing the field of structural control, there is still a vital need to develop new devices to overcome the limitations of the existing approaches to avoiding damages and carrying out attempts to both structural systems and bridge models. Negative Stiffness Device (NSD) is an adaptive system that is purely mechanical and induces negative stiffness behavior in structural systems and bridge models with a pre-compressed spring that pushes the structure away from its equilibrium position. This device produces negative stiffness in a completely in passive manner via a mechanical mechanism without any external power resources for measuring feedback of response of structures with signals of excitation. By engaging the negative stiffness device, composite structure behaves like a yielding structure. The basic advantage of NSD is to distribution manner of the device in several
levels of structures or applying it only in ground level of the structures. This novel device resulted in the applicable weakening and softening concept without any weakening and disconnecting frames, and joints and walls in structures so as to decrease lateral strength and increase displacements, and thus a decrease in base shear and acceleration. Studies in negative stiffness device have been limited to specific experimental structure models with linear and limited nonlinear behavior, which considered as brittle structures. Therefore, this paper focuses on contemplating nonlinear behavior with flexible members with limitation states on damage states that are not considered in former studies. In order to investigate the efficiency of negative stiffness
device on seismic performance of two moment- resisting frames, 5- and 8- story structures with nonlinear behavior on frame elements with the distribution of NSD within the several floors have been considered as the case study configuration in this study. Therefore, incremental dynamic analysis is conducted to identify the effect of NSD system on nonlinear behavior and collapse levels of structural models according to FEMA p\_695 approach. The results presented in this paper demonstrate that by placing an NSD within several floors, the structure above that story undergoes less deformation and, consequently, will be reduced to be suffering from the effects of ground motion.