Vibration analysis of nonlinear conical spring bracing system subjected to seismic load

摘要

In this study, an attempt has been made to assess the impact of proposed nonlinear conical spring bracing (NCSB) system on seismic response subjected to earthquake. The developed system includes of two telescopic conical spring springs that operate in axial compression. Due to shape of spring, the proposed system can performed as a nonlinear stiffness element that provide more lateral stability to structural frame. The action of NCSB does not control the low and moderate vibration due to earthquake but it acts for severe vibration whereas the frame displacement pass the allowable boundary. This inconstant performance avoids excessive effects of conventional bracing system if they attached as retrofitting components to moment resistant steel frame. by other words, due to the aforementioned characteristics of NCSB system, the inherent ductility of steel frame is not scarified and earthquake energy can be dissipate due to frame ductility, but, NCSB system provided more stability of structures and prevent large story drift. In this study, pushover and time history analyses has been conducted to evaluate the seismic performance of introduced device. The results from pushover disclose a considerable enhancement of structural capacity and ductility. Besides, the application on NCSB device changed the location of plastic hinge formation in structural elements. Furthermore, time history results proved the efficiency of NCSB device on reducing the maximum displacement.