Development of a nonlinear conical spring bracing system for framed structures subjected to dynamic load

In this study, a nonlinear conical spring bracing (NCSB) system that can be applied as a lateral resistance component in framed structures was developed to mitigate the vibration effects of earthquake and wind. The NCSB device consists of two solid telescopic conical springs attached to steel wire ropes. The application of NCSB in framed structures, particularly moment-resisting steel frame (MRSF), improves the seismic behavior of the frame because of the variable action of the NCSB device. NCSB stiffness is not considerable in the low to medium vibration range compared with structural stiffness. Therefore, the inherent ductility of MRSF is unaffected because of the addition of the NCSB device to the frame. However, with its large displacement value, NCSB stiffness increases and prevents excessive displacement in structures. A mathematical model of the NCSB device that considers the effect of cable stiffness is developed and implemented in program code. Furthermore, the seismic behavior of eight types of NCSB applications in frames subjected to different earthquake accelerations is evaluated in terms of displacement, velocity, and acceleration, as well as compared with bare and brace frames. Results reveal the reduction influences of the NCSB device on framed structures. The best geometric configuration for the NCSB system is also determined by using the proposed numerical analysis.