A variable stiffness energy dissipation device for drift control of steel frames

A novel variable stiffness energy dissipation device is conceptualized and numerically studied in this paper. The proposed device is a passive device that consists of an array of helical springs arranged in the form of a series of von Mises trusses anchored between two tubes. Under an external excitation, the tubes move relative to each other and energy is dissipated when the von Mises trusses undergo snap-through and snap-back actions. After presenting the theoretical underpinning of this device, its behavior is programmed using C++ and incorporated into the framework of an open-source software OpenSees. Non-linear time history analyses are then performed on several shear, moment resisting and braced frames to demonstrate the effectiveness of the device in dissipating energy and reducing structural deformations. The results show that the proposed device is capable of reducing both the peak and residual displacements of shear and moment frames, and preventing brace buckling of braced frames under three different levels of earthquake severity.